+++ /dev/null
-/*
- * jquant1.c
- *
- * Copyright (C) 1991-1996, Thomas G. Lane.
- * Modified 2011 by Guido Vollbeding.
- * This file is part of the Independent JPEG Group's software.
- * For conditions of distribution and use, see the accompanying README file.
- *
- * This file contains 1-pass color quantization (color mapping) routines.
- * These routines provide mapping to a fixed color map using equally spaced
- * color values. Optional Floyd-Steinberg or ordered dithering is available.
- */
-
-#define JPEG_INTERNALS
-#include "jinclude.h"
-#include "jpeglib.h"
-
-#ifdef QUANT_1PASS_SUPPORTED
-
-
-/*
- * The main purpose of 1-pass quantization is to provide a fast, if not very
- * high quality, colormapped output capability. A 2-pass quantizer usually
- * gives better visual quality; however, for quantized grayscale output this
- * quantizer is perfectly adequate. Dithering is highly recommended with this
- * quantizer, though you can turn it off if you really want to.
- *
- * In 1-pass quantization the colormap must be chosen in advance of seeing the
- * image. We use a map consisting of all combinations of Ncolors[i] color
- * values for the i'th component. The Ncolors[] values are chosen so that
- * their product, the total number of colors, is no more than that requested.
- * (In most cases, the product will be somewhat less.)
- *
- * Since the colormap is orthogonal, the representative value for each color
- * component can be determined without considering the other components;
- * then these indexes can be combined into a colormap index by a standard
- * N-dimensional-array-subscript calculation. Most of the arithmetic involved
- * can be precalculated and stored in the lookup table colorindex[].
- * colorindex[i][j] maps pixel value j in component i to the nearest
- * representative value (grid plane) for that component; this index is
- * multiplied by the array stride for component i, so that the
- * index of the colormap entry closest to a given pixel value is just
- * sum( colorindex[component-number][pixel-component-value] )
- * Aside from being fast, this scheme allows for variable spacing between
- * representative values with no additional lookup cost.
- *
- * If gamma correction has been applied in color conversion, it might be wise
- * to adjust the color grid spacing so that the representative colors are
- * equidistant in linear space. At this writing, gamma correction is not
- * implemented by jdcolor, so nothing is done here.
- */
-
-
-/* Declarations for ordered dithering.
- *
- * We use a standard 16x16 ordered dither array. The basic concept of ordered
- * dithering is described in many references, for instance Dale Schumacher's
- * chapter II.2 of Graphics Gems II (James Arvo, ed. Academic Press, 1991).
- * In place of Schumacher's comparisons against a "threshold" value, we add a
- * "dither" value to the input pixel and then round the result to the nearest
- * output value. The dither value is equivalent to (0.5 - threshold) times
- * the distance between output values. For ordered dithering, we assume that
- * the output colors are equally spaced; if not, results will probably be
- * worse, since the dither may be too much or too little at a given point.
- *
- * The normal calculation would be to form pixel value + dither, range-limit
- * this to 0..MAXJSAMPLE, and then index into the colorindex table as usual.
- * We can skip the separate range-limiting step by extending the colorindex
- * table in both directions.
- */
-
-#define ODITHER_SIZE 16 /* dimension of dither matrix */
-/* NB: if ODITHER_SIZE is not a power of 2, ODITHER_MASK uses will break */
-#define ODITHER_CELLS (ODITHER_SIZE*ODITHER_SIZE) /* # cells in matrix */
-#define ODITHER_MASK (ODITHER_SIZE-1) /* mask for wrapping around counters */
-
-typedef int ODITHER_MATRIX[ODITHER_SIZE][ODITHER_SIZE];
-typedef int (*ODITHER_MATRIX_PTR)[ODITHER_SIZE];
-
-static const UINT8 base_dither_matrix[ODITHER_SIZE][ODITHER_SIZE] = {
- /* Bayer's order-4 dither array. Generated by the code given in
- * Stephen Hawley's article "Ordered Dithering" in Graphics Gems I.
- * The values in this array must range from 0 to ODITHER_CELLS-1.
- */
- { 0,192, 48,240, 12,204, 60,252, 3,195, 51,243, 15,207, 63,255 },
- { 128, 64,176,112,140, 76,188,124,131, 67,179,115,143, 79,191,127 },
- { 32,224, 16,208, 44,236, 28,220, 35,227, 19,211, 47,239, 31,223 },
- { 160, 96,144, 80,172,108,156, 92,163, 99,147, 83,175,111,159, 95 },
- { 8,200, 56,248, 4,196, 52,244, 11,203, 59,251, 7,199, 55,247 },
- { 136, 72,184,120,132, 68,180,116,139, 75,187,123,135, 71,183,119 },
- { 40,232, 24,216, 36,228, 20,212, 43,235, 27,219, 39,231, 23,215 },
- { 168,104,152, 88,164,100,148, 84,171,107,155, 91,167,103,151, 87 },
- { 2,194, 50,242, 14,206, 62,254, 1,193, 49,241, 13,205, 61,253 },
- { 130, 66,178,114,142, 78,190,126,129, 65,177,113,141, 77,189,125 },
- { 34,226, 18,210, 46,238, 30,222, 33,225, 17,209, 45,237, 29,221 },
- { 162, 98,146, 82,174,110,158, 94,161, 97,145, 81,173,109,157, 93 },
- { 10,202, 58,250, 6,198, 54,246, 9,201, 57,249, 5,197, 53,245 },
- { 138, 74,186,122,134, 70,182,118,137, 73,185,121,133, 69,181,117 },
- { 42,234, 26,218, 38,230, 22,214, 41,233, 25,217, 37,229, 21,213 },
- { 170,106,154, 90,166,102,150, 86,169,105,153, 89,165,101,149, 85 }
-};
-
-
-/* Declarations for Floyd-Steinberg dithering.
- *
- * Errors are accumulated into the array fserrors[], at a resolution of
- * 1/16th of a pixel count. The error at a given pixel is propagated
- * to its not-yet-processed neighbors using the standard F-S fractions,
- * ... (here) 7/16
- * 3/16 5/16 1/16
- * We work left-to-right on even rows, right-to-left on odd rows.
- *
- * We can get away with a single array (holding one row's worth of errors)
- * by using it to store the current row's errors at pixel columns not yet
- * processed, but the next row's errors at columns already processed. We
- * need only a few extra variables to hold the errors immediately around the
- * current column. (If we are lucky, those variables are in registers, but
- * even if not, they're probably cheaper to access than array elements are.)
- *
- * The fserrors[] array is indexed [component#][position].
- * We provide (#columns + 2) entries per component; the extra entry at each
- * end saves us from special-casing the first and last pixels.
- *
- * Note: on a wide image, we might not have enough room in a PC's near data
- * segment to hold the error array; so it is allocated with alloc_large.
- */
-
-#if BITS_IN_JSAMPLE == 8
-typedef INT16 FSERROR; /* 16 bits should be enough */
-typedef int LOCFSERROR; /* use 'int' for calculation temps */
-#else
-typedef INT32 FSERROR; /* may need more than 16 bits */
-typedef INT32 LOCFSERROR; /* be sure calculation temps are big enough */
-#endif
-
-typedef FSERROR FAR *FSERRPTR; /* pointer to error array (in FAR storage!) */
-
-
-/* Private subobject */
-
-#define MAX_Q_COMPS 4 /* max components I can handle */
-
-typedef struct {
- struct jpeg_color_quantizer pub; /* public fields */
-
- /* Initially allocated colormap is saved here */
- JSAMPARRAY sv_colormap; /* The color map as a 2-D pixel array */
- int sv_actual; /* number of entries in use */
-
- JSAMPARRAY colorindex; /* Precomputed mapping for speed */
- /* colorindex[i][j] = index of color closest to pixel value j in component i,
- * premultiplied as described above. Since colormap indexes must fit into
- * JSAMPLEs, the entries of this array will too.
- */
- boolean is_padded; /* is the colorindex padded for odither? */
-
- int Ncolors[MAX_Q_COMPS]; /* # of values alloced to each component */
-
- /* Variables for ordered dithering */
- int row_index; /* cur row's vertical index in dither matrix */
- ODITHER_MATRIX_PTR odither[MAX_Q_COMPS]; /* one dither array per component */
-
- /* Variables for Floyd-Steinberg dithering */
- FSERRPTR fserrors[MAX_Q_COMPS]; /* accumulated errors */
- boolean on_odd_row; /* flag to remember which row we are on */
-} my_cquantizer;
-
-typedef my_cquantizer * my_cquantize_ptr;
-
-
-/*
- * Policy-making subroutines for create_colormap and create_colorindex.
- * These routines determine the colormap to be used. The rest of the module
- * only assumes that the colormap is orthogonal.
- *
- * * select_ncolors decides how to divvy up the available colors
- * among the components.
- * * output_value defines the set of representative values for a component.
- * * largest_input_value defines the mapping from input values to
- * representative values for a component.
- * Note that the latter two routines may impose different policies for
- * different components, though this is not currently done.
- */
-
-
-LOCAL(int)
-select_ncolors (j_decompress_ptr cinfo, int Ncolors[])
-/* Determine allocation of desired colors to components, */
-/* and fill in Ncolors[] array to indicate choice. */
-/* Return value is total number of colors (product of Ncolors[] values). */
-{
- int nc = cinfo->out_color_components; /* number of color components */
- int max_colors = cinfo->desired_number_of_colors;
- int total_colors, iroot, i, j;
- boolean changed;
- long temp;
- static const int RGB_order[3] = { RGB_GREEN, RGB_RED, RGB_BLUE };
-
- /* We can allocate at least the nc'th root of max_colors per component. */
- /* Compute floor(nc'th root of max_colors). */
- iroot = 1;
- do {
- iroot++;
- temp = iroot; /* set temp = iroot ** nc */
- for (i = 1; i < nc; i++)
- temp *= iroot;
- } while (temp <= (long) max_colors); /* repeat till iroot exceeds root */
- iroot--; /* now iroot = floor(root) */
-
- /* Must have at least 2 color values per component */
- if (iroot < 2)
- ERREXIT1(cinfo, JERR_QUANT_FEW_COLORS, (int) temp);
-
- /* Initialize to iroot color values for each component */
- total_colors = 1;
- for (i = 0; i < nc; i++) {
- Ncolors[i] = iroot;
- total_colors *= iroot;
- }
- /* We may be able to increment the count for one or more components without
- * exceeding max_colors, though we know not all can be incremented.
- * Sometimes, the first component can be incremented more than once!
- * (Example: for 16 colors, we start at 2*2*2, go to 3*2*2, then 4*2*2.)
- * In RGB colorspace, try to increment G first, then R, then B.
- */
- do {
- changed = FALSE;
- for (i = 0; i < nc; i++) {
- j = (cinfo->out_color_space == JCS_RGB ? RGB_order[i] : i);
- /* calculate new total_colors if Ncolors[j] is incremented */
- temp = total_colors / Ncolors[j];
- temp *= Ncolors[j]+1; /* done in long arith to avoid oflo */
- if (temp > (long) max_colors)
- break; /* won't fit, done with this pass */
- Ncolors[j]++; /* OK, apply the increment */
- total_colors = (int) temp;
- changed = TRUE;
- }
- } while (changed);
-
- return total_colors;
-}
-
-
-LOCAL(int)
-output_value (j_decompress_ptr cinfo, int ci, int j, int maxj)
-/* Return j'th output value, where j will range from 0 to maxj */
-/* The output values must fall in 0..MAXJSAMPLE in increasing order */
-{
- /* We always provide values 0 and MAXJSAMPLE for each component;
- * any additional values are equally spaced between these limits.
- * (Forcing the upper and lower values to the limits ensures that
- * dithering can't produce a color outside the selected gamut.)
- */
- return (int) (((INT32) j * MAXJSAMPLE + maxj/2) / maxj);
-}
-
-
-LOCAL(int)
-largest_input_value (j_decompress_ptr cinfo, int ci, int j, int maxj)
-/* Return largest input value that should map to j'th output value */
-/* Must have largest(j=0) >= 0, and largest(j=maxj) >= MAXJSAMPLE */
-{
- /* Breakpoints are halfway between values returned by output_value */
- return (int) (((INT32) (2*j + 1) * MAXJSAMPLE + maxj) / (2*maxj));
-}
-
-
-/*
- * Create the colormap.
- */
-
-LOCAL(void)
-create_colormap (j_decompress_ptr cinfo)
-{
- my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
- JSAMPARRAY colormap; /* Created colormap */
- int total_colors; /* Number of distinct output colors */
- int i,j,k, nci, blksize, blkdist, ptr, val;
-
- /* Select number of colors for each component */
- total_colors = select_ncolors(cinfo, cquantize->Ncolors);
-
- /* Report selected color counts */
- if (cinfo->out_color_components == 3)
- TRACEMS4(cinfo, 1, JTRC_QUANT_3_NCOLORS,
- total_colors, cquantize->Ncolors[0],
- cquantize->Ncolors[1], cquantize->Ncolors[2]);
- else
- TRACEMS1(cinfo, 1, JTRC_QUANT_NCOLORS, total_colors);
-
- /* Allocate and fill in the colormap. */
- /* The colors are ordered in the map in standard row-major order, */
- /* i.e. rightmost (highest-indexed) color changes most rapidly. */
-
- colormap = (*cinfo->mem->alloc_sarray)
- ((j_common_ptr) cinfo, JPOOL_IMAGE,
- (JDIMENSION) total_colors, (JDIMENSION) cinfo->out_color_components);
-
- /* blksize is number of adjacent repeated entries for a component */
- /* blkdist is distance between groups of identical entries for a component */
- blkdist = total_colors;
-
- for (i = 0; i < cinfo->out_color_components; i++) {
- /* fill in colormap entries for i'th color component */
- nci = cquantize->Ncolors[i]; /* # of distinct values for this color */
- blksize = blkdist / nci;
- for (j = 0; j < nci; j++) {
- /* Compute j'th output value (out of nci) for component */
- val = output_value(cinfo, i, j, nci-1);
- /* Fill in all colormap entries that have this value of this component */
- for (ptr = j * blksize; ptr < total_colors; ptr += blkdist) {
- /* fill in blksize entries beginning at ptr */
- for (k = 0; k < blksize; k++)
- colormap[i][ptr+k] = (JSAMPLE) val;
- }
- }
- blkdist = blksize; /* blksize of this color is blkdist of next */
- }
-
- /* Save the colormap in private storage,
- * where it will survive color quantization mode changes.
- */
- cquantize->sv_colormap = colormap;
- cquantize->sv_actual = total_colors;
-}
-
-
-/*
- * Create the color index table.
- */
-
-LOCAL(void)
-create_colorindex (j_decompress_ptr cinfo)
-{
- my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
- JSAMPROW indexptr;
- int i,j,k, nci, blksize, val, pad;
-
- /* For ordered dither, we pad the color index tables by MAXJSAMPLE in
- * each direction (input index values can be -MAXJSAMPLE .. 2*MAXJSAMPLE).
- * This is not necessary in the other dithering modes. However, we
- * flag whether it was done in case user changes dithering mode.
- */
- if (cinfo->dither_mode == JDITHER_ORDERED) {
- pad = MAXJSAMPLE*2;
- cquantize->is_padded = TRUE;
- } else {
- pad = 0;
- cquantize->is_padded = FALSE;
- }
-
- cquantize->colorindex = (*cinfo->mem->alloc_sarray)
- ((j_common_ptr) cinfo, JPOOL_IMAGE,
- (JDIMENSION) (MAXJSAMPLE+1 + pad),
- (JDIMENSION) cinfo->out_color_components);
-
- /* blksize is number of adjacent repeated entries for a component */
- blksize = cquantize->sv_actual;
-
- for (i = 0; i < cinfo->out_color_components; i++) {
- /* fill in colorindex entries for i'th color component */
- nci = cquantize->Ncolors[i]; /* # of distinct values for this color */
- blksize = blksize / nci;
-
- /* adjust colorindex pointers to provide padding at negative indexes. */
- if (pad)
- cquantize->colorindex[i] += MAXJSAMPLE;
-
- /* in loop, val = index of current output value, */
- /* and k = largest j that maps to current val */
- indexptr = cquantize->colorindex[i];
- val = 0;
- k = largest_input_value(cinfo, i, 0, nci-1);
- for (j = 0; j <= MAXJSAMPLE; j++) {
- while (j > k) /* advance val if past boundary */
- k = largest_input_value(cinfo, i, ++val, nci-1);
- /* premultiply so that no multiplication needed in main processing */
- indexptr[j] = (JSAMPLE) (val * blksize);
- }
- /* Pad at both ends if necessary */
- if (pad)
- for (j = 1; j <= MAXJSAMPLE; j++) {
- indexptr[-j] = indexptr[0];
- indexptr[MAXJSAMPLE+j] = indexptr[MAXJSAMPLE];
- }
- }
-}
-
-
-/*
- * Create an ordered-dither array for a component having ncolors
- * distinct output values.
- */
-
-LOCAL(ODITHER_MATRIX_PTR)
-make_odither_array (j_decompress_ptr cinfo, int ncolors)
-{
- ODITHER_MATRIX_PTR odither;
- int j,k;
- INT32 num,den;
-
- odither = (ODITHER_MATRIX_PTR)
- (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
- SIZEOF(ODITHER_MATRIX));
- /* The inter-value distance for this color is MAXJSAMPLE/(ncolors-1).
- * Hence the dither value for the matrix cell with fill order f
- * (f=0..N-1) should be (N-1-2*f)/(2*N) * MAXJSAMPLE/(ncolors-1).
- * On 16-bit-int machine, be careful to avoid overflow.
- */
- den = 2 * ODITHER_CELLS * ((INT32) (ncolors - 1));
- for (j = 0; j < ODITHER_SIZE; j++) {
- for (k = 0; k < ODITHER_SIZE; k++) {
- num = ((INT32) (ODITHER_CELLS-1 - 2*((int)base_dither_matrix[j][k])))
- * MAXJSAMPLE;
- /* Ensure round towards zero despite C's lack of consistency
- * about rounding negative values in integer division...
- */
- odither[j][k] = (int) (num<0 ? -((-num)/den) : num/den);
- }
- }
- return odither;
-}
-
-
-/*
- * Create the ordered-dither tables.
- * Components having the same number of representative colors may
- * share a dither table.
- */
-
-LOCAL(void)
-create_odither_tables (j_decompress_ptr cinfo)
-{
- my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
- ODITHER_MATRIX_PTR odither;
- int i, j, nci;
-
- for (i = 0; i < cinfo->out_color_components; i++) {
- nci = cquantize->Ncolors[i]; /* # of distinct values for this color */
- odither = NULL; /* search for matching prior component */
- for (j = 0; j < i; j++) {
- if (nci == cquantize->Ncolors[j]) {
- odither = cquantize->odither[j];
- break;
- }
- }
- if (odither == NULL) /* need a new table? */
- odither = make_odither_array(cinfo, nci);
- cquantize->odither[i] = odither;
- }
-}
-
-
-/*
- * Map some rows of pixels to the output colormapped representation.
- */
-
-METHODDEF(void)
-color_quantize (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
- JSAMPARRAY output_buf, int num_rows)
-/* General case, no dithering */
-{
- my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
- JSAMPARRAY colorindex = cquantize->colorindex;
- register int pixcode, ci;
- register JSAMPROW ptrin, ptrout;
- int row;
- JDIMENSION col;
- JDIMENSION width = cinfo->output_width;
- register int nc = cinfo->out_color_components;
-
- for (row = 0; row < num_rows; row++) {
- ptrin = input_buf[row];
- ptrout = output_buf[row];
- for (col = width; col > 0; col--) {
- pixcode = 0;
- for (ci = 0; ci < nc; ci++) {
- pixcode += GETJSAMPLE(colorindex[ci][GETJSAMPLE(*ptrin++)]);
- }
- *ptrout++ = (JSAMPLE) pixcode;
- }
- }
-}
-
-
-METHODDEF(void)
-color_quantize3 (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
- JSAMPARRAY output_buf, int num_rows)
-/* Fast path for out_color_components==3, no dithering */
-{
- my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
- register int pixcode;
- register JSAMPROW ptrin, ptrout;
- JSAMPROW colorindex0 = cquantize->colorindex[0];
- JSAMPROW colorindex1 = cquantize->colorindex[1];
- JSAMPROW colorindex2 = cquantize->colorindex[2];
- int row;
- JDIMENSION col;
- JDIMENSION width = cinfo->output_width;
-
- for (row = 0; row < num_rows; row++) {
- ptrin = input_buf[row];
- ptrout = output_buf[row];
- for (col = width; col > 0; col--) {
- pixcode = GETJSAMPLE(colorindex0[GETJSAMPLE(*ptrin++)]);
- pixcode += GETJSAMPLE(colorindex1[GETJSAMPLE(*ptrin++)]);
- pixcode += GETJSAMPLE(colorindex2[GETJSAMPLE(*ptrin++)]);
- *ptrout++ = (JSAMPLE) pixcode;
- }
- }
-}
-
-
-METHODDEF(void)
-quantize_ord_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
- JSAMPARRAY output_buf, int num_rows)
-/* General case, with ordered dithering */
-{
- my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
- register JSAMPROW input_ptr;
- register JSAMPROW output_ptr;
- JSAMPROW colorindex_ci;
- int * dither; /* points to active row of dither matrix */
- int row_index, col_index; /* current indexes into dither matrix */
- int nc = cinfo->out_color_components;
- int ci;
- int row;
- JDIMENSION col;
- JDIMENSION width = cinfo->output_width;
-
- for (row = 0; row < num_rows; row++) {
- /* Initialize output values to 0 so can process components separately */
- FMEMZERO((void FAR *) output_buf[row],
- (size_t) (width * SIZEOF(JSAMPLE)));
- row_index = cquantize->row_index;
- for (ci = 0; ci < nc; ci++) {
- input_ptr = input_buf[row] + ci;
- output_ptr = output_buf[row];
- colorindex_ci = cquantize->colorindex[ci];
- dither = cquantize->odither[ci][row_index];
- col_index = 0;
-
- for (col = width; col > 0; col--) {
- /* Form pixel value + dither, range-limit to 0..MAXJSAMPLE,
- * select output value, accumulate into output code for this pixel.
- * Range-limiting need not be done explicitly, as we have extended
- * the colorindex table to produce the right answers for out-of-range
- * inputs. The maximum dither is +- MAXJSAMPLE; this sets the
- * required amount of padding.
- */
- *output_ptr += colorindex_ci[GETJSAMPLE(*input_ptr)+dither[col_index]];
- input_ptr += nc;
- output_ptr++;
- col_index = (col_index + 1) & ODITHER_MASK;
- }
- }
- /* Advance row index for next row */
- row_index = (row_index + 1) & ODITHER_MASK;
- cquantize->row_index = row_index;
- }
-}
-
-
-METHODDEF(void)
-quantize3_ord_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
- JSAMPARRAY output_buf, int num_rows)
-/* Fast path for out_color_components==3, with ordered dithering */
-{
- my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
- register int pixcode;
- register JSAMPROW input_ptr;
- register JSAMPROW output_ptr;
- JSAMPROW colorindex0 = cquantize->colorindex[0];
- JSAMPROW colorindex1 = cquantize->colorindex[1];
- JSAMPROW colorindex2 = cquantize->colorindex[2];
- int * dither0; /* points to active row of dither matrix */
- int * dither1;
- int * dither2;
- int row_index, col_index; /* current indexes into dither matrix */
- int row;
- JDIMENSION col;
- JDIMENSION width = cinfo->output_width;
-
- for (row = 0; row < num_rows; row++) {
- row_index = cquantize->row_index;
- input_ptr = input_buf[row];
- output_ptr = output_buf[row];
- dither0 = cquantize->odither[0][row_index];
- dither1 = cquantize->odither[1][row_index];
- dither2 = cquantize->odither[2][row_index];
- col_index = 0;
-
- for (col = width; col > 0; col--) {
- pixcode = GETJSAMPLE(colorindex0[GETJSAMPLE(*input_ptr++) +
- dither0[col_index]]);
- pixcode += GETJSAMPLE(colorindex1[GETJSAMPLE(*input_ptr++) +
- dither1[col_index]]);
- pixcode += GETJSAMPLE(colorindex2[GETJSAMPLE(*input_ptr++) +
- dither2[col_index]]);
- *output_ptr++ = (JSAMPLE) pixcode;
- col_index = (col_index + 1) & ODITHER_MASK;
- }
- row_index = (row_index + 1) & ODITHER_MASK;
- cquantize->row_index = row_index;
- }
-}
-
-
-METHODDEF(void)
-quantize_fs_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf,
- JSAMPARRAY output_buf, int num_rows)
-/* General case, with Floyd-Steinberg dithering */
-{
- my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
- register LOCFSERROR cur; /* current error or pixel value */
- LOCFSERROR belowerr; /* error for pixel below cur */
- LOCFSERROR bpreverr; /* error for below/prev col */
- LOCFSERROR bnexterr; /* error for below/next col */
- LOCFSERROR delta;
- register FSERRPTR errorptr; /* => fserrors[] at column before current */
- register JSAMPROW input_ptr;
- register JSAMPROW output_ptr;
- JSAMPROW colorindex_ci;
- JSAMPROW colormap_ci;
- int pixcode;
- int nc = cinfo->out_color_components;
- int dir; /* 1 for left-to-right, -1 for right-to-left */
- int dirnc; /* dir * nc */
- int ci;
- int row;
- JDIMENSION col;
- JDIMENSION width = cinfo->output_width;
- JSAMPLE *range_limit = cinfo->sample_range_limit;
- SHIFT_TEMPS
-
- for (row = 0; row < num_rows; row++) {
- /* Initialize output values to 0 so can process components separately */
- FMEMZERO((void FAR *) output_buf[row],
- (size_t) (width * SIZEOF(JSAMPLE)));
- for (ci = 0; ci < nc; ci++) {
- input_ptr = input_buf[row] + ci;
- output_ptr = output_buf[row];
- if (cquantize->on_odd_row) {
- /* work right to left in this row */
- input_ptr += (width-1) * nc; /* so point to rightmost pixel */
