LCOV - code coverage report
Current view: directory - media/libjpeg - jquant1.c (source / functions) Found Hit Coverage
Test: app.info Lines: 286 0 0.0 %
Date: 2012-06-02 Functions: 17 0 0.0 %

       1                 : /*
       2                 :  * jquant1.c
       3                 :  *
       4                 :  * Copyright (C) 1991-1996, Thomas G. Lane.
       5                 :  * Copyright (C) 2009, D. R. Commander
       6                 :  * This file is part of the Independent JPEG Group's software.
       7                 :  * For conditions of distribution and use, see the accompanying README file.
       8                 :  *
       9                 :  * This file contains 1-pass color quantization (color mapping) routines.
      10                 :  * These routines provide mapping to a fixed color map using equally spaced
      11                 :  * color values.  Optional Floyd-Steinberg or ordered dithering is available.
      12                 :  */
      13                 : 
      14                 : #define JPEG_INTERNALS
      15                 : #include "jinclude.h"
      16                 : #include "jpeglib.h"
      17                 : 
      18                 : #ifdef QUANT_1PASS_SUPPORTED
      19                 : 
      20                 : 
      21                 : /*
      22                 :  * The main purpose of 1-pass quantization is to provide a fast, if not very
      23                 :  * high quality, colormapped output capability.  A 2-pass quantizer usually
      24                 :  * gives better visual quality; however, for quantized grayscale output this
      25                 :  * quantizer is perfectly adequate.  Dithering is highly recommended with this
      26                 :  * quantizer, though you can turn it off if you really want to.
      27                 :  *
      28                 :  * In 1-pass quantization the colormap must be chosen in advance of seeing the
      29                 :  * image.  We use a map consisting of all combinations of Ncolors[i] color
      30                 :  * values for the i'th component.  The Ncolors[] values are chosen so that
      31                 :  * their product, the total number of colors, is no more than that requested.
      32                 :  * (In most cases, the product will be somewhat less.)
      33                 :  *
      34                 :  * Since the colormap is orthogonal, the representative value for each color
      35                 :  * component can be determined without considering the other components;
      36                 :  * then these indexes can be combined into a colormap index by a standard
      37                 :  * N-dimensional-array-subscript calculation.  Most of the arithmetic involved
      38                 :  * can be precalculated and stored in the lookup table colorindex[].
      39                 :  * colorindex[i][j] maps pixel value j in component i to the nearest
      40                 :  * representative value (grid plane) for that component; this index is
      41                 :  * multiplied by the array stride for component i, so that the
      42                 :  * index of the colormap entry closest to a given pixel value is just
      43                 :  *    sum( colorindex[component-number][pixel-component-value] )
      44                 :  * Aside from being fast, this scheme allows for variable spacing between
      45                 :  * representative values with no additional lookup cost.
      46                 :  *
      47                 :  * If gamma correction has been applied in color conversion, it might be wise
      48                 :  * to adjust the color grid spacing so that the representative colors are
      49                 :  * equidistant in linear space.  At this writing, gamma correction is not
      50                 :  * implemented by jdcolor, so nothing is done here.
      51                 :  */
      52                 : 
      53                 : 
      54                 : /* Declarations for ordered dithering.
      55                 :  *
      56                 :  * We use a standard 16x16 ordered dither array.  The basic concept of ordered
      57                 :  * dithering is described in many references, for instance Dale Schumacher's
      58                 :  * chapter II.2 of Graphics Gems II (James Arvo, ed. Academic Press, 1991).
      59                 :  * In place of Schumacher's comparisons against a "threshold" value, we add a
      60                 :  * "dither" value to the input pixel and then round the result to the nearest
      61                 :  * output value.  The dither value is equivalent to (0.5 - threshold) times
      62                 :  * the distance between output values.  For ordered dithering, we assume that
      63                 :  * the output colors are equally spaced; if not, results will probably be
      64                 :  * worse, since the dither may be too much or too little at a given point.
      65                 :  *
      66                 :  * The normal calculation would be to form pixel value + dither, range-limit
      67                 :  * this to 0..MAXJSAMPLE, and then index into the colorindex table as usual.
      68                 :  * We can skip the separate range-limiting step by extending the colorindex
      69                 :  * table in both directions.
      70                 :  */
      71                 : 
      72                 : #define ODITHER_SIZE  16        /* dimension of dither matrix */
      73                 : /* NB: if ODITHER_SIZE is not a power of 2, ODITHER_MASK uses will break */
      74                 : #define ODITHER_CELLS (ODITHER_SIZE*ODITHER_SIZE)       /* # cells in matrix */
      75                 : #define ODITHER_MASK  (ODITHER_SIZE-1) /* mask for wrapping around counters */
      76                 : 
      77                 : typedef int ODITHER_MATRIX[ODITHER_SIZE][ODITHER_SIZE];
      78                 : typedef int (*ODITHER_MATRIX_PTR)[ODITHER_SIZE];
      79                 : 
      80                 : static const UINT8 base_dither_matrix[ODITHER_SIZE][ODITHER_SIZE] = {
      81                 :   /* Bayer's order-4 dither array.  Generated by the code given in
      82                 :    * Stephen Hawley's article "Ordered Dithering" in Graphics Gems I.
      83                 :    * The values in this array must range from 0 to ODITHER_CELLS-1.
