/* * libpipi Pathetic image processing interface library * Copyright (c) 2004-2008 Sam Hocevar * All Rights Reserved * * $Id$ * * This library is free software. It comes without any warranty, to * the extent permitted by applicable law. You can redistribute it * and/or modify it under the terms of the Do What The Fuck You Want * To Public License, Version 2, as published by Sam Hocevar. See * http://sam.zoy.org/wtfpl/COPYING for more details. */ /* * oric.c: Oric Atmos import/export functions */ #include "config.h" #include #include #include #include #include "pipi.h" #include "pipi_internals.h" /* Image dimensions and recursion depth. DEPTH = 2 is a reasonable value, * DEPTH = 3 gives good quality, and higher values may improve the results * even more but at the cost of significantly longer computation times. */ #define WIDTH 240 #define HEIGHT 200 #define DEPTH 2 static int read_screen(char const *name, uint8_t *screen); static void write_screen(float const *data, uint8_t *screen); pipi_image_t *pipi_load_oric(char const *name) { static uint8_t const pal[32] = { 0x00, 0x00, 0x00, 0xff, 0x00, 0x00, 0xff, 0xff, 0x00, 0xff, 0x00, 0xff, 0x00, 0xff, 0xff, 0xff, 0xff, 0x00, 0x00, 0xff, 0xff, 0x00, 0xff, 0xff, 0xff, 0xff, 0x00, 0xff, 0xff, 0xff, 0xff, 0xff, }; pipi_image_t *img; pipi_pixels_t *p; uint8_t *screen, *data; int x, y, i; screen = malloc(WIDTH * HEIGHT / 6); if(read_screen(name, screen) < 0) { free(screen); return NULL; } img = pipi_new(WIDTH, HEIGHT); p = pipi_get_pixels(img, PIPI_PIXELS_RGBA_C); data = p->pixels; for(y = 0; y < HEIGHT; y++) { int bg = 0, fg = 7; for(x = 0; x < 40; x++) { int col; uint8_t c = screen[y * 40 + x]; if(c & 0x40) { for(i = 0; i < 6; i++) { col = (c & (1 << (5 - i))) ? (c & 0x80) ? 7 - fg : fg : (c & 0x80) ? 7 - bg : bg; memcpy(data + (y * WIDTH + x * 6 + i) * 4, pal + 4 * col, 4); } } else if((c & 0x60) == 0x00) { if(c & 0x10) bg = c & 0x7; else fg = c & 0x7; col = (c & 0x80) ? 7 - bg : bg; for(i = 0; i < 6; i++) memcpy(data + (y * WIDTH + x * 6 + i) * 4, pal + 4 * col, 4); } /* else: invalid sequence */ } } free(screen); img->codec_priv = NULL; img->wrap = 0; img->u8 = 1; pipi_release_pixels(img, p); return img; } int pipi_save_oric(pipi_image_t *img, char const *name) { pipi_image_t *tmp = NULL; pipi_pixels_t *p; float *data; uint8_t *screen; FILE *fp; size_t len; len = strlen(name); if(len < 4 || name[len - 4] != '.' || toupper(name[len - 3]) != 'T' || toupper(name[len - 2]) != 'A' || toupper(name[len - 1]) != 'P') return -1; fp = fopen(name, "w"); if(!fp) return -1; fwrite("\x16\x16\x16\x16\x24", 1, 5, fp); fwrite("\x00\xff\x80\x00\xbf\x3f\xa0\x00\x00", 1, 9, fp); fwrite(name, 1, len - 4, fp); fwrite("\x00", 1, 1, fp); if(img->w != WIDTH || img->h != HEIGHT) tmp = pipi_resize(img, WIDTH, HEIGHT); else tmp = img; p = pipi_get_pixels(tmp, PIPI_PIXELS_RGBA_F); data = p->pixels; screen = malloc(WIDTH * HEIGHT / 6); write_screen(data, screen); pipi_release_pixels(tmp, p); if(tmp != img) pipi_free(tmp); fwrite(screen, 1, WIDTH * HEIGHT / 6, fp); fclose(fp); free(screen); return 0; } /* * XXX: The following functions are local. */ static int read_screen(char const *name, uint8_t *screen) { FILE *fp; int ch; fp = fopen(name, "r"); if(!fp) return -1; /* Skip the sync bytes */ ch = fgetc(fp); if(ch != 0x16) goto syntax_error; while((ch = fgetc(fp)) == 0x16) ; if(ch != 0x24) goto syntax_error; /* Skip the header, ignoring the last byte’s value */ if(fgetc(fp) != 0x00 || fgetc(fp) != 0xff || fgetc(fp) != 0x80 || fgetc(fp) != 