/* ** Copyright (C) 1995,1998 by Alexander Lehmann ** and Willem van Schaik ** ** Permission to use, copy, modify, and distribute this software and its ** documentation for any purpose and without fee is hereby granted, provided ** that the above copyright notice appear in all copies and that both that ** copyright notice and this permission notice appear in supporting ** documentation. This software is provided "as is" without express or ** implied warranty. ** ** modeled after giftopnm by David Koblas and ** with lots of bits pasted from libpng.txt by Guy Eric Schalnat */ #ifndef PNMTOPNG_WARNING_LEVEL # define PNMTOPNG_WARNING_LEVEL 0 /* use 0 for backward compatibility, */ #endif /* 2 for warnings (1 == error) */ #include #include #include #include /* includes zlib.h and setjmp.h */ #define VERSION "2.37.4 (5 December 1999) +netpbm" #include "pm_c_util.h" #include "mallocvar.h" #include "nstring.h" #include "shhopt.h" #include "pam.h" /* A hack until we can remove direct access to png_info from the program */ #if PNG_LIBPNG_VER >= 10400 #define trans_values trans_color #define TRANS_ALPHA trans_alpha #else #define TRANS_ALPHA trans #endif typedef struct _jmpbuf_wrapper { jmp_buf jmpbuf; } jmpbuf_wrapper; enum alpha_handling {ALPHA_NONE, ALPHA_ONLY, ALPHA_MIX, ALPHA_IN}; struct cmdlineInfo { /* All the information the user supplied in the command line, in a form easy for the program to use. */ const char *inputFilespec; /* '-' if stdin */ unsigned int verbose; enum alpha_handling alpha; const char * background; float gamma; /* -1.0 means unspecified */ const char * text; unsigned int time; }; typedef struct { /*---------------------------------------------------------------------------- A color in a format compatible with the PNG library. Note that the PNG library declares types png_color and png_color_16 which are similar. -----------------------------------------------------------------------------*/ png_uint_16 r; png_uint_16 g; png_uint_16 b; } pngcolor; static png_uint_16 maxval; static bool verbose; static jmpbuf_wrapper pngtopnm_jmpbuf_struct; static void parseCommandLine(int argc, const char ** argv, struct cmdlineInfo * cmdlineP ) { /*---------------------------------------------------------------------------- Parse program command line described in Unix standard form by argc and argv. Return the information in the options as *cmdlineP. If command line is internally inconsistent (invalid options, etc.), issue error message to stderr and abort program. Note that the strings we return are stored in the storage that was passed to us as the argv array. We also trash *argv. -----------------------------------------------------------------------------*/ optEntry * option_def; /* Instructions to optParseOptions3 on how to parse our options. */ optStruct3 opt; unsigned int option_def_index; unsigned int alphaSpec, alphapamSpec, mixSpec, backgroundSpec, gammaSpec, textSpec; MALLOCARRAY(option_def, 100); option_def_index = 0; /* incremented by OPTENT3 */ OPTENT3(0, "verbose", OPT_FLAG, NULL, &cmdlineP->verbose, 0); OPTENT3(0, "alpha", OPT_FLAG, NULL, &alphaSpec, 0); OPTENT3(0, "alphapam", OPT_FLAG, NULL, &alphapamSpec, 0); OPTENT3(0, "mix", OPT_FLAG, NULL, &mixSpec, 0); OPTENT3(0, "background", OPT_STRING, &cmdlineP->background, &backgroundSpec, 0); OPTENT3(0, "gamma", OPT_FLOAT, &cmdlineP->gamma, &gammaSpec, 0); OPTENT3(0, "text", OPT_STRING, &cmdlineP->text, &textSpec, 0); OPTENT3(0, "time", OPT_FLAG, NULL, &cmdlineP->time, 0); opt.opt_table = option_def; opt.short_allowed = FALSE; /* We have no short (old-fashioned) options */ opt.allowNegNum = FALSE; /* We have no parms that are