      84                 :    */
      85                 :   {   0,192, 48,240, 12,204, 60,252,  3,195, 51,243, 15,207, 63,255 },
      86                 :   { 128, 64,176,112,140, 76,188,124,131, 67,179,115,143, 79,191,127 },
      87                 :   {  32,224, 16,208, 44,236, 28,220, 35,227, 19,211, 47,239, 31,223 },
      88                 :   { 160, 96,144, 80,172,108,156, 92,163, 99,147, 83,175,111,159, 95 },
      89                 :   {   8,200, 56,248,  4,196, 52,244, 11,203, 59,251,  7,199, 55,247 },
      90                 :   { 136, 72,184,120,132, 68,180,116,139, 75,187,123,135, 71,183,119 },
      91                 :   {  40,232, 24,216, 36,228, 20,212, 43,235, 27,219, 39,231, 23,215 },
      92                 :   { 168,104,152, 88,164,100,148, 84,171,107,155, 91,167,103,151, 87 },
      93                 :   {   2,194, 50,242, 14,206, 62,254,  1,193, 49,241, 13,205, 61,253 },
      94                 :   { 130, 66,178,114,142, 78,190,126,129, 65,177,113,141, 77,189,125 },
      95                 :   {  34,226, 18,210, 46,238, 30,222, 33,225, 17,209, 45,237, 29,221 },
      96                 :   { 162, 98,146, 82,174,110,158, 94,161, 97,145, 81,173,109,157, 93 },
      97                 :   {  10,202, 58,250,  6,198, 54,246,  9,201, 57,249,  5,197, 53,245 },
      98                 :   { 138, 74,186,122,134, 70,182,118,137, 73,185,121,133, 69,181,117 },
      99                 :   {  42,234, 26,218, 38,230, 22,214, 41,233, 25,217, 37,229, 21,213 },
     100                 :   { 170,106,154, 90,166,102,150, 86,169,105,153, 89,165,101,149, 85 }
     101                 : };
     102                 : 
     103                 : 
     104                 : /* Declarations for Floyd-Steinberg dithering.
     105                 :  *
     106                 :  * Errors are accumulated into the array fserrors[], at a resolution of
     107                 :  * 1/16th of a pixel count.  The error at a given pixel is propagated
     108                 :  * to its not-yet-processed neighbors using the standard F-S fractions,
     109                 :  *              ...     (here)  7/16
     110                 :  *              3/16    5/16    1/16
     111                 :  * We work left-to-right on even rows, right-to-left on odd rows.
     112                 :  *
     113                 :  * We can get away with a single array (holding one row's worth of errors)
     114                 :  * by using it to store the current row's errors at pixel columns not yet
     115                 :  * processed, but the next row's errors at columns already processed.  We
     116                 :  * need only a few extra variables to hold the errors immediately around the
     117                 :  * current column.  (If we are lucky, those variables are in registers, but
     118                 :  * even if not, they're probably cheaper to access than array elements are.)
     119                 :  *
     120                 :  * The fserrors[] array is indexed [component#][position].
     121                 :  * We provide (#columns + 2) entries per component; the extra entry at each
     122                 :  * end saves us from special-casing the first and last pixels.
     123                 :  *
     124                 :  * Note: on a wide image, we might not have enough room in a PC's near data
     125                 :  * segment to hold the error array; so it is allocated with alloc_large.
     126                 :  */
     127                 : 
     128                 : #if BITS_IN_JSAMPLE == 8
     129                 : typedef INT16 FSERROR;          /* 16 bits should be enough */
     130                 : typedef int LOCFSERROR;         /* use 'int' for calculation temps */
     131                 : #else
     132                 : typedef INT32 FSERROR;          /* may need more than 16 bits */
     133                 : typedef INT32 LOCFSERROR;       /* be sure calculation temps are big enough */
     134                 : #endif
     135                 : 
     136                 : typedef FSERROR FAR *FSERRPTR;  /* pointer to error array (in FAR storage!) */
     137                 : 
     138                 : 
     139                 : /* Private subobject */
     140                 : 
     141                 : #define MAX_Q_COMPS 4           /* max components I can handle */
     142                 : 
     143                 : typedef struct {
     144                 :   struct jpeg_color_quantizer pub; /* public fields */
     145                 : 
     146                 :   /* Initially allocated colormap is saved here */
     147                 :   JSAMPARRAY sv_colormap;       /* The color map as a 2-D pixel array */
     148                 :   int sv_actual;                /* number of entries in use */
     149                 : 
     150                 :   JSAMPARRAY colorindex;        /* Precomputed mapping for speed */
     151                 :   /* colorindex[i][j] = index of color closest to pixel value j in component i,
     152                 :    * premultiplied as described above.  Since colormap indexes must fit into
     153                 :    * JSAMPLEs, the entries of this array will too.
     154                 :    */
     155                 :   boolean is_padded;            /* is the colorindex padded for odither? */
     156                 : 
     157                 :   int Ncolors[MAX_Q_COMPS];     /* # of values alloced to each component */
     158                 : 
     159                 :   /* Variables for ordered dithering */
     160                 :   int row_index;                /* cur row's vertical index in dither matrix */
     161                 :   ODITHER_MATRIX_PTR odither[MAX_Q_COMPS]; /* one dither array per component */
     162                 : 
     163                 :   /* Variables for Floyd-Steinberg dithering */
     164                 :   FSERRPTR fserrors[MAX_Q_COMPS]; /* accumulated errors */
     165                 :   boolean on_odd_row;           /* flag to remember which row we are on */
     166                 : } my_cquantizer;
     167                 : 
     168                 : typedef my_cquantizer * my_cquantize_ptr;
     169                 : 
     170                 : 
     171                 : /*
     172                 :  * Policy-making subroutines for create_colormap and create_colorindex.
     173                 :  * These routines determine the colormap to be used.  The rest of the module
     174                 :  * only assumes that the colormap is orthogonal.
     175                 :  *
     176                 :  *  * select_ncolors decides how to divvy up the available colors
     177                 :  *    among the components.
     178                 :  *  * output_value defines the set of representative values for a component.
     179                 :  *  * largest_input_value defines the mapping from input values to
     180                 :  *    representative values for a component.
     181                 :  * Note that the latter two routines may impose different policies for
     182                 :  * different components, though this is not currently done.