- output_ptr += width-1;
- dir = -1;
- dirnc = -nc;
- errorptr = cquantize->fserrors[ci] + (width+1); /* => entry after last column */
- } else {
- /* work left to right in this row */
- dir = 1;
- dirnc = nc;
- errorptr = cquantize->fserrors[ci]; /* => entry before first column */
- }
- colorindex_ci = cquantize->colorindex[ci];
- colormap_ci = cquantize->sv_colormap[ci];
- /* Preset error values: no error propagated to first pixel from left */
- cur = 0;
- /* and no error propagated to row below yet */
- belowerr = bpreverr = 0;
-
- for (col = width; col > 0; col--) {
- /* cur holds the error propagated from the previous pixel on the
- * current line. Add the error propagated from the previous line
- * to form the complete error correction term for this pixel, and
- * round the error term (which is expressed * 16) to an integer.
- * RIGHT_SHIFT rounds towards minus infinity, so adding 8 is correct
- * for either sign of the error value.
- * Note: errorptr points to *previous* column's array entry.
- */
- cur = RIGHT_SHIFT(cur + errorptr[dir] + 8, 4);
- /* Form pixel value + error, and range-limit to 0..MAXJSAMPLE.
- * The maximum error is +- MAXJSAMPLE; this sets the required size
- * of the range_limit array.
- */
- cur += GETJSAMPLE(*input_ptr);
- cur = GETJSAMPLE(range_limit[cur]);
- /* Select output value, accumulate into output code for this pixel */
- pixcode = GETJSAMPLE(colorindex_ci[cur]);
- *output_ptr += (JSAMPLE) pixcode;
- /* Compute actual representation error at this pixel */
- /* Note: we can do this even though we don't have the final */
- /* pixel code, because the colormap is orthogonal. */
- cur -= GETJSAMPLE(colormap_ci[pixcode]);
- /* Compute error fractions to be propagated to adjacent pixels.
- * Add these into the running sums, and simultaneously shift the
- * next-line error sums left by 1 column.
- */
- bnexterr = cur;
- delta = cur * 2;
- cur += delta; /* form error * 3 */
- errorptr[0] = (FSERROR) (bpreverr + cur);
- cur += delta; /* form error * 5 */
- bpreverr = belowerr + cur;
- belowerr = bnexterr;
- cur += delta; /* form error * 7 */
- /* At this point cur contains the 7/16 error value to be propagated
- * to the next pixel on the current line, and all the errors for the
- * next line have been shifted over. We are therefore ready to move on.
- */
- input_ptr += dirnc; /* advance input ptr to next column */
- output_ptr += dir; /* advance output ptr to next column */
- errorptr += dir; /* advance errorptr to current column */
- }
- /* Post-loop cleanup: we must unload the final error value into the
- * final fserrors[] entry. Note we need not unload belowerr because
- * it is for the dummy column before or after the actual array.
- */
- errorptr[0] = (FSERROR) bpreverr; /* unload prev err into array */
- }
- cquantize->on_odd_row = (cquantize->on_odd_row ? FALSE : TRUE);
- }
-}
-
-
-/*
- * Allocate workspace for Floyd-Steinberg errors.
- */
-
-LOCAL(void)
-alloc_fs_workspace (j_decompress_ptr cinfo)
-{
- my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
- size_t arraysize;
- int i;
-
- arraysize = (size_t) ((cinfo->output_width + 2) * SIZEOF(FSERROR));
- for (i = 0; i < cinfo->out_color_components; i++) {
- cquantize->fserrors[i] = (FSERRPTR)
- (*cinfo->mem->alloc_large)((j_common_ptr) cinfo, JPOOL_IMAGE, arraysize);
- }
-}
-
-
-/*
- * Initialize for one-pass color quantization.