negative numbers */ optParseOptions3(&argc, (char **)argv, opt, sizeof(opt), 0); /* Uses and sets argc, argv, and some of *cmdlineP and others. */ if (alphaSpec + mixSpec + alphapamSpec > 1) pm_error("You cannot specify more than one of -alpha -alphapam -mix"); else if (alphaSpec) cmdlineP->alpha = ALPHA_ONLY; else if (mixSpec) cmdlineP->alpha = ALPHA_MIX; else if (alphapamSpec) cmdlineP->alpha = ALPHA_IN; else cmdlineP->alpha = ALPHA_NONE; if (backgroundSpec && !mixSpec) pm_error("-background is useless without -mix"); if (!backgroundSpec) cmdlineP->background = NULL; if (!gammaSpec) cmdlineP->gamma = -1.0; if (!textSpec) cmdlineP->text = NULL; if (argc-1 < 1) cmdlineP->inputFilespec = "-"; else if (argc-1 == 1) cmdlineP->inputFilespec = argv[1]; else pm_error("Program takes at most one argument: input file name. " "you specified %d", argc-1); } static png_uint_16 get_png_val(const png_byte ** const pp, int const bit_depth) { png_uint_16 c; if (bit_depth == 16) c = (*((*pp)++)) << 8; else c = 0; c |= (*((*pp)++)); return c; } static bool isGrayscale(pngcolor const color) { return color.r == color.g && color.r == color.b; } static sample alphaMix(png_uint_16 const foreground, png_uint_16 const background, png_uint_16 const alpha, sample const maxval) { double const opacity = (double)alpha / maxval; double const transparency = 1.0 - opacity; return ROUNDU(foreground * opacity + background * transparency); } static void setTuple(const struct pam * const pamP, tuple const tuple, pngcolor const foreground, pngcolor const background, enum alpha_handling const alphaHandling, png_uint_16 const alpha) { if (alphaHandling == ALPHA_ONLY) tuple[0] = alpha; else if (alphaHandling == ALPHA_NONE || (alphaHandling == ALPHA_MIX && alpha == maxval)) { if (pamP->depth < 3) tuple[0] = foreground.r; else { tuple[PAM_RED_PLANE] = foreground.r; tuple[PAM_GRN_PLANE] = foreground.g; tuple[PAM_BLU_PLANE] = foreground.b; } } else if (alphaHandling == ALPHA_IN) { if (pamP->depth < 4) { tuple[0] = foreground.r; tuple[PAM_GRAY_TRN_PLANE] = alpha; } else { tuple[PAM_RED_PLANE] = foreground.r; tuple[PAM_GRN_PLANE] = foreground.g; tuple[PAM_BLU_PLANE] = foreground.b; tuple[PAM_TRN_PLANE] = alpha; } } else { assert(alphaHandling == ALPHA_MIX); if (pamP->depth < 3) tuple[0] = alphaMix(foreground.r, background.r, alpha, maxval); else { tuple[PAM_RED_PLANE] = alphaMix(foreground.r, background.r, alpha, maxval); tuple[PAM_GRN_PLANE] = alphaMix(foreground.g, background.g, alpha, maxval); tuple[PAM_BLU_PLANE] = alphaMix(foreground.b, background.b, alpha, maxval); } } } static png_uint_16 gamma_correct(png_uint_16 const v, float const g) { if (g != -1.0) return (png_uint_16) ROUNDU(pow((double) v / maxval, (1.0 / g)) * maxval); else return v; } static int iscolor (png_color c) { return c.red != c.green || c.green != c.blue; } static void save_text (png_info *info_ptr, FILE *tfp) { int i, j, k; for (i = 0 ; i < info_ptr->num_text ; i++) { j = 0; while (info_ptr->text[i].key[j] != '\0' && info_ptr->text[i].key[j] != ' ') j++; if (info_ptr->text[i].key[j] != ' ') { fprintf (tfp, "%s", info_ptr->text[i].key); for (j = strlen (info_ptr->text[i].key) ; j < 15 ; j++) putc (' ', tfp); } else { fprintf (tfp, "\"%s\"", info_ptr->text[i].key); for (j = strlen (info_ptr->text[i].key) ; j < 13 ; j++) putc (' ', tfp); } putc (' ', tfp); /* at least one space between key and text */ for (j = 0 ; j < info_ptr->text[i].text_length ; j++) { putc (info_ptr->text[i].text[j], tfp); if (info_ptr->text[i].text[j] == '\n') for (k = 0 ; k < 16 ; k++) putc ((int)' ', tfp); } putc ((int)'\n', tfp); } } static void show_time (png_info *info_ptr) { static