     183                 :  */
     184                 : 
     185                 : 
     186                 : LOCAL(int)
     187               0 : select_ncolors (j_decompress_ptr cinfo, int Ncolors[])
     188                 : /* Determine allocation of desired colors to components, */
     189                 : /* and fill in Ncolors[] array to indicate choice. */
     190                 : /* Return value is total number of colors (product of Ncolors[] values). */
     191                 : {
     192               0 :   int nc = cinfo->out_color_components; /* number of color components */
     193               0 :   int max_colors = cinfo->desired_number_of_colors;
     194                 :   int total_colors, iroot, i, j;
     195                 :   boolean changed;
     196                 :   long temp;
     197               0 :   int RGB_order[3] = { RGB_GREEN, RGB_RED, RGB_BLUE };
     198               0 :   RGB_order[0] = rgb_green[cinfo->out_color_space];
     199               0 :   RGB_order[1] = rgb_red[cinfo->out_color_space];
     200               0 :   RGB_order[2] = rgb_blue[cinfo->out_color_space];
     201                 : 
     202                 :   /* We can allocate at least the nc'th root of max_colors per component. */
     203                 :   /* Compute floor(nc'th root of max_colors). */
     204               0 :   iroot = 1;
     205                 :   do {
     206               0 :     iroot++;
     207               0 :     temp = iroot;               /* set temp = iroot ** nc */
     208               0 :     for (i = 1; i < nc; i++)
     209               0 :       temp *= iroot;
     210               0 :   } while (temp <= (long) max_colors); /* repeat till iroot exceeds root */
     211               0 :   iroot--;                      /* now iroot = floor(root) */
     212                 : 
     213                 :   /* Must have at least 2 color values per component */
     214               0 :   if (iroot < 2)
     215               0 :     ERREXIT1(cinfo, JERR_QUANT_FEW_COLORS, (int) temp);
     216                 : 
     217                 :   /* Initialize to iroot color values for each component */
     218               0 :   total_colors = 1;
     219               0 :   for (i = 0; i < nc; i++) {
     220               0 :     Ncolors[i] = iroot;
     221               0 :     total_colors *= iroot;
     222                 :   }
     223                 :   /* We may be able to increment the count for one or more components without
     224                 :    * exceeding max_colors, though we know not all can be incremented.
     225                 :    * Sometimes, the first component can be incremented more than once!
     226                 :    * (Example: for 16 colors, we start at 2*2*2, go to 3*2*2, then 4*2*2.)
     227                 :    * In RGB colorspace, try to increment G first, then R, then B.
     228                 :    */
     229                 :   do {
     230               0 :     changed = FALSE;
     231               0 :     for (i = 0; i < nc; i++) {
     232               0 :       j = (cinfo->out_color_space == JCS_RGB ? RGB_order[i] : i);
     233                 :       /* calculate new total_colors if Ncolors[j] is incremented */
     234               0 :       temp = total_colors / Ncolors[j];
     235               0 :       temp *= Ncolors[j]+1;     /* done in long arith to avoid oflo */
     236               0 :       if (temp > (long) max_colors)
     237               0 :         break;                  /* won't fit, done with this pass */
     238               0 :       Ncolors[j]++;             /* OK, apply the increment */
     239               0 :       total_colors = (int) temp;
     240               0 :       changed = TRUE;
     241                 :     }
     242               0 :   } while (changed);
     243                 : 
     244               0 :   return total_colors;
     245                 : }
     246                 : 
     247                 : 
     248                 : LOCAL(int)
     249               0 : output_value (j_decompress_ptr cinfo, int ci, int j, int maxj)
     250                 : /* Return j'th output value, where j will range from 0 to maxj */
     251                 : /* The output values must fall in 0..MAXJSAMPLE in increasing order */
     252                 : {
     253                 :   /* We always provide values 0 and MAXJSAMPLE for each component;
     254                 :    * any additional values are equally spaced between these limits.
     255                 :    * (Forcing the upper and lower values to the limits ensures that
     256                 :    * dithering can't produce a color outside the selected gamut.)
     257                 :    */
     258               0 :   return (int) (((INT32) j * MAXJSAMPLE + maxj/2) / maxj);
     259                 : }
     260                 : 
     261                 : 
     262                 : LOCAL(int)
     263               0 : largest_input_value (j_decompress_ptr cinfo, int ci, int j, int maxj)
     264                 : /* Return largest input value that should map to j'th output value */
     265                 : /* Must have largest(j=0) >= 0, and largest(j=maxj) >= MAXJSAMPLE */
     266                 : {
     267                 :   /* Breakpoints are halfway between values returned by output_value */
     268               0 :   return (int) (((INT32) (2*j + 1) * MAXJSAMPLE + maxj) / (2*maxj));
     269                 : }
     270                 : 
     271                 : 
     272                 : /*
     273                 :  * Create the colormap.
