michael@0: /* michael@0: * jquant1.c michael@0: * michael@0: * This file was part of the Independent JPEG Group's software: michael@0: * Copyright (C) 1991-1996, Thomas G. Lane. michael@0: * libjpeg-turbo Modifications: michael@0: * Copyright (C) 2009, D. R. Commander michael@0: * For conditions of distribution and use, see the accompanying README file. michael@0: * michael@0: * This file contains 1-pass color quantization (color mapping) routines. michael@0: * These routines provide mapping to a fixed color map using equally spaced michael@0: * color values. Optional Floyd-Steinberg or ordered dithering is available. michael@0: */ michael@0: michael@0: #define JPEG_INTERNALS michael@0: #include "jinclude.h" michael@0: #include "jpeglib.h" michael@0: michael@0: #ifdef QUANT_1PASS_SUPPORTED michael@0: michael@0: michael@0: /* michael@0: * The main purpose of 1-pass quantization is to provide a fast, if not very michael@0: * high quality, colormapped output capability. A 2-pass quantizer usually michael@0: * gives better visual quality; however, for quantized grayscale output this michael@0: * quantizer is perfectly adequate. Dithering is highly recommended with this michael@0: * quantizer, though you can turn it off if you really want to. michael@0: * michael@0: * In 1-pass quantization the colormap must be chosen in advance of seeing the michael@0: * image. We use a map consisting of all combinations of Ncolors[i] color michael@0: * values for the i'th component. The Ncolors[] values are chosen so that michael@0: * their product, the total number of colors, is no more than that requested. michael@0: * (In most cases, the product will be somewhat less.) michael@0: * michael@0: * Since the colormap is orthogonal, the representative value for each color michael@0: * component can be determined without considering the other components; michael@0: * then these indexes can be combined into a colormap index by a standard michael@0: * N-dimensional-array-subscript calculation. Most of the arithmetic involved michael@0: * can be precalculated and stored in the lookup table colorindex[]. michael@0: * colorindex[i][j] maps pixel value j in component i to the nearest michael@0: * representative value (grid plane) for that component; this index is michael@0: * multiplied by the array stride for component i, so that the michael@0: * index of the colormap entry closest to a given pixel value is just michael@0: * sum( colorindex[component-number][pixel-component-value] ) michael@0: * Aside from being fast, this scheme allows for variable spacing between michael@0: * representative values with no additional lookup cost. michael@0: * michael@0: * If gamma correction has been applied in color conversion, it might be wise michael@0: * to adjust the color grid spacing so that the representative colors are michael@0: * equidistant in linear space. At this writing, gamma correction is not michael@0: * implemented by jdcolor, so nothing is done here. michael@0: */ michael@0: michael@0: michael@0: /* Declarations for ordered dithering. michael@0: * michael@0: * We use a standard 16x16 ordered dither array. The basic concept of ordered michael@0: * dithering is described in many references, for instance Dale Schumacher's michael@0: * chapter II.2 of Graphics Gems II (James Arvo, ed. Academic Press, 1991). michael@0: * In place of Schumacher's comparisons against a "threshold" value, we add a michael@0: * "dither" value to the input pixel and then round the result to the nearest michael@0: * output value. The dither value is equivalent to (0.5 - threshold) times michael@0: * the distance between output values. For ordered dithering, we assume that michael@0: * the output colors are equally spaced; if not, results will probably be michael@0: * worse, since the dither may be too much or too little at a given point. michael@0: * michael@0: * The normal calculation would be to form pixel value + dither, range-limit michael@0: * this to 0..MAXJSAMPLE, and then index into the colorindex table as usual. michael@0: * We can skip the separate range-limiting step by extending the colorindex michael@0: * table in both directions. michael@0: */ michael@0: michael@0: #define ODITHER_SIZE 16 /* dimension of dither matrix */ michael@0: /* NB: if ODITHER_SIZE is not a power of 2, ODITHER_MASK uses will break */ michael@0: #define ODITHER_CELLS (ODITHER_SIZE*ODITHER_SIZE) /* # cells in matrix */ michael@0: #define ODITHER_MASK (ODITHER_SIZE-1) /* mask for wrapping around counters */ michael@0: michael@0: typedef int ODITHER_MATRIX[ODITHER_SIZE][ODITHER_SIZE]; michael@0: typedef int (*ODITHER_MATRIX_PTR)[ODITHER_SIZE]; michael@0: michael@0: static const UINT8 base_dither_matrix[ODITHER_SIZE][ODITHER_SIZE] = { michael@0: /* Bayer's order-4 dither array. Generated by the code given in michael@0: * Stephen Hawley's article "Ordered