0x00 || fgetc(fp) != 0xbf || fgetc(fp) != 0x3f || fgetc(fp) != 0xa0 || fgetc(fp) != 0x00 || fgetc(fp) == EOF) goto syntax_error; /* Skip the file name, including trailing nul char */ for(;;) { ch = fgetc(fp); if(ch == EOF) goto syntax_error; if(ch == 0x00) break; } /* Read screen data */ if(fread(screen, 1, WIDTH * HEIGHT / 6, fp) != WIDTH * HEIGHT / 6) goto syntax_error; fclose(fp); return 0; syntax_error: fclose(fp); return -1; } /* Error diffusion table, similar to Floyd-Steinberg. I choose not to * propagate 100% of the error, because doing so creates awful artifacts * (full lines of the same colour, massive colour bleeding) for unclear * reasons. Atkinson dithering propagates 3/4 of the error, which is even * less than our 31/32. I also choose to propagate slightly more in the * X direction to avoid banding effects due to rounding errors. * It would be interesting, for future versions of this software, to * propagate the error to the second line, too. But right now I find it far * too complex to do. * * +-------+-------+ * | error |FS0/FSX| * +-------+-------+-------+ * |FS1/FSX|FS2/FSX|FS3/FSX| * +-------+-------+-------+ */ #define FS0 15 #define FS1 6 #define FS2 9 #define FS3 1 #define FSX 32 /* The simple Oric RGB palette, made of the 8 Neugebauer primary colours. Each * colour is repeated 6 times so that we can point to the palette to paste * whole blocks of 6 pixels. It’s also organised so that palette[7-x] is the * RGB negative of palette[x], and screen command X uses palette[X & 7]. */ #define o 0x0000 #define X 0xffff static const int palette[8][6 * 3] = { { o, o, o, o, o, o, o, o, o, o, o, o, o, o, o, o, o, o }, { X, o, o, X, o, o, X, o, o, X, o, o, X, o, o, X, o, o }, { o, X, o, o, X, o, o, X, o, o, X, o, o, X, o, o, X, o }, { X, X, o, X, X, o, X, X, o, X, X, o, X, X, o, X, X, o }, { o, o, X, o, o, X, o, o, X, o, o, X, o, o, X, o, o, X }, { X, o, X, X, o, X, X, o, X, X, o, X, X, o, X, X, o, X }, { o, X, X, o, X, X, o, X, X, o, X, X, o, X, X, o, X, X }, { X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X, X }, }; /* Set new background and foreground colours according to the given command. */ static inline void domove(uint8_t command, uint8_t *bg, uint8_t *fg) { if((command & 0x78) == 0x00) *fg = command & 0x7; else if((command & 0x78) == 0x10) *bg = command & 0x7; } /* Clamp pixel value to avoid colour bleeding. Deactivated because it * does not give satisfactory results. */ #define CLAMP 0x1000 static inline int clamp(int p) { #if 0 /* FIXME: doesn’t give terribly good results on eg. eatme.png */ if(p < - CLAMP) return - CLAMP; if(p > 0xffff + CLAMP) return 0xffff + CLAMP; #endif return p; } /* Compute the perceptual error caused by replacing the input pixels "in" * with the output pixels "out". "inerr" is the diffused error that should * be applied to "in"’s first pixel. "outerr" will hold the diffused error * to apply after "in"’s last pixel upon next call. The return value does * not mean much physically; it is one part of the algorithm where you need * to play a bit in order to get appealing results. That’s how image * processing works, dude. */ static inline int geterror(int const *in, int const *inerr, int const *out, int *outerr) { int tmperr[9 * 3]; int i, c, ret = 0; /* 9 cells: 1 for the end of line, 8 for the errors below */ memcpy(tmperr, inerr, 3 * sizeof(int)); memset(tmperr + 3, 0, 8 * 3 * sizeof(int)); for(i = 0; i < 6; i++) { for(c = 0; c < 3; c++) { /* Experiment shows that this is important at small depths */ int