     274                 :  */
     275                 : 
     276                 : LOCAL(void)
     277               0 : create_colormap (j_decompress_ptr cinfo)
     278                 : {
     279               0 :   my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
     280                 :   JSAMPARRAY colormap;          /* Created colormap */
     281                 :   int total_colors;             /* Number of distinct output colors */
     282                 :   int i,j,k, nci, blksize, blkdist, ptr, val;
     283                 : 
     284                 :   /* Select number of colors for each component */
     285               0 :   total_colors = select_ncolors(cinfo, cquantize->Ncolors);
     286                 : 
     287                 :   /* Report selected color counts */
     288               0 :   if (cinfo->out_color_components == 3)
     289               0 :     TRACEMS4(cinfo, 1, JTRC_QUANT_3_NCOLORS,
     290                 :              total_colors, cquantize->Ncolors[0],
     291                 :              cquantize->Ncolors[1], cquantize->Ncolors[2]);
     292                 :   else
     293               0 :     TRACEMS1(cinfo, 1, JTRC_QUANT_NCOLORS, total_colors);
     294                 : 
     295                 :   /* Allocate and fill in the colormap. */
     296                 :   /* The colors are ordered in the map in standard row-major order, */
     297                 :   /* i.e. rightmost (highest-indexed) color changes most rapidly. */
     298                 : 
     299               0 :   colormap = (*cinfo->mem->alloc_sarray)
     300               0 :     ((j_common_ptr) cinfo, JPOOL_IMAGE,
     301               0 :      (JDIMENSION) total_colors, (JDIMENSION) cinfo->out_color_components);
     302                 : 
     303                 :   /* blksize is number of adjacent repeated entries for a component */
     304                 :   /* blkdist is distance between groups of identical entries for a component */
     305               0 :   blkdist = total_colors;
     306                 : 
     307               0 :   for (i = 0; i < cinfo->out_color_components; i++) {
     308                 :     /* fill in colormap entries for i'th color component */
     309               0 :     nci = cquantize->Ncolors[i]; /* # of distinct values for this color */
     310               0 :     blksize = blkdist / nci;
     311               0 :     for (j = 0; j < nci; j++) {
     312                 :       /* Compute j'th output value (out of nci) for component */
     313               0 :       val = output_value(cinfo, i, j, nci-1);
     314                 :       /* Fill in all colormap entries that have this value of this component */
     315               0 :       for (ptr = j * blksize; ptr < total_colors; ptr += blkdist) {
     316                 :         /* fill in blksize entries beginning at ptr */
     317               0 :         for (k = 0; k < blksize; k++)
     318               0 :           colormap[i][ptr+k] = (JSAMPLE) val;
     319                 :       }
     320                 :     }
     321               0 :     blkdist = blksize;          /* blksize of this color is blkdist of next */
     322                 :   }
     323                 : 
     324                 :   /* Save the colormap in private storage,
     325                 :    * where it will survive color quantization mode changes.
     326                 :    */
     327               0 :   cquantize->sv_colormap = colormap;
     328               0 :   cquantize->sv_actual = total_colors;
     329               0 : }
     330                 : 
     331                 : 
     332                 : /*
     333                 :  * Create the color index table.
     334                 :  */
     335                 : 
     336                 : LOCAL(void)
     337               0 : create_colorindex (j_decompress_ptr cinfo)
     338                 : {
     339               0 :   my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
     340                 :   JSAMPROW indexptr;
     341                 :   int i,j,k, nci, blksize, val, pad;
     342                 : 
     343                 :   /* For ordered dither, we pad the color index tables by MAXJSAMPLE in
     344                 :    * each direction (input index values can be -MAXJSAMPLE .. 2*MAXJSAMPLE).
     345                 :    * This is not necessary in the other dithering modes.  However, we
     346                 :    * flag whether it was done in case user changes dithering mode.
     347                 :    */
     348               0 :   if (cinfo->dither_mode == JDITHER_ORDERED) {
     349               0 :     pad = MAXJSAMPLE*2;
     350               0 :     cquantize->is_padded = TRUE;
     351                 :   } else {
     352               0 :     pad = 0;
     353               0 :     cquantize->is_padded = FALSE;
     354                 :   }
     355                 : 
     356               0 :   cquantize->colorindex = (*cinfo->mem->alloc_sarray)
     357               0 :     ((j_common_ptr) cinfo, JPOOL_IMAGE,
     358               0 :      (JDIMENSION) (MAXJSAMPLE+1 + pad),
     359               0 :      (JDIMENSION) cinfo->out_color_components);
     360                 : 
     361                 :   /* blksize is number of adjacent repeated entries for a component */
     362               0 :   blksize = cquantize->sv_actual;
     363                 : 
     364               0 :   for (i = 0; i < cinfo->out_color_components; i++) {
     365                 :     /* fill in colorindex entries for i'th color component */
     366               0 :     nci = cquantize->Ncolors[i]; /* # of distinct values for this color */
     367               0 :     blksize = blksize / nci;
     368                 : 
     369                 :     /* adjust colorindex pointers to provide padding at negative indexes. */
     370               0 :     if (pad)
     371               0 :       cquantize->colorindex[i] += MAXJSAMPLE;
     372                 : 
     373                 :     /* in loop, val = index of current output value, */
     374                 :     /* and k = largest j that maps to current val */
     375               0 :     indexptr = cquantize->colorindex[i];
     376               0 :     val = 0;
     377               0 :     k = largest_input_value(cinfo, i, 0, nci-1);
     378               0 :     for (j = 0; j <= MAXJSAMPLE; j++) {
     379               0 :       while (j > k)          /* advance val if past boundary */
     380               0 :         k = largest_input_value(cinfo, i, ++val, nci-1);
     381                 :       /* premultiply so that no multiplication needed in main processing */
     382               0 :       indexptr[j] = (JSAMPLE) (val * blksize);
     383                 :     }
     384                 :     /* Pad at both ends if necessary */
     385               0 :     if (pad)
     386               0 :       for (j = 1; j <= MAXJSAMPLE; j++) {
     387               0 :         indexptr[-j] = indexptr[0];
     388               0 :         indexptr[MAXJSAMPLE+j] = indexptr[MAXJSAMPLE];
     389                 :       }
     390                 :   }
     391               0 : }
     392                 : 
     393                 : 
     394                 : /*
     395                 :  * Create an ordered-dither array for a component having ncolors
     396                 :  * distinct output values.
     397                 :  */
     398                 : 
     399                 : LOCAL(ODITHER_MATRIX_PTR)
     400               0 : make_odither_array (j_decompress_ptr cinfo, int ncolors)
     401                 : {
     402                 :   ODITHER_MATRIX_PTR odither;
     403                 :   int j,k;
     404                 :   INT32 num,den;
     405                 : 
     406               0 :   odither = (ODITHER_MATRIX_PTR)
     407               0 :     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
     408                 :                                 SIZEOF(ODITHER_MATRIX));
     409                 :   /* The inter-value distance for this color is MAXJSAMPLE/(ncolors-1).