Dithering" in Graphics Gems I. michael@0: * The values in this array must range from 0 to ODITHER_CELLS-1. michael@0: */ michael@0: { 0,192, 48,240, 12,204, 60,252, 3,195, 51,243, 15,207, 63,255 }, michael@0: { 128, 64,176,112,140, 76,188,124,131, 67,179,115,143, 79,191,127 }, michael@0: { 32,224, 16,208, 44,236, 28,220, 35,227, 19,211, 47,239, 31,223 }, michael@0: { 160, 96,144, 80,172,108,156, 92,163, 99,147, 83,175,111,159, 95 }, michael@0: { 8,200, 56,248, 4,196, 52,244, 11,203, 59,251, 7,199, 55,247 }, michael@0: { 136, 72,184,120,132, 68,180,116,139, 75,187,123,135, 71,183,119 }, michael@0: { 40,232, 24,216, 36,228, 20,212, 43,235, 27,219, 39,231, 23,215 }, michael@0: { 168,104,152, 88,164,100,148, 84,171,107,155, 91,167,103,151, 87 }, michael@0: { 2,194, 50,242, 14,206, 62,254, 1,193, 49,241, 13,205, 61,253 }, michael@0: { 130, 66,178,114,142, 78,190,126,129, 65,177,113,141, 77,189,125 }, michael@0: { 34,226, 18,210, 46,238, 30,222, 33,225, 17,209, 45,237, 29,221 }, michael@0: { 162, 98,146, 82,174,110,158, 94,161, 97,145, 81,173,109,157, 93 }, michael@0: { 10,202, 58,250, 6,198, 54,246, 9,201, 57,249, 5,197, 53,245 }, michael@0: { 138, 74,186,122,134, 70,182,118,137, 73,185,121,133, 69,181,117 }, michael@0: { 42,234, 26,218, 38,230, 22,214, 41,233, 25,217, 37,229, 21,213 }, michael@0: { 170,106,154, 90,166,102,150, 86,169,105,153, 89,165,101,149, 85 } michael@0: }; michael@0: michael@0: michael@0: /* Declarations for Floyd-Steinberg dithering. michael@0: * michael@0: * Errors are accumulated into the array fserrors[], at a resolution of michael@0: * 1/16th of a pixel count. The error at a given pixel is propagated michael@0: * to its not-yet-processed neighbors using the standard F-S fractions, michael@0: * ... (here) 7/16 michael@0: * 3/16 5/16 1/16 michael@0: * We work left-to-right on even rows, right-to-left on odd rows. michael@0: * michael@0: * We can get away with a single array (holding one row's worth of errors) michael@0: * by using it to store the current row's errors at pixel columns not yet michael@0: * processed, but the next row's errors at columns already processed. We michael@0: * need only a few extra variables to hold the errors immediately around the michael@0: * current column. (If we are lucky, those variables are in registers, but michael@0: * even if not, they're probably cheaper to access than array elements are.) michael@0: * michael@0: * The fserrors[] array is indexed [component#][position]. michael@0: * We provide (#columns + 2) entries per component; the extra entry at each michael@0: * end saves us from special-casing the first and last pixels. michael@0: * michael@0: * Note: on a wide image, we might not have enough room in a PC's near data michael@0: * segment to hold the error array; so it is allocated with alloc_large. michael@0: */ michael@0: michael@0: #if BITS_IN_JSAMPLE == 8 michael@0: typedef INT16 FSERROR; /* 16 bits should be enough */ michael@0: typedef int LOCFSERROR; /* use 'int' for calculation temps */ michael@0: #else michael@0: typedef INT32 FSERROR; /* may need more than 16 bits */ michael@0: typedef INT32 LOCFSERROR; /* be sure calculation temps are big enough */ michael@0: #endif michael@0: michael@0: typedef FSERROR FAR *FSERRPTR; /* pointer to error array (in FAR storage!) */ michael@0: michael@0: michael@0: /* Private subobject */ michael@0: michael@0: #define MAX_Q_COMPS 4 /* max components I can handle */ michael@0: michael@0: typedef struct { michael@0: struct jpeg_color_quantizer pub; /* public fields */ michael@0: michael@0: /* Initially allocated colormap is saved here */ michael@0: JSAMPARRAY sv_colormap; /* The color map as a 2-D pixel array */ michael@0: int sv_actual; /* number of entries in use */ michael@0: michael@0: JSAMPARRAY colorindex; /* Precomputed mapping for speed */ michael@0: /* colorindex[i][j] = index of color closest to pixel value j in component i, michael@0: * premultiplied as described above. Since colormap indexes must fit into michael@0: * JSAMPLEs, the entries of this array will too. michael@0: */ michael@0: boolean is_padded; /* is the colorindex padded for odither? */ michael@0: michael@0: int Ncolors[MAX_Q_COMPS]; /* # of values alloced to each component */ michael@0: michael@0: /* Variables for ordered dithering */ michael@0: int row_index; /* cur row's vertical index in dither matrix */ michael@0: ODITHER_MATRIX_PTR odither[MAX_Q_COMPS]; /* one dither array per component */ michael@0: michael@0: /* Variables for Floyd-Steinberg dithering */ michael@0: FSERRPTR fserrors[MAX_Q_COMPS]; /* accumulated errors */ michael@0: boolean on_odd_row; /* flag to remember which row we are on */ michael@0: } my_cquantizer; michael@0: michael@0: typedef my_cquantizer * my_cquantize_ptr; michael@0: michael@0: michael@0: /* michael@0: * Policy-making subroutines for create_colormap and create_colorindex. michael@0: * These routines determine the colormap to be used. The rest of the module michael@0: * only assumes that the colormap is orthogonal. michael@0: * michael@0: * * select_ncolors decides how to divvy up the available colors michael@0: * among the components. michael@0: * * output_value defines the set of representative values for a component. michael@0: * * largest_input_value defines the mapping from input values to michael@0: * representative values for a component. michael@0: * Note that the latter two routines may impose different policies for michael@0: * different components, though this is not currently done. michael@0: */ michael@0: michael@0: michael@0: LOCAL(int) michael@0: select_ncolors (j_decompress_ptr cinfo, int Ncolors[]) michael@0: /* Determine allocation of desired colors to components, */ michael@0: /* and fill in Ncolors[] array to indicate choice. */ michael@0: /* Return value is total number of colors (product of Ncolors[] values). */ michael@0: { michael@0: int nc = cinfo->out_color_components; /* number of color components */ michael@0: int max_colors = cinfo->desired_number_of_colors; michael@0: int total_colors, iroot, i, j; michael@0: boolean changed; michael@0: long temp; michael@0: int RGB_order[3] = { RGB_GREEN, RGB_RED, RGB_BLUE }; michael@0: RGB_order[0] = rgb_green[cinfo->out_color_space]; michael@0: RGB_order[1] = rgb_red[cinfo->out_color_space]; michael@0: RGB_order[2] = rgb_blue[cinfo->out_color_space]; michael@0: michael@0: /* We can allocate at least the nc'th root of max_colors per component. */ michael@0: /* Compute floor(nc'th root of max_colors). */ michael@0: iroot = 1; michael@0: do { michael@0: iroot++; michael@0: temp = iroot; /* set temp = iroot ** nc */ michael@0: for (i = 1; i < nc; i++) michael@0: temp *= iroot; michael@0: } while (temp <= (long) max_colors); /* repeat till iroot exceeds root */ michael@0: iroot--; /* now iroot = floor(root) */ michael@0: michael@0: /* Must have at least 2 color values per component */ michael@0: if (iroot < 2) michael@0: ERREXIT1(cinfo, JERR_QUANT_FEW_COLORS, (int) temp); michael@0: michael@0: /* Initialize to iroot color values for each component */ michael@0: total_colors = 1; michael@0: for (i = 0; i < nc; i++) { michael@0: Ncolors[i] = iroot; michael@0: total_colors *= iroot; michael@0: } michael@0: /* We may be able to increment the count for one or more components without michael@0: * exceeding max_colors, though we know not all can be incremented. michael@0: * Sometimes, the first component can be incremented more than once! michael@0: * (Example: for 16 colors, we start at 2*2*2, go to 3*2*2, then 4*2*2.) michael@0: * In RGB colorspace, try to increment G first, then R, then B. michael@0: */ michael@0: do { michael@0: changed = FALSE; michael@0: for (i = 0; i < nc; i++) { michael@0: j = (cinfo->out_color_space == JCS_RGB ? RGB_order[i] : i); michael@0: /* calculate new total_colors if Ncolors[j] is incremented */ michael@0: temp = total_colors / Ncolors[j]; michael@0: temp *= Ncolors[j]+1; /* done in long arith to avoid oflo */ michael@0: if (temp > (long) max_colors) michael@0: break; /* won't fit, done with this pass */ michael@0: Ncolors[j]++; /* OK, apply the increment */ michael@0: total_colors = (int) temp; michael@0: changed = TRUE; michael@0: } michael@0: } while (changed); michael@0: michael@0: return total_colors; michael@0: } michael@0: michael@0: michael@0: LOCAL(int) michael@0: output_value (j_decompress_ptr cinfo, int ci, int j, int maxj) michael@0: /* Return j'th output value, where j will range from 0 to maxj */ michael@0: /* The output values must fall in 0..MAXJSAMPLE in increasing order */ michael@0: { michael@0: /* We always provide values 0 and MAXJSAMPLE for each component; michael@0: * any additional values are equally spaced between these limits. michael@0: * (Forcing the upper and lower values to the limits ensures that michael@0: * dithering can't produce a color outside the selected gamut.) michael@0: */ michael@0: return (int) (((INT32) j * MAXJSAMPLE + maxj/2) / maxj); michael@0: } michael@0: michael@0: michael@0: LOCAL(int) michael@0: largest_input_value (j_decompress_ptr cinfo, int ci, int j, int maxj) michael@0: /* Return largest input value that should map to j'th output value */ michael@0: /* Must have largest(j=0) >= 0, and largest(j=maxj) >= MAXJSAMPLE */ michael@0: { michael@0: /* Breakpoints are halfway between values returned by output_value */ michael@0: return (int) (((INT32) (2*j + 1) * MAXJSAMPLE + maxj) / (2*maxj)); michael@0: } michael@0: michael@0: michael@0: /* michael@0: * Create the colormap. michael@0: */ michael@0: michael@0: LOCAL(void) michael@0: create_colormap (j_decompress_ptr cinfo) michael@0: { michael@0: my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; michael@0: JSAMPARRAY colormap; /* Created colormap */ michael@0: int total_colors; /* Number of distinct output colors */ michael@0: int i,j,k, nci, blksize, blkdist, ptr, val; michael@0: michael@0: /* Select number of colors for each component */ michael@0: total_colors = select_ncolors(cinfo, cquantize->Ncolors); michael@0: michael@0: /* Report selected color counts */ michael@0: if (cinfo->out_color_components == 3) michael@0: TRACEMS4(cinfo, 1, JTRC_QUANT_3_NCOLORS, michael@0: total_colors, cquantize->Ncolors[0], michael@0: cquantize->Ncolors[1], cquantize->Ncolors[2]); michael@0: else michael@0: TRACEMS1(cinfo, 1, JTRC_QUANT_NCOLORS, total_colors); michael@0: michael@0: /* Allocate and fill in the colormap. */ michael@0: /* The colors are ordered in the map in standard row-major order, */ michael@0: /* i.e. rightmost (highest-indexed) color changes most rapidly. */ michael@0: michael@0: colormap = (*cinfo->mem->alloc_sarray) michael@0: ((j_common_ptr) cinfo, JPOOL_IMAGE, michael@0: (JDIMENSION) total_colors, (JDIMENSION) cinfo->out_color_components); michael@0: michael@0: /* blksize is number of adjacent repeated entries for a component */ michael@0: /* blkdist is distance between groups of identical entries for a component */ michael@0: blkdist = total_colors; michael@0: michael@0: for (i = 0; i < cinfo->out_color_components; i++) { michael@0: /* fill in colormap entries for i'th color component */ michael@0: nci = cquantize->Ncolors[i]; /* # of distinct values for this color */ michael@0: blksize = blkdist / nci; michael@0: for (j = 0; j < nci; j++) { michael@0: /* Compute j'th output value (out of nci) for component */ michael@0: val = output_value(cinfo, i, j, nci-1); michael@0: /* Fill in all colormap entries that have this value of this component */ michael@0: for (ptr = j * blksize; ptr < total_colors; ptr += blkdist) { michael@0: /* fill in blksize entries beginning at ptr */ michael@0: for (k = 0; k < blksize; k++) michael@0: colormap[i][ptr+k] = (JSAMPLE) val; michael@0: } michael@0: } michael@0: blkdist = blksize; /* blksize of this color is blkdist of next */ michael@0: } michael@0: michael@0: /* Save the colormap in private storage, michael@0: * where it will survive color quantization mode changes. michael@0: */ michael@0: cquantize->sv_colormap = colormap; michael@0: cquantize->sv_actual = total_colors; michael@0: } michael@0: michael@0: michael@0: /* michael@0: * Create the color index table. michael@0: */ michael@0: michael@0: LOCAL(void) michael@0: create_colorindex (j_decompress_ptr cinfo) michael@0: { michael@0: my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; michael@0: JSAMPROW indexptr; michael@0: int i,j,k, nci, blksize, val, pad; michael@0: michael@0: /* For ordered dither, we pad the color index tables by MAXJSAMPLE in michael@0: * each direction (input index values can be -MAXJSAMPLE .. 2*MAXJSAMPLE). michael@0: * This is not necessary in the other dithering modes. However, we michael@0: * flag whether it was done in case user changes dithering mode. michael@0: */ michael@0: if (cinfo->dither_mode == JDITHER_ORDERED) { michael@0: pad = MAXJSAMPLE*2; michael@0: cquantize->is_padded = TRUE; michael@0: } else { michael@0: pad = 0; michael@0: cquantize->is_padded = FALSE; michael@0: } michael@0: michael@0: cquantize->colorindex = (*cinfo->mem->alloc_sarray) michael@0: ((j_common_ptr) cinfo, JPOOL_IMAGE, michael@0: (JDIMENSION) (MAXJSAMPLE+1 + pad), michael@0: (JDIMENSION) cinfo->out_color_components); michael@0: michael@0: /* blksize is number of adjacent repeated entries for a component */ michael@0: blksize = cquantize->sv_actual; michael@0: michael@0: for (i = 0; i < cinfo->out_color_components; i++) { michael@0: /* fill in colorindex entries for i'th color component */ michael@0: nci = cquantize->Ncolors[i]; /* # of distinct values for this color */ michael@0: blksize = blksize / nci; michael@0: michael@0: /* adjust colorindex pointers to provide padding at negative indexes. */ michael@0: if (pad) michael@0: cquantize->colorindex[i] += MAXJSAMPLE; michael@0: michael@0: /* in loop, val = index of current output value, */ michael@0: /* and k = largest j that maps to current val */ michael@0: indexptr = cquantize->colorindex[i]; michael@0: val = 0; michael@0: k = largest_input_value(cinfo, i, 0, nci-1); michael@0: for (j = 0; j <= MAXJSAMPLE; j++) { michael@0: while (j > k) /* advance val if past boundary */ michael@0: k = largest_input_value(cinfo, i, ++val, nci-1); michael@0: /* premultiply so that no multiplication needed in main processing */ michael@0: indexptr[j] = (JSAMPLE) (val * blksize); michael@0: } michael@0: /* Pad at both ends if necessary */ michael@0: if (pad) michael@0: for (j = 1; j <= MAXJSAMPLE; j++) { michael@0: indexptr[-j] = indexptr[0]; michael@0: indexptr[MAXJSAMPLE+j] = indexptr[MAXJSAMPLE]; michael@0: } michael@0: } michael@0: } michael@0: michael@0: michael@0: /* michael@0: * Create an ordered-dither array for a component having ncolors michael@0: * distinct output values. michael@0: */ michael@0: michael@0: LOCAL(ODITHER_MATRIX_PTR) michael@0: make_odither_array (j_decompress_ptr cinfo, int ncolors) michael@0: { michael@0: ODITHER_MATRIX_PTR odither; michael@0: int j,k; michael@0: INT32 num,den; michael@0: michael@0: odither = (ODITHER_MATRIX_PTR) michael@0: (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, michael@0: SIZEOF(ODITHER_MATRIX)); michael@0: /* The inter-value distance for this color is MAXJSAMPLE/(ncolors-1). michael@0: * Hence the dither value for the matrix cell with fill order f michael@0: * (f=0..N-1) should be (N-1-2*f)/(2*N) * MAXJSAMPLE/(ncolors-1). michael@0: * On 16-bit-int machine, be careful to avoid overflow. michael@0: */ michael@0: den = 2 * ODITHER_CELLS * ((INT32) (ncolors - 1)); michael@0: for (j = 0; j < ODITHER_SIZE; j++) { michael@0: for (k = 0; k < ODITHER_SIZE; k++) { michael@0: num = ((INT32) (ODITHER_CELLS-1 - 2*((int)base_dither_matrix[j][k]))) michael@0: * MAXJSAMPLE; michael@0: /* Ensure round towards zero despite C's lack of consistency michael@0: * about rounding negative values in integer division... michael@0: */ michael@0: odither[j][k] = (int) (num<0 ? -((-num)/den) : num/den); michael@0: } michael@0: } michael@0: return odither; michael@0: } michael@0: michael@0: michael@0: /* michael@0: * Create the ordered-dither tables. michael@0: * Components having the same number of representative colors may michael@0: * share a dither table. michael@0: */ michael@0: michael@0: LOCAL(void) michael@0: create_odither_tables (j_decompress_ptr cinfo) michael@0: { michael@0: my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; michael@0: ODITHER_MATRIX_PTR odither; michael@0: int i, j, nci; michael@0: michael@0: for (i = 0; i < cinfo->out_color_components; i++) { michael@0: nci = cquantize->Ncolors[i]; /* # of distinct values for this color */ michael@0: odither = NULL; /* search for matching prior component */ michael@0: for (j = 0; j < i; j++) { michael@0: if (nci == cquantize->Ncolors[j]) { michael@0: odither = cquantize->odither[j]; michael@0: break; michael@0: } michael@0: } michael@0: if (odither == NULL) /* need a new table? */ michael@0: odither = make_odither_array(cinfo, nci); michael@0: cquantize->odither[i] = odither; michael@0: } michael@0: } michael@0: michael@0: michael@0: /* michael@0: * Map some rows of pixels to the output colormapped representation. michael@0: */ michael@0: michael@0: METHODDEF(void) michael@0: color_quantize (j_decompress_ptr cinfo, JSAMPARRAY input_buf, michael@0: JSAMPARRAY output_buf, int num_rows) michael@0: /* General case, no dithering */ michael@0: { michael@0: my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; michael@0: JSAMPARRAY colorindex = cquantize->colorindex; michael@0: register int pixcode, ci; michael@0: register JSAMPROW ptrin, ptrout; michael@0: int row; michael@0: JDIMENSION col; michael@0: JDIMENSION width = cinfo->output_width; michael@0: register int nc = cinfo->out_color_components; michael@0: michael@0: for (row = 0; row < num_rows; row++) { michael@0: ptrin = input_buf[row]; michael@0: ptrout = output_buf[row]; michael@0: for (col = width; col > 0; col--) { michael@0: pixcode = 0; michael@0: for (ci = 0; ci < nc; ci++) { michael@0: pixcode += GETJSAMPLE(colorindex[ci][GETJSAMPLE(*ptrin++)]); michael@0: } michael@0: *ptrout++ = (JSAMPLE) pixcode; michael@0: } michael@0: } michael@0: } michael@0: michael@0: michael@0: METHODDEF(void) michael@0: color_quantize3 (j_decompress_ptr cinfo, JSAMPARRAY input_buf, michael@0: JSAMPARRAY output_buf, int num_rows) michael@0: /* Fast path for out_color_components==3, no dithering */ michael@0: { michael@0: my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; michael@0: register int pixcode; michael@0: register JSAMPROW ptrin, ptrout; michael@0: JSAMPROW colorindex0 = cquantize->colorindex[0]; michael@0: JSAMPROW colorindex1 = cquantize->colorindex[1]; michael@0: JSAMPROW colorindex2 = cquantize->colorindex[2]; michael@0: int row; michael@0: JDIMENSION col; michael@0: JDIMENSION width = cinfo->output_width; michael@0: michael@0: for (row = 0; row < num_rows; row++) { michael@0: ptrin = input_buf[row]; michael@0: ptrout = output_buf[row]; michael@0: for (col = width; col > 0; col--) { michael@0: pixcode = GETJSAMPLE(colorindex0[GETJSAMPLE(*ptrin++)]); michael@0: pixcode += GETJSAMPLE(colorindex1[GETJSAMPLE(*ptrin++)]); michael@0: pixcode += GETJSAMPLE(colorindex2[GETJSAMPLE(*ptrin++)]); michael@0: *ptrout++ = (JSAMPLE) pixcode; michael@0: } michael@0: } michael@0: } michael@0: michael@0: michael@0: METHODDEF(void) michael@0: quantize_ord_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf, michael@0: JSAMPARRAY output_buf, int num_rows) michael@0: /* General case, with ordered dithering */ michael@0: { michael@0: my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; michael@0: register JSAMPROW input_ptr; michael@0: register JSAMPROW output_ptr; michael@0: JSAMPROW colorindex_ci; michael@0: int * dither; /* points to active row of dither matrix */ michael@0: int row_index, col_index; /* current indexes into dither matrix */ michael@0: int nc = cinfo->out_color_components; michael@0: int ci; michael@0: int row; michael@0: JDIMENSION col; michael@0: JDIMENSION width = cinfo->output_width; michael@0: michael@0: for (row = 0; row < num_rows; row++) { michael@0: /* Initialize output values to 0 so can process components separately */ michael@0: jzero_far((void FAR *) output_buf[row], michael@0: (size_t) (width * SIZEOF(JSAMPLE))); michael@0: row_index = cquantize->row_index; michael@0: for (ci = 0; ci < nc; ci++) { michael@0: input_ptr = input_buf[row] + ci; michael@0: output_ptr = output_buf[row]; michael@0: colorindex_ci = cquantize->colorindex[ci]; michael@0: dither = cquantize->odither[ci][row_index]; michael@0: col_index = 0; michael@0: michael@0: for (col = width; col > 0; col--) { michael@0: /* Form pixel value + dither, range-limit to 0..MAXJSAMPLE, michael@0: * select output value, accumulate into output code for this pixel. michael@0: * Range-limiting need not be done explicitly, as we have extended michael@0: * the colorindex table to produce the right answers for out-of-range michael@0: * inputs. The maximum dither is +- MAXJSAMPLE; this sets the michael@0: * required amount of padding. michael@0: */ michael@0: *output_ptr += colorindex_ci[GETJSAMPLE(*input_ptr)+dither[col_index]]; michael@0: input_ptr += nc; michael@0: output_ptr++; michael@0: col_index = (col_index + 1) & ODITHER_MASK; michael@0: } michael@0: } michael@0: /* Advance row index for next row */ michael@0: row_index = (row_index + 1) & ODITHER_MASK; michael@0: cquantize->row_index = row_index; michael@0: } michael@0: } michael@0: michael@0: michael@0: METHODDEF(void) michael@0: quantize3_ord_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf, michael@0: JSAMPARRAY output_buf, int num_rows) michael@0: /* Fast path for out_color_components==3, with ordered dithering */ michael@0: { michael@0: my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; michael@0: register int pixcode; michael@0: register JSAMPROW input_ptr; michael@0: register JSAMPROW output_ptr; michael@0: JSAMPROW colorindex0 = cquantize->colorindex[0]; michael@0: JSAMPROW colorindex1 = cquantize->colorindex[1]; michael@0: JSAMPROW colorindex2 = cquantize->colorindex[2]; michael@0: int * dither0; /* points to active row of dither matrix */ michael@0: int * dither1; michael@0: int * dither2; michael@0: int row_index, col_index; /* current indexes into dither matrix */ michael@0: int row; michael@0: JDIMENSION col; michael@0: JDIMENSION width = cinfo->output_width; michael@0: michael@0: for (row = 0; row < num_rows; row++) { michael@0: row_index = cquantize->row_index; michael@0: input_ptr = input_buf[row]; michael@0: output_ptr = output_buf[row]; michael@0: dither0 = cquantize->odither[0][row_index]; michael@0: dither1 = cquantize->odither[1][row_index]; michael@0: dither2 = cquantize->odither[2][row_index]; michael@0: col_index = 0; michael@0: michael@0: for (col = width; col > 0; col--) { michael@0: pixcode = GETJSAMPLE(colorindex0[GETJSAMPLE(*input_ptr++) + michael@0: dither0[col_index]]); michael@0: pixcode += GETJSAMPLE(colorindex1[GETJSAMPLE(*input_ptr++) + michael@0: dither1[col_index]]); michael@0: pixcode += GETJSAMPLE(colorindex2[GETJSAMPLE(*input_ptr++) + michael@0: dither2[col_index]]); michael@0: *output_ptr++ = (JSAMPLE) pixcode; michael@0: col_index = (col_index + 1) & ODITHER_MASK; michael@0: } michael@0: row_index = (row_index + 1) & ODITHER_MASK; michael@0: cquantize->row_index = row_index; michael@0: } michael@0: } michael@0: michael@0: michael@0: METHODDEF(void) michael@0: quantize_fs_dither (j_decompress_ptr cinfo, JSAMPARRAY input_buf, michael@0: JSAMPARRAY output_buf, int num_rows) michael@0: /* General case, with Floyd-Steinberg dithering */ michael@0: { michael@0: my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; michael@0: register LOCFSERROR cur; /* current error or pixel value */ michael@0: LOCFSERROR belowerr; /* error for pixel below cur */ michael@0: LOCFSERROR bpreverr; /* error for below/prev col */ michael@0: LOCFSERROR bnexterr; /* error for below/next col */ michael@0: LOCFSERROR delta; michael@0: register FSERRPTR errorptr; /* => fserrors[] at column before current */ michael@0: register JSAMPROW input_ptr; michael@0: register JSAMPROW output_ptr; michael@0: JSAMPROW colorindex_ci; michael@0: JSAMPROW colormap_ci; michael@0: int pixcode; michael@0: int nc = cinfo->out_color_components; michael@0: int dir; /* 1 for left-to-right, -1 for right-to-left */ michael@0: int dirnc; /* dir * nc */ michael@0: int ci; michael@0: int row; michael@0: JDIMENSION col; michael@0: JDIMENSION width = cinfo->output_width; michael@0: JSAMPLE *range_limit = cinfo->sample_range_limit; michael@0: SHIFT_TEMPS michael@0: michael@0: for (row = 0; row < num_rows; row++) { michael@0: /* Initialize output values to 0 so can process components separately */ michael@0: jzero_far((void FAR *) output_buf[row], michael@0: (size_t) (width * SIZEOF(JSAMPLE))); michael@0: for (ci = 0; ci < nc; ci++) { michael@0: input_ptr = input_buf[row] + ci; michael@0: output_ptr = output_buf[row]; michael@0: if (cquantize->on_odd_row) { michael@0: /* work right to left in this row */ michael@0: input_ptr += (width-1) * nc; /* so point to rightmost pixel */ michael@0: output_ptr += width-1; michael@0: dir = -1; michael@0: dirnc = -nc; michael@0: errorptr = cquantize->fserrors[ci] + (width+1); /* => entry after last column */ michael@0: } else { michael@0: /* work left to right in this row */ michael@0: dir = 1; michael@0: dirnc = nc; michael@0: errorptr = cquantize->fserrors[ci]; /* => entry before first column */ michael@0: } michael@0: colorindex_ci = cquantize->colorindex[ci]; michael@0: colormap_ci = cquantize->sv_colormap[ci]; michael@0: /* Preset error values: no error propagated to first pixel from left */ michael@0: cur = 0; michael@0: /* and no error propagated to row below yet */ michael@0: belowerr = bpreverr = 0; michael@0: michael@0: for (col = width; col > 0; col--) { michael@0: /* cur holds the error propagated from the previous pixel on the michael@0: * current line. Add the error propagated from the previous line michael@0: * to form the complete error correction term for this pixel, and michael@0: * round the error term (which is expressed * 16) to an integer. michael@0: * RIGHT_SHIFT rounds towards minus infinity, so adding 8 is correct michael@0: * for either sign of the error value. michael@0: * Note: errorptr points to *previous* column's array entry. michael@0: */ michael@0: cur = RIGHT_SHIFT(cur + errorptr[dir] + 8, 4); michael@0: /* Form pixel value + error, and range-limit to 0..MAXJSAMPLE. michael@0: * The maximum error is +- MAXJSAMPLE; this sets the required size michael@0: * of the range_limit array. michael@0: */ michael@0: cur += GETJSAMPLE(*input_ptr); michael@0: cur = GETJSAMPLE(range_limit[cur]); michael@0: /* Select output value, accumulate into output code for this pixel */ michael@0: pixcode = GETJSAMPLE(colorindex_ci[cur]); michael@0: *output_ptr += (JSAMPLE) pixcode; michael@0: /* Compute actual representation error at this pixel */ michael@0: /* Note: we can do this even though we don't have the final */ michael@0: /* pixel code, because the colormap is orthogonal. */ michael@0: cur -= GETJSAMPLE(colormap_ci[pixcode]); michael@0: /* Compute error fractions to be propagated to adjacent pixels. michael@0: * Add these into the running sums, and simultaneously shift the michael@0: * next-line error sums left by 1 column. michael@0: */ michael@0: bnexterr = cur; michael@0: delta = cur * 2; michael@0: cur += delta; /* form error * 3 */ michael@0: errorptr[0] = (FSERROR) (bpreverr + cur); michael@0: cur += delta; /* form error * 5 */ michael@0: bpreverr = belowerr + cur; michael@0: belowerr = bnexterr; michael@0: cur += delta; /* form error * 7 */ michael@0: /* At this point cur contains the 7/16 error value to be propagated michael@0: * to the next pixel on the current line, and all the errors for the michael@0: * next line have been shifted over. We are therefore ready to move on. michael@0: */ michael@0: input_ptr += dirnc; /* advance input ptr to next column */ michael@0: output_ptr += dir; /* advance output ptr to next column */ michael@0: errorptr += dir; /* advance errorptr to current column */ michael@0: } michael@0: /* Post-loop cleanup: we must unload the final error value into the michael@0: * final fserrors[] entry. Note we need not unload belowerr because michael@0: * it is for the dummy column before or after the actual array. michael@0: */ michael@0: errorptr[0] = (FSERROR) bpreverr; /* unload prev err into array */ michael@0: } michael@0: cquantize->on_odd_row = (cquantize->on_odd_row ? FALSE : TRUE); michael@0: } michael@0: } michael@0: michael@0: michael@0: /* michael@0: * Allocate workspace for Floyd-Steinberg errors. michael@0: */ michael@0: michael@0: LOCAL(void) michael@0: alloc_fs_workspace (j_decompress_ptr cinfo) michael@0: { michael@0: my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; michael@0: size_t arraysize; michael@0: int i; michael@0: michael@0: arraysize = (size_t) ((cinfo->output_width + 2) * SIZEOF(FSERROR)); michael@0: for (i = 0; i < cinfo->out_color_components; i++) { michael@0: cquantize->fserrors[i] = (FSERRPTR) michael@0: (*cinfo->mem->alloc_large)((j_common_ptr) cinfo, JPOOL_IMAGE, arraysize); michael@0: } michael@0: } michael@0: michael@0: michael@0: /* michael@0: * Initialize for one-pass color quantization. michael@0: */ michael@0: michael@0: METHODDEF(void) michael@0: start_pass_1_quant (j_decompress_ptr cinfo, boolean is_pre_scan) michael@0: { michael@0: my_cquantize_ptr cquantize = (my_cquantize_ptr) cinfo->cquantize; michael@0: size_t arraysize; michael@0: int i; michael@0: michael@0: /* Install my colormap. */ michael@0: cinfo->colormap = cquantize->sv_colormap; michael@0: cinfo->actual_number_of_colors = cquantize->sv_actual; michael@0: michael@0: /* Initialize for desired dithering mode. */ michael@0: switch (cinfo->dither_mode) { michael@0: case JDITHER_NONE: michael@0: if (cinfo->out_color_components == 3) michael@0: cquantize->pub.color_quantize = color_quantize3; michael@0: else michael@0: cquantize->pub.color_quantize = color_quantize; michael@0: break; michael@0: case JDITHER_ORDERED: michael@0: if (cinfo->out_color_components == 3) michael@0: cquantize->pub.color_quantize = quantize3_ord_dither; michael@0: else michael@0: cquantize->pub.color_quantize = quantize_ord_dither; michael@0: cquantize->row_index = 0; /* initialize state for ordered dither */ michael@0: /* If user changed to ordered dither from another mode, michael@0: * we must recreate the color index table with padding. michael@0: * This will cost extra space, but probably isn't very likely. michael@0: */ michael@0: if (! cquantize->is_padded) michael@0: create_colorindex(cinfo); michael@0: /* Create ordered-dither tables if we didn't already. */ michael@0: if (cquantize->odither[0] == NULL) michael@0: create_odither_tables(cinfo); michael@0: break; michael@0: case JDITHER_FS: michael@0: cquantize->pub.color_quantize = quantize_fs_dither; michael@0: cquantize->on_odd_row = FALSE; /* initialize state for F-S dither */ michael@0: /* Allocate Floyd-Steinberg workspace if didn't already. */ michael@0: if (cquantize->fserrors[0] == NULL) michael@0: alloc_fs_workspace(cinfo); michael@0: /* Initialize the propagated errors to zero. */ michael@0: arraysize = (size_t) ((cinfo->output_width + 2) * SIZEOF(FSERROR)); michael@0: for (i = 0; i < cinfo->out_color_components; i++) michael@0: jzero_far((void FAR *) cquantize->fserrors[i], arraysize); michael@0: break; michael@0: default: michael@0: ERREXIT(cinfo, JERR_NOT_COMPILED); michael@0: break; michael@0: } michael@0: } michael@0: michael@0: michael@0: /* michael@0: * Finish up at the end of the pass. michael@0: */ michael@0: michael@0: METHODDEF(void) michael@0: finish_pass_1_quant (j_decompress_ptr cinfo) michael@0: { michael@0: /* no work in 1-pass case */ michael@0: } michael@0: michael@0: michael@0: /* michael@0: * Switch to a new external colormap between output passes. michael@0: * Shouldn't get to this module! michael@0: */ michael@0: michael@0: METHODDEF(void) michael@0: new_color_map_1_quant (j_decompress_ptr cinfo) michael@0: { michael@0: ERREXIT(cinfo, JERR_MODE_CHANGE); michael@0: } michael@0: michael@0: michael@0: /* michael@0: * Module initialization routine for 1-pass color quantization. michael@0: */ michael@0: michael@0: GLOBAL(void) michael@0: jinit_1pass_quantizer (j_decompress_ptr cinfo) michael@0: { michael@0: my_cquantize_ptr cquantize; michael@0: michael@0: cquantize = (my_cquantize_ptr) michael@0: (*cinfo->mem->alloc_small) ((j_common_ptr) cinfo, JPOOL_IMAGE, michael@0: SIZEOF(my_cquantizer)); michael@0: cinfo->cquantize = (struct jpeg_color_quantizer *) cquantize; michael@0: cquantize->pub.start_pass = start_pass_1_quant; michael@0: cquantize->pub.finish_pass = finish_pass_1_quant; michael@0: cquantize->pub.new_color_map = new_color_map_1_quant; michael@0: cquantize->fserrors[0] = NULL; /* Flag FS workspace not allocated */ michael@0: cquantize->odither[0] = NULL; /* Also flag odither arrays not allocated */ michael@0: michael@0: /* Make sure my internal arrays won't overflow */ michael@0: if (cinfo->out_color_components > MAX_Q_COMPS) michael@0: ERREXIT1(cinfo, JERR_QUANT_COMPONENTS, MAX_Q_COMPS); michael@0: /* Make sure colormap indexes can be represented by JSAMPLEs */ michael@0: if (cinfo->desired_number_of_colors > (MAXJSAMPLE+1)) michael@0: ERREXIT1(cinfo, JERR_QUANT_MANY_COLORS, MAXJSAMPLE+1); michael@0: michael@0: /* Create the colormap and color index table. */ michael@0: create_colormap(cinfo); michael@0: create_colorindex(cinfo); michael@0: michael@0: /* Allocate Floyd-Steinberg workspace now if requested. michael@0: * We do this now since it is FAR storage and may affect the memory michael@0: * manager's space calculations. If the user changes to FS dither michael@0: * mode in a later pass, we will allocate the space then, and will michael@0: * possibly overrun the max_memory_to_use setting. michael@0: */ michael@0: if (cinfo->dither_mode == JDITHER_FS) michael@0: alloc_fs_workspace(cinfo); michael@0: } michael@0: michael@0: #endif /* QUANT_1PASS_SUPPORTED */