a = clamp(in[i * 3 + c] + tmperr[c]); int b = out[i * 3 + c]; tmperr[c] = (a - b) * FS0 / FSX; tmperr[c + (i * 3 + 3)] += (a - b) * FS1 / FSX; tmperr[c + (i * 3 + 6)] += (a - b) * FS2 / FSX; tmperr[c + (i * 3 + 9)] += (a - b) * FS3 / FSX; ret += (a - b) / 256 * (a - b) / 256; } } for(i = 0; i < 4; i++) { for(c = 0; c < 3; c++) { /* Experiment shows that this is important at large depths */ int a = ((in[i * 3 + c] + in[i * 3 + 3 + c] + in[i * 3 + 6 + c]) / 3); int b = ((out[i * 3 + c] + out[i * 3 + 3 + c] + out[i * 3 + 6 + c]) / 3); ret += (a - b) / 256 * (a - b) / 256; } } /* Using the diffused error as a perceptual error component is stupid, * because that’s not what it is at all, but I found that it helped a * bit in some cases. */ for(i = 0; i < 3; i++) ret += tmperr[i] / 256 * tmperr[i] / 256; memcpy(outerr, tmperr, 3 * sizeof(int)); return ret; } static uint8_t bestmove(int const *in, uint8_t bg, uint8_t fg, int const *errvec, int depth, int maxerror, int *error, int *out) { int voidvec[3], nvoidvec[3], bestrgb[6 * 3], tmprgb[6 * 3], tmpvec[3]; int const *voidrgb, *nvoidrgb, *vec, *rgb; int besterror, curerror, suberror, statice, voide, nvoide; int i, j, c; uint8_t command, bestcommand; /* Precompute error for the case where we change the foreground colour * and hence only print the background colour or its negative */ voidrgb = palette[bg]; voide = geterror(in, errvec, voidrgb, voidvec); nvoidrgb = palette[7 - bg]; nvoide = geterror(in, errvec, nvoidrgb, nvoidvec); /* Precompute sub-error for the case where we print pixels (and hence * don’t change the palette). It’s not the exact error because we should * be propagating the error to the first pixel here. */ if(depth > 0) { int tmp[3] = { 0, 0, 0 }; bestmove(in + 6 * 3, bg, fg, tmp, depth - 1, maxerror, &statice, NULL); } /* Check every likely command: * 0-7: change foreground to 0-7 * 8-15: change foreground to 0-7, print negative background * 16-23: change background to 0-7 * 24-31: change background to 0-7, print negative background * 32: normal stuff * 33: inverse video stuff */ besterror = 0x7ffffff; bestcommand = 0x10; memcpy(bestrgb, voidrgb, 6 * 3 * sizeof(int)); for(j = 0; j < 34; j++) { static uint8_t const lookup[] = { 0x00, 0x04, 0x01, 0x05, 0x02, 0x06, 0x03, 0x07, 0x80, 0x84, 0x81, 0x85, 0x82, 0x86, 0x83, 0x87, 0x10, 0x14, 0x11, 0x15, 0x12, 0x16, 0x13, 0x17, 0x90, 0x94, 0x91, 0x95, 0x92, 0x96, 0x93, 0x97, 0x40, 0xc0 }; uint8_t newbg = bg, newfg = fg; command = lookup[j]; domove(command, &newbg, &newfg); /* Keeping bg and fg is useless, because we could use standard * pixel printing instead */ if((command & 0x40) == 0x00 && newbg == bg && newfg == fg) continue; /* I *think* having newfg == newbg is useless, too, but I don’t * want to miss some corner case where swapping bg and fg may be * interesting, so we continue anyway. */ #if 0 /* Bit 6 off and bit 5 on seems illegal */ if((command & 0x60) == 0x20) continue; /* Bits 6 and 5 off and bit 3 on seems illegal */ if((command & 0x68) == 0x08) continue; #endif if((command & 0xf8) == 0x00) { curerror = voide; rgb = voidrgb; vec = voidvec; } else if((command & 0xf8) == 0x80) { curerror = nvoide; rgb = nvoidrgb; vec = nvoidvec; } else if((command & 0xf8) == 0x10) { rgb = palette[newbg]; curerror = geterror(in, errvec, rgb, tmpvec); vec = tmpvec; } else if((command & 0xf8) == 0x90) { rgb = palette[7 - newbg]; curerror = geterror(in, errvec, rgb, tmpvec); vec = tmpvec; } else { int const *bgcolor, *fgcolor; if((command & 0x80) == 0x00) { bgcolor = palette[bg]; fgcolor = palette[fg]; } else { bgcolor = palette[7 - bg]; fgcolor = palette[7 - fg]; } memcpy(tmpvec, errvec, 3 * sizeof(int)); curerror = 0; for(i = 0; i < 6; i++) { int vec1[3], vec2[3]; int smalle1 = 0, smalle2 = 0; memcpy(vec1, tmpvec, 3 * sizeof(int)); memcpy(vec2, tmpvec, 3 * sizeof(int)); for(c = 0; c < 3; c++) { int delta1, delta2; delta1 = clamp(in[i * 3 + c] + tmpvec[c]) - bgcolor[c]; vec1[c] = delta1 * FS0 / FSX; smalle1 += delta1 / 256 * delta1; delta2 = clamp(in[i * 3 + c] + tmpvec[c]) - fgcolor[c]; vec2[c] = delta2 * FS0 / FSX; smalle2 += delta2 / 256 * delta2; } if(smalle1 < smalle2) { memcpy(tmpvec, vec1, 3 * sizeof(int)); memcpy(tmprgb + i * 3, bgcolor, 3 * sizeof(int)); } else { memcpy(tmpvec, vec2, 3 * sizeof(int)); memcpy(tmprgb + i * 3, fgcolor, 3 * sizeof(int)); command |= (1 << (5 - i)); } } /* Recompute full error */ curerror += geterror(in, errvec, tmprgb, tmpvec); rgb = tmprgb; vec = tmpvec; } if(curerror > besterror) continue; /* Try to avoid bad decisions now that will have a high cost * later in the line by making the next error more important than * the current error. */ curerror = curerror * 3 / 4; if(depth == 0) suberror = 0; /* It’s the end of the tree */ else if((command & 0x68) == 0x00) { bestmove(in + 6 * 3, newbg, newfg, vec, depth - 1, besterror - curerror, &suberror, NULL); #if 0 /* Slight penalty for colour changes; they're hard to revert. The * value of 2 was determined empirically. 1.5 is not enough and * 3 is too much. */ if(newbg != bg) suberror = suberror * 10 / 8; else if(newfg != fg) suberror = suberror * 9 / 8; #endif } else suberror = statice; if(curerror + suberror < besterror) { besterror = curerror + suberror; bestcommand = command; memcpy(bestrgb, rgb, 6 * 3 * sizeof(int)); } } *error = besterror; if(out) memcpy(out, bestrgb, 6 * 3 * sizeof(int)); return bestcommand; } static void write_screen(float const *data, uint8_t *screen) { int *src, *srcl, *dst, *dstl; int stride, x, y, depth, c; stride = (WIDTH + 1) * 3; src = malloc((WIDTH + 1) * (HEIGHT + 1) * 3 * sizeof(int)); memset(src, 0, (WIDTH + 1) * (HEIGHT + 1) * 3 * sizeof(int)); dst = malloc((WIDTH + 1) * (HEIGHT + 1) * 3 * sizeof(int)); memset(dst, 0, (WIDTH + 1) * (HEIGHT + 1) * 3 * sizeof(int)); /* Import pixels into our custom format */ for(y = 0; y < HEIGHT; y++) for(x = 0; x < WIDTH; x++) for(c = 0; c < 3; c++) src[y * stride + x * 3 + c] = 0xffff * data[(y * WIDTH + x) * 4 + (2 - c)]; /* Let the fun begin */ for(y = 0; y < HEIGHT; y++) { uint8_t bg = 0, fg = 7; //fprintf(stderr, "\rProcessing... %i%%", (y * 100 + 99) / HEIGHT); for(x = 0; x < WIDTH; x += 6) { int errvec[3] = { 0, 0, 0 }; int dummy, i; uint8_t command; depth = (x + DEPTH < WIDTH) ? DEPTH : (WIDTH - x) / 6 - 1; srcl = src + y * stride + x * 3; dstl = dst + y * stride + x * 3; /* Recursively compute and apply best command */ command = bestmove(srcl, bg, fg, errvec, depth, 0x7fffff, &dummy, dstl); /* Propagate error */ for(c = 0; c < 3; c++) { for(i = 0; i < 6; i++) { int error = srcl[i * 3 + c] - dstl[i * 3 + c]; srcl[i * 3 + c + 3] = clamp(srcl[i * 3 + c + 3] + error * FS0 / FSX); srcl[i * 3 + c + stride - 3] += error * FS1 / FSX; srcl[i * 3 + c + stride] += error * FS2 / FSX; srcl[i * 3 + c + stride + 3] += error * FS3 / FSX; } for(i = -1; i < 7; i++) srcl[i * 3 + c + stride] = clamp(srcl[i * 3 + c + stride]); } /* Iterate */ domove(command, &bg, &fg); /* Write byte to file */ screen[y * (WIDTH / 6) + (x / 6)] = command; } } //fprintf(stderr, " done.\n"); }