- */
-
-METHODDEF(void)
-start_pass_1_quant (j_decompress_ptr cinfo, boolean is_pre_scan)
-{
- my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize;
- size_t arraysize;
- int i;
-
- /* Install my colormap. */
- cinfo->colormap = cquantize->sv_colormap;
- cinfo->actual_number_of_colors = cquantize->sv_actual;
-
- /* Initialize for desired dithering mode. */
- switch (cinfo->dither_mode) {
- case JDITHER_NONE:
- if (cinfo->out_color_components == 3)
- cquantize->pub.color_quantize = color_quantize3;
- else
- cquantize->pub.color_quantize = color_quantize;
- break;
- case JDITHER_ORDERED:
- if (cinfo->out_color_components == 3)
- cquantize->pub.color_quantize = quantize3_ord_dither;
- else
- cquantize->pub.color_quantize = quantize_ord_dither;
- cquantize->row_index = 0; /* initialize state for ordered dither */
- /* If user changed to ordered dither from another mode,
- * we must recreate the color index table with padding.
- * This will cost extra space, but probably isn't very likely.
- */
- if (! cquantize->is_padded)
- create_colorindex(cinfo);
- /* Create ordered-dither tables if we didn't already. */
- if (cquantize->odither[0] == NULL)
- create_odither_tables(cinfo);
- break;
- case JDITHER_FS:
- cquantize->pub.color_quantize = quantize_fs_dither;
- cquantize->on_odd_row = FALSE; /* initialize state for F-S dither */
- /* Allocate Floyd-Steinberg workspace if didn't already. */
- if (cquantize->fserrors[0] == NULL)
- alloc_fs_workspace(cinfo);
- /* Initialize the propagated errors to zero. */
- arraysize = (size_t) ((cinfo->output_width + 2) * SIZEOF(FSERROR));
- for (i = 0; i < cinfo->out_color_components; i++)
- FMEMZERO((void FAR *) cquantize->fserrors[i], arraysize);
- break;
- default:
- ERREXIT(cinfo, JERR_NOT_COMPILED);
- break;
- }
-}
-
-
-/*
- * Finish up at the end of the pass.
- */
-
-METHODDEF(void)
-finish_pass_1_quant (j_decompress_ptr cinfo)
-{
- /* no work in 1-pass case */
-}
-
-
-/*
- * Switch to a new external colormap between output passes.
- * Shouldn't get to this module!
- */
-
-METHODDEF(void)
-new_color_map_1_quant (j_decompress_ptr cinfo)
-{
- ERREXIT(cinfo, JERR_MODE_CHANGE);
-}
-
-
-/*
- * Module initialization routine for 1-pass color quantization.
- */
-
-GLOBAL(void)
-jinit_1pass_quantizer (j_decompress_ptr cinfo)
-{
- my_cquantize_ptr cquantize;
-
- cquantize = (my_cquantize_ptr)
- (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE,
- SIZEOF(my_cquantizer));
- cinfo->cquantize = (struct jpeg_color_quantizer *) cquantize;
- cquantize->pub.start_pass = start_pass_1_quant;
- cquantize->pub.finish_pass = finish_pass_1_quant;
- cquantize->pub.new_color_map = new_color_map_1_quant;
- cquantize->fserrors[0] = NULL; /* Flag FS workspace not allocated */
- cquantize->odither[0] = NULL; /* Also flag odither arrays not allocated */
-
- /* Make sure my internal arrays won't overflow */
- if (cinfo->out_color_components > MAX_Q_COMPS)
- ERREXIT1(cinfo, JERR_QUANT_COMPONENTS, MAX_Q_COMPS);
- /* Make sure colormap indexes can be represented by JSAMPLEs */
- if (cinfo->desired_number_of_colors > (MAXJSAMPLE+1))
- ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, MAXJSAMPLE+1);
-
- /* Create the colormap and color index table. */
- create_colormap(cinfo);
- create_colorindex(cinfo);
-
- /* Allocate Floyd-Steinberg workspace now if requested.
- * We do this now since it is FAR storage and may affect the memory
- * manager's space calculations. If the user changes to FS dither
- * mode in a later pass, we will allocate the space then, and will
- * possibly overrun the max_memory_to_use setting.
- */
- if (cinfo->dither_mode == JDITHER_FS)
- alloc_fs_workspace(cinfo);
-}
-
-#endif /* QUANT_1PASS_SUPPORTED */
projects / reactos.git / blobdiff