     410                 :    * Hence the dither value for the matrix cell with fill order f
     411                 :    * (f=0..N-1) should be (N-1-2*f)/(2*N) * MAXJSAMPLE/(ncolors-1).
     412                 :    * On 16-bit-int machine, be careful to avoid overflow.
     413                 :    */
     414               0 :   den = 2 * ODITHER_CELLS * ((INT32) (ncolors - 1));
     415               0 :   for (j = 0; j < ODITHER_SIZE; j++) {
     416               0 :     for (k = 0; k < ODITHER_SIZE; k++) {
     417               0 :       num = ((INT32) (ODITHER_CELLS-1 - 2*((int)base_dither_matrix[j][k])))
     418               0 :             * MAXJSAMPLE;
     419                 :       /* Ensure round towards zero despite C's lack of consistency
     420                 :        * about rounding negative values in integer division...
     421                 :        */
     422               0 :       odither[j][k] = (int) (num<0 ? -((-num)/den) : num/den);
     423                 :     }
     424                 :   }
     425               0 :   return odither;
     426                 : }
     427                 : 
     428                 : 
     429                 : /*
     430                 :  * Create the ordered-dither tables.
     431                 :  * Components having the same number of representative colors may 
     432                 :  * share a dither table.
     433                 :  */
     434                 : 
     435                 : LOCAL(void)
     436               0 : create_odither_tables (j_decompress_ptr cinfo)
     437                 : {
     438               0 :   my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
     439                 :   ODITHER_MATRIX_PTR odither;
     440                 :   int i, j, nci;
     441                 : 
     442               0 :   for (i = 0; i < cinfo->out_color_components; i++) {
     443               0 :     nci = cquantize->Ncolors[i]; /* # of distinct values for this color */
     444               0 :     odither = NULL;             /* search for matching prior component */
     445               0 :     for (j = 0; j < i; j++) {
     446               0 :       if (nci == cquantize->Ncolors[j]) {
     447               0 :         odither = cquantize->odither[j];
     448               0 :         break;
     449                 :       }
     450                 :     }
     451               0 :     if (odither == NULL)        /* need a new table? */
     452               0 :       odither = make_odither_array(cinfo, nci);
     453               0 :     cquantize->odither[i] = odither;
     454                 :   }
     455               0 : }
     456                 : 
     457                 : 
     458                 : /*
     459                 :  * Map some rows of pixels to the output colormapped representation.
     460                 :  */
     461                 : 
     462                 : METHODDEF(void)
     463               0 : color_quantize (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
     464                 :                 JSAMPARRAY output_buf, int num_rows)
     465                 : /* General case, no dithering */
     466                 : {
     467               0 :   my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
     468               0 :   JSAMPARRAY colorindex = cquantize->colorindex;
     469                 :   register int pixcode, ci;
     470                 :   register JSAMPROW ptrin, ptrout;
     471                 :   int row;
     472                 :   JDIMENSION col;
     473               0 :   JDIMENSION width = cinfo->output_width;
     474               0 :   register int nc = cinfo->out_color_components;
     475                 : 
     476               0 :   for (row = 0; row < num_rows; row++) {
     477               0 :     ptrin = input_buf[row];
     478               0 :     ptrout = output_buf[row];
     479               0 :     for (col = width; col > 0; col--) {
     480               0 :       pixcode = 0;
     481               0 :       for (ci = 0; ci < nc; ci++) {
     482               0 :         pixcode += GETJSAMPLE(colorindex[ci][GETJSAMPLE(*ptrin++)]);
     483                 :       }
     484               0 :       *ptrout++ = (JSAMPLE) pixcode;
     485                 :     }
     486                 :   }
     487               0 : }
     488                 : 
     489                 : 
     490                 : METHODDEF(void)
     491               0 : color_quantize3 (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
     492                 :                  JSAMPARRAY output_buf, int num_rows)
     493                 : /* Fast path for out_color_components==3, no dithering */
     494                 : {
     495               0 :   my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
     496                 :   register int pixcode;
     497                 :   register JSAMPROW ptrin, ptrout;
     498               0 :   JSAMPROW colorindex0 = cquantize->colorindex[0];
     499               0 :   JSAMPROW colorindex1 = cquantize->colorindex[1];
     500               0 :   JSAMPROW colorindex2 = cquantize->colorindex[2];
     501                 :   int row;
     502                 :   JDIMENSION col;
     503               0 :   JDIMENSION width = cinfo->output_width;
     504                 : 
     505               0 :   for (row = 0; row < num_rows; row++) {
     506               0 :     ptrin = input_buf[row];
     507               0 :     ptrout = output_buf[row];
     508               0 :     for (col = width; col > 0; col--) {
     509               0 :       pixcode  = GETJSAMPLE(colorindex0[GETJSAMPLE(*ptrin++)]);
     510               0 :       pixcode += GETJSAMPLE(colorindex1[GETJSAMPLE(*ptrin++)]);
     511               0 :       pixcode += GETJSAMPLE(colorindex2[GETJSAMPLE(*ptrin++)]);
     512               0 :       *ptrout++ = (JSAMPLE) pixcode;
     513                 :     }
     514                 :   }
     515               0 : }
     516                 : 
     517                 : 
     518                 : METHODDEF(void)
     519               0 : quantize_ord_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
     520                 :                      JSAMPARRAY output_buf, int num_rows)
     521                 : /* General case, with ordered dithering */
     522                 : {
     523               0 :   my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
     524                 :   register JSAMPROW input_ptr;
     525                 :   register JSAMPROW output_ptr;
     526                 :   JSAMPROW colorindex_ci;
     527                 :   int * dither;                 /* points to active row of dither matrix */
     528                 :   int row_index, col_index;     /* current indexes into dither matrix */
     529               0 :   int nc = cinfo->out_color_components;
     530                 :   int ci;
     531                 :   int row;
     532                 :   JDIMENSION col;
     533               0 :   JDIMENSION width = cinfo->output_width;
     534                 : 
     535               0 :   for (row = 0; row < num_rows; row++) {
     536                 :     /* Initialize output values to 0 so can process components separately */
     537               0 :     jzero_far((void FAR *) output_buf[row],
     538                 :               (size_t) (width * SIZEOF(JSAMPLE)));
     539               0 :     row_index = cquantize->row_index;
     540               0 :     for (ci = 0; ci < nc; ci++) {
     541               0 :       input_ptr = input_buf[row] + ci;
     542               0 :       output_ptr = output_buf[row];
     543               0 :       colorindex_ci = cquantize->colorindex[ci];
     544               0 :       dither = cquantize->odither[ci][row_index];
     545               0 :       col_index = 0;
     546                 : 
     547               0 :       for (col = width; col > 0; col--) {
     548                 :         /* Form pixel value + dither, range-limit to 0..MAXJSAMPLE,
     549                 :          * select output value, accumulate into output code for this pixel.
     550                 :          * Range-limiting need not be done explicitly, as we have extended
     551                 :          * the colorindex table to produce the right answers for out-of-range
     552                 :          * inputs.  The maximum dither is +- MAXJSAMPLE; this sets the
     553                 :          * required amount of padding.
     554                 :          */
     555               0 :         *output_ptr += colorindex_ci[GETJSAMPLE(*input_ptr)+dither[col_index]];
     556               0 :         input_ptr += nc;
     557               0 :         output_ptr++;
     558               0 :         col_index = (col_index + 1) & ODITHER_MASK;
     559                 :       }
     560                 :     }
     561                 :     /* Advance row index for next row */
     562               0 :     row_index = (row_index + 1) & ODITHER_MASK;
     563               0 :     cquantize->row_index = row_index;
     564                 :   }
     565               0 : }
     566                 : 
     567                 : 
     568                 : METHODDEF(void)
     569               0 : quantize3_ord_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
     570                 :                       JSAMPARRAY output_buf, int num_rows)
     571                 : /* Fast path for out_color_components==3, with ordered dithering */
     572                 : {
     573               0 :   my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
     574                 :   register int pixcode;
     575                 :   register JSAMPROW input_ptr;
     576                 :   register JSAMPROW output_ptr;
     577               0 :   JSAMPROW colorindex0 = cquantize->colorindex[0];
     578               0 :   JSAMPROW colorindex1 = cquantize->colorindex[1];
     579               0 :   JSAMPROW colorindex2 = cquantize->colorindex[2];
     580                 :   int * dither0;                /* points to active row of dither matrix */
     581                 :   int * dither1;
     582                 :   int * dither2;
     583                 :   int row_index, col_index;     /* current indexes into dither matrix */
     584                 :   int row;
     585                 :   JDIMENSION col;
     586               0 :   JDIMENSION width = cinfo->output_width;
     587                 : 
     588               0 :   for (row = 0; row < num_rows; row++) {
     589               0 :     row_index = cquantize->row_index;
     590               0 :     input_ptr = input_buf[row];
     591               0 :     output_ptr = output_buf[row];
     592               0 :     dither0 = cquantize->odither[0][row_index];
     593               0 :     dither1 = cquantize->odither[1][row_index];
     594               0 :     dither2 = cquantize->odither[2][row_index];
     595               0 :     col_index = 0;
     596                 : 
     597               0 :     for (col = width; col > 0; col--) {
     598               0 :       pixcode  = GETJSAMPLE(colorindex0[GETJSAMPLE(*input_ptr++) +
     599                 :                                         dither0[col_index]]);
     600               0 :       pixcode += GETJSAMPLE(colorindex1[GETJSAMPLE(*input_ptr++) +
     601                 :                                         dither1[col_index]]);
     602               0 :       pixcode += GETJSAMPLE(colorindex2[GETJSAMPLE(*input_ptr++) +
     603                 :                                         dither2[col_index]]);
     604               0 :       *output_ptr++ = (JSAMPLE) pixcode;
     605               0 :       col_index = (col_index + 1) & ODITHER_MASK;
     606                 :     }
     607               0 :     row_index = (row_index + 1) & ODITHER_MASK;
     608               0 :     cquantize->row_index = row_index;
     609                 :   }
     610               0 : }
     611                 : 
     612                 : 
     613                 : METHODDEF(void)
     614               0 : quantize_fs_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
     615                 :                     JSAMPARRAY output_buf, int num_rows)
     616                 : /* General case, with Floyd-Steinberg dithering */
     617                 : {
     618               0 :   my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
     619                 :   register LOCFSERROR cur;      /* current error or pixel value */
     620                 :   LOCFSERROR belowerr;          /* error for pixel below cur */
     621                 :   LOCFSERROR bpreverr;          /* error for below/prev col */
     622                 :   LOCFSERROR bnexterr;          /* error for below/next col */
     623                 :   LOCFSERROR delta;
     624                 :   register FSERRPTR errorptr;   /* => fserrors[] at column before current */
     625                 :   register JSAMPROW input_ptr;
     626                 :   register JSAMPROW output_ptr;
     627                 :   JSAMPROW colorindex_ci;
     628                 :   JSAMPROW colormap_ci;
     629                 :   int pixcode;
     630               0 :   int nc = cinfo->out_color_components;
     631                 :   int dir;                      /* 1 for left-to-right, -1 for right-to-left */
     632                 :   int dirnc;                    /* dir * nc */
     633                 :   int ci;
     634                 :   int row;
     635                 :   JDIMENSION col;
     636               0 :   JDIMENSION width = cinfo->output_width;
     637               0 :   JSAMPLE *range_limit = cinfo->sample_range_limit;
     638                 :   SHIFT_TEMPS
     639                 : 
     640               0 :   for (row = 0; row < num_rows; row++) {
     641                 :     /* Initialize output values to 0 so can process components separately */
     642               0 :     jzero_far((void FAR *) output_buf[row],
     643                 :               (size_t) (width * SIZEOF(JSAMPLE)));
     644               0 :     for (ci = 0; ci < nc; ci++) {
     645               0 :       input_ptr = input_buf[row] + ci;
     646               0 :       output_ptr = output_buf[row];
     647               0 :       if (cquantize->on_odd_row) {
     648                 :         /* work right to left in this row */
     649               0 :         input_ptr += (width-1) * nc; /* so point to rightmost pixel */
     650               0 :         output_ptr += width-1;
     651               0 :         dir = -1;
     652               0 :         dirnc = -nc;
     653               0 :         errorptr = cquantize->fserrors[ci] + (width+1); /* => entry after last column */
     654                 :       } else {
     655                 :         /* work left to right in this row */
     656               0 :         dir = 1;
     657               0 :         dirnc = nc;
     658               0 :         errorptr = cquantize->fserrors[ci]; /* => entry before first column */
     659                 :       }
     660               0 :       colorindex_ci = cquantize->colorindex[ci];
     661               0 :       colormap_ci = cquantize->sv_colormap[ci];
     662                 :       /* Preset error values: no error propagated to first pixel from left */
     663               0 :       cur = 0;
     664                 :       /* and no error propagated to row below yet */
     665               0 :       belowerr = bpreverr = 0;
     666                 : 
     667               0 :       for (col = width; col > 0; col--) {
     668                 :         /* cur holds the error propagated from the previous pixel on the
     669                 :          * current line.  Add the error propagated from the previous line
     670                 :          * to form the complete error correction term for this pixel, and
     671                 :          * round the error term (which is expressed * 16) to an integer.
     672                 :          * RIGHT_SHIFT rounds towards minus infinity, so adding 8 is correct
     673                 :          * for either sign of the error value.
     674                 :          * Note: errorptr points to *previous* column's array entry.
     675                 :          */
     676               0 :         cur = RIGHT_SHIFT(cur + errorptr[dir] + 8, 4);
     677                 :         /* Form pixel value + error, and range-limit to 0..MAXJSAMPLE.
     678                 :          * The maximum error is +- MAXJSAMPLE; this sets the required size
     679                 :          * of the range_limit array.
     680                 :          */
     681               0 :         cur += GETJSAMPLE(*input_ptr);
     682               0 :         cur = GETJSAMPLE(range_limit[cur]);
     683                 :         /* Select output value, accumulate into output code for this pixel */
     684               0 :         pixcode = GETJSAMPLE(colorindex_ci[cur]);
     685               0 :         *output_ptr += (JSAMPLE) pixcode;
     686                 :         /* Compute actual representation error at this pixel */
     687                 :         /* Note: we can do this even though we don't have the final */
     688                 :         /* pixel code, because the colormap is orthogonal. */
     689               0 :         cur -= GETJSAMPLE(colormap_ci[pixcode]);
     690                 :         /* Compute error fractions to be propagated to adjacent pixels.
     691                 :          * Add these into the running sums, and simultaneously shift the
     692                 :          * next-line error sums left by 1 column.
     693                 :          */
     694               0 :         bnexterr = cur;
     695               0 :         delta = cur * 2;
     696               0 :         cur += delta;           /* form error * 3 */
     697               0 :         errorptr[0] = (FSERROR) (bpreverr + cur);
     698               0 :         cur += delta;           /* form error * 5 */
     699               0 :         bpreverr = belowerr + cur;
     700               0 :         belowerr = bnexterr;
     701               0 :         cur += delta;           /* form error * 7 */
     702                 :         /* At this point cur contains the 7/16 error value to be propagated
     703                 :          * to the next pixel on the current line, and all the errors for the
     704                 :          * next line have been shifted over. We are therefore ready to move on.
     705                 :          */
     706               0 :         input_ptr += dirnc;     /* advance input ptr to next column */
     707               0 :         output_ptr += dir;      /* advance output ptr to next column */
     708               0 :         errorptr += dir;        /* advance errorptr to current column */
     709                 :       }
     710                 :       /* Post-loop cleanup: we must unload the final error value into the
     711                 :        * final fserrors[] entry.  Note we need not unload belowerr because
     712                 :        * it is for the dummy column before or after the actual array.
     713                 :        */
     714               0 :       errorptr[0] = (FSERROR) bpreverr; /* unload prev err into array */
     715                 :     }
     716               0 :     cquantize->on_odd_row = (cquantize->on_odd_row ? FALSE : TRUE);
     717                 :   }
     718               0 : }
     719                 : 
     720                 : 
     721                 : /*
     722                 :  * Allocate workspace for Floyd-Steinberg errors.
     723                 :  */
     724                 : 
     725                 : LOCAL(void)
     726               0 : alloc_fs_workspace (j_decompress_ptr cinfo)
     727                 : {
     728               0 :   my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
     729                 :   size_t arraysize;
     730                 :   int i;
     731                 : 
     732               0 :   arraysize = (size_t) ((cinfo->output_width + 2) * SIZEOF(FSERROR));
     733               0 :   for (i = 0; i < cinfo->out_color_components; i++) {
     734               0 :     cquantize->fserrors[i] = (FSERRPTR)
     735               0 :       (*cinfo->mem->alloc_large)((j_common_ptr) cinfo, JPOOL_IMAGE, arraysize);
     736                 :   }
     737               0 : }
     738                 : 
     739                 : 
     740                 : /*
     741                 :  * Initialize for one-pass color quantization.
     742                 :  */
     743                 : 
     744                 : METHODDEF(void)
     745               0 : start_pass_1_quant (j_decompress_ptr cinfo, boolean is_pre_scan)
     746                 : {
     747               0 :   my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
     748                 :   size_t arraysize;
     749                 :   int i;
     750                 : 
     751                 :   /* Install my colormap. */
     752               0 :   cinfo->colormap = cquantize->sv_colormap;
     753               0 :   cinfo->actual_number_of_colors = cquantize->sv_actual;
     754                 : 
     755                 :   /* Initialize for desired dithering mode. */
     756               0 :   switch (cinfo->dither_mode) {
     757                 :   case JDITHER_NONE:
     758               0 :     if (cinfo->out_color_components == 3)
     759               0 :       cquantize->pub.color_quantize = color_quantize3;
     760                 :     else
     761               0 :       cquantize->pub.color_quantize = color_quantize;
     762               0 :     break;
     763                 :   case JDITHER_ORDERED:
     764               0 :     if (cinfo->out_color_components == 3)
     765               0 :       cquantize->pub.color_quantize = quantize3_ord_dither;
     766                 :     else
     767               0 :       cquantize->pub.color_quantize = quantize_ord_dither;
     768               0 :     cquantize->row_index = 0;        /* initialize state for ordered dither */
     769                 :     /* If user changed to ordered dither from another mode,
     770                 :      * we must recreate the color index table with padding.
     771                 :      * This will cost extra space, but probably isn't very likely.
     772                 :      */
     773               0 :     if (! cquantize->is_padded)
     774               0 :       create_colorindex(cinfo);
     775                 :     /* Create ordered-dither tables if we didn't already. */
     776               0 :     if (cquantize->odither[0] == NULL)
     777               0 :       create_odither_tables(cinfo);
     778               0 :     break;
     779                 :   case JDITHER_FS:
     780               0 :     cquantize->pub.color_quantize = quantize_fs_dither;
     781               0 :     cquantize->on_odd_row = FALSE; /* initialize state for F-S dither */
     782                 :     /* Allocate Floyd-Steinberg workspace if didn't already. */
     783               0 :     if (cquantize->fserrors[0] == NULL)
     784               0 :       alloc_fs_workspace(cinfo);
     785                 :     /* Initialize the propagated errors to zero. */
     786               0 :     arraysize = (size_t) ((cinfo->output_width + 2) * SIZEOF(FSERROR));
     787               0 :     for (i = 0; i < cinfo->out_color_components; i++)
     788               0 :       jzero_far((void FAR *) cquantize->fserrors[i], arraysize);
     789               0 :     break;
     790                 :   default:
     791               0 :     ERREXIT(cinfo, JERR_NOT_COMPILED);
     792               0 :     break;
     793                 :   }
     794               0 : }
     795                 : 
     796                 : 
     797                 : /*
     798                 :  * Finish up at the end of the pass.
     799                 :  */
     800                 : 
     801                 : METHODDEF(void)
     802               0 : finish_pass_1_quant (j_decompress_ptr cinfo)
     803                 : {
     804                 :   /* no work in 1-pass case */
     805               0 : }
     806                 : 
     807                 : 
     808                 : /*
     809                 :  * Switch to a new external colormap between output passes.
     810                 :  * Shouldn't get to this module!
     811                 :  */
     812                 : 
     813                 : METHODDEF(void)
     814               0 : new_color_map_1_quant (j_decompress_ptr cinfo)
     815                 : {
     816               0 :   ERREXIT(cinfo, JERR_MODE_CHANGE);
     817               0 : }
     818                 : 
     819                 : 
     820                 : /*
     821                 :  * Module initialization routine for 1-pass color quantization.
     822                 :  */
     823                 : 
     824                 : GLOBAL(void)
     825               0 : jinit_1pass_quantizer (j_decompress_ptr cinfo)
     826                 : {
     827                 :   my_cquantize_ptr cquantize;
     828                 : 
     829               0 :   cquantize = (my_cquantize_ptr)
     830               0 :     (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
     831                 :                                 SIZEOF(my_cquantizer));
     832               0 :   cinfo->cquantize = (struct jpeg_color_quantizer *) cquantize;
     833               0 :   cquantize->pub.start_pass = start_pass_1_quant;
     834               0 :   cquantize->pub.finish_pass = finish_pass_1_quant;
     835               0 :   cquantize->pub.new_color_map = new_color_map_1_quant;
     836               0 :   cquantize->fserrors[0] = NULL; /* Flag FS workspace not allocated */
     837               0 :   cquantize->odither[0] = NULL;      /* Also flag odither arrays not allocated */
     838                 : 
     839                 :   /* Make sure my internal arrays won't overflow */
     840               0 :   if (cinfo->out_color_components > MAX_Q_COMPS)
     841               0 :     ERREXIT1(cinfo, JERR_QUANT_COMPONENTS, MAX_Q_COMPS);
     842                 :   /* Make sure colormap indexes can be represented by JSAMPLEs */
     843               0 :   if (cinfo->desired_number_of_colors > (MAXJSAMPLE+1))
     844               0 :     ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, MAXJSAMPLE+1);
     845                 : 
     846                 :   /* Create the colormap and color index table. */
     847               0 :   create_colormap(cinfo);
     848               0 :   create_colorindex(cinfo);
     849                 : 
     850                 :   /* Allocate Floyd-Steinberg workspace now if requested.
     851                 :    * We do this now since it is FAR storage and may affect the memory
     852                 :    * manager's space calculations.  If the user changes to FS dither
     853                 :    * mode in a later pass, we will allocate the space then, and will
     854                 :    * possibly overrun the max_memory_to_use setting.
     855                 :    */
     856               0 :   if (cinfo->dither_mode == JDITHER_FS)
     857               0 :     alloc_fs_workspace(cinfo);
     858               0 : }
     859                 : 
     860                 : #endif /* QUANT_1PASS_SUPPORTED */

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