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