const char * const month[] = { "", "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December" }; if (info_ptr->valid & PNG_INFO_tIME) { if (info_ptr->mod_time.month < 1 || info_ptr->mod_time.month >= ARRAY_SIZE(month)) { pm_message("tIME chunk in PNG input is invalid; " "modification time of image is unknown. " "The month value, which should be in the range " "1-12, is %u", info_ptr->mod_time.month); } else pm_message ("modification time: %02d %s %d %02d:%02d:%02d", info_ptr->mod_time.day, month[info_ptr->mod_time.month], info_ptr->mod_time.year, info_ptr->mod_time.hour, info_ptr->mod_time.minute, info_ptr->mod_time.second); } } static void pngtopnm_error_handler (png_structp png_ptr, png_const_charp msg) { jmpbuf_wrapper *jmpbuf_ptr; /* this function, aside from the extra step of retrieving the "error * pointer" (below) and the fact that it exists within the application * rather than within libpng, is essentially identical to libpng's * default error handler. The second point is critical: since both * setjmp() and longjmp() are called from the same code, they are * guaranteed to have compatible notions of how big a jmp_buf is, * regardless of whether _BSD_SOURCE or anything else has (or has not) * been defined. */ pm_message("fatal libpng error: %s", msg); jmpbuf_ptr = png_get_error_ptr(png_ptr); if (jmpbuf_ptr == NULL) { /* we are completely hosed now */ pm_error("EXTREMELY fatal error: jmpbuf unrecoverable; terminating."); } longjmp(jmpbuf_ptr->jmpbuf, 1); } static void dump_png_info(png_info *info_ptr) { const char *type_string; const char *filter_string; switch (info_ptr->color_type) { case PNG_COLOR_TYPE_GRAY: type_string = "gray"; break; case PNG_COLOR_TYPE_GRAY_ALPHA: type_string = "gray+alpha"; break; case PNG_COLOR_TYPE_PALETTE: type_string = "palette"; break; case PNG_COLOR_TYPE_RGB: type_string = "truecolor"; break; case PNG_COLOR_TYPE_RGB_ALPHA: type_string = "truecolor+alpha"; break; } switch (info_ptr->filter_type) { case PNG_FILTER_TYPE_BASE: asprintfN(&filter_string, "base filter"); break; default: asprintfN(&filter_string, "unknown filter type %d", info_ptr->filter_type); } pm_message("reading a %ldw x %ldh image, %d bit%s", info_ptr->width, info_ptr->height, info_ptr->bit_depth, info_ptr->bit_depth > 1 ? "s" : ""); pm_message("%s, %s, %s", type_string, info_ptr->interlace_type ? "Adam7 interlaced" : "not interlaced", filter_string); pm_message("background {index, gray, red, green, blue} = " "{%d, %d, %d, %d, %d}", info_ptr->background.index, info_ptr->background.gray, info_ptr->background.red, info_ptr->background.green, info_ptr->background.blue); strfree(filter_string); if (info_ptr->valid & PNG_INFO_tRNS) pm_message("tRNS chunk (transparency): %u entries", info_ptr->num_trans); else pm_message("tRNS chunk (transparency): not present"); if (info_ptr->valid & PNG_INFO_gAMA) pm_message("gAMA chunk (image gamma): gamma = %4.2f", info_ptr->gamma); else pm_message("gAMA chunk (image gamma): not present"); if (info_ptr->valid & PNG_INFO_sBIT) pm_message("sBIT chunk: present"); else pm_message("sBIT chunk: not present"); if (info_ptr->valid & PNG_INFO_cHRM) pm_message("cHRM chunk: present"); else pm_message("cHRM chunk: not present"); if (info_ptr->valid & PNG_INFO_PLTE) pm_message("PLTE chunk: %d entries", info_ptr->num_palette); else pm_message("PLTE chunk: not present"); if (info_ptr->valid & PNG_INFO_bKGD) pm_message("bKGD chunk: present"); else pm_message("bKGD chunk: not present"); if (info_ptr->valid & PNG_INFO_hIST) pm_message("hIST chunk: present"); else pm_message("hIST chunk: not present"); if (info_ptr->valid & PNG_INFO_pHYs) pm_message("pHYs chunk: present"); else pm_message("pHYs chunk: not present"); if (info_ptr->valid & PNG_INFO_oFFs) pm_message("oFFs chunk: present"); else pm_message("oFFs chunk: not present"); if (info_ptr->valid & PNG_INFO_tIME) pm_message("tIME chunk: present"); else pm_message("tIME chunk: not present"); if (info_ptr->valid & PNG_INFO_pCAL) pm_message("pCAL chunk: present"); else pm_message("pCAL chunk: not present"); if (info_ptr->valid & PNG_INFO_sRGB) pm_message("sRGB chunk: present"); else pm_message("sRGB chunk: not present"); } static unsigned int computePngLineSize(png_info * const pngInfoP) { unsigned int const bytesPerSample = pngInfoP->bit_depth == 16 ? 2 : 1; unsigned int samplesPerPixel; switch (pngInfoP->color_type) { case PNG_COLOR_TYPE_GRAY_ALPHA: samplesPerPixel = 2; break; case PNG_COLOR_TYPE_RGB: samplesPerPixel = 3; break; case PNG_COLOR_TYPE_RGB_ALPHA: samplesPerPixel = 4; break; default: samplesPerPixel = 1; } if (UINT_MAX / bytesPerSample / samplesPerPixel < pngInfoP->width) pm_error("Width %u of PNG is uncomputably large", (unsigned int)pngInfoP->width); return pngInfoP->width * bytesPerSample * samplesPerPixel; } static void allocPngRaster(png_info * const pngInfoP, png_byte *** const pngImageP) { unsigned int const lineSize = computePngLineSize(pngInfoP); png_byte ** pngImage; unsigned int row; MALLOCARRAY(pngImage, pngInfoP->height); if (pngImage == NULL) pm_error("couldn't allocate space for %u PNG raster rows", (unsigned int)pngInfoP->height); for (row = 0; row < pngInfoP->height; ++row) { MALLOCARRAY(pngImage[row], lineSize); if (pngImage[row] == NULL) pm_error("couldn't allocate space for %uth row of PNG raster", row); } *pngImageP = pngImage; } static void freePngRaster(png_byte ** const pngRaster, png_info * const pngInfoP) { unsigned int row; for (row = 0; row < pngInfoP->height; ++row) free(pngRaster[row]); free(pngRaster); } static bool isTransparentColor(pngcolor const color, png_info * const pngInfoP, double const totalgamma) { /*---------------------------------------------------------------------------- Return TRUE iff pixels of color 'color' are supposed to be transparent everywhere they occur. Assume it's an RGB image. 'color' has been gamma-corrected. -----------------------------------------------------------------------------*/ bool retval; if (pngInfoP->valid & PNG_INFO_tRNS) { const png_color_16 * const transColorP = &pngInfoP->trans_values; /* It seems odd that libpng lets you get gamma-corrected pixel values, but not gamma-corrected transparency or background values. But as that is the case, we have to gamma-correct the transparency values. Note that because we compare the gamma-corrected values and there may be many-to-one mapping of uncorrected to corrected values, more pixels may be transparent than what the user intended. We could fix this by not letting libpng gamma-correct the pixels, and just do it ourselves. */ switch (pngInfoP->color_type) { case PNG_COLOR_TYPE_GRAY: retval = color.r == gamma_correct(transColorP->gray, totalgamma); break; default: retval = color.r == gamma_correct(transColorP->red, totalgamma) && color.g == gamma_correct(transColorP->green, totalgamma) && color.b == gamma_correct(transColorP->blue, totalgamma); } } else retval = FALSE; return retval; } #define SIG_CHECK_SIZE 4 static void read_sig_buf(FILE * const ifP) { unsigned char sig_buf[SIG_CHECK_SIZE]; size_t bytesRead; bytesRead = fread(sig_buf, 1, SIG_CHECK_SIZE, ifP); if (bytesRead != SIG_CHECK_SIZE) pm_error ("input file is empty or too short"); if (png_sig_cmp(sig_buf, (png_size_t) 0, (png_size_t) SIG_CHECK_SIZE) != 0) pm_error ("input file is not a PNG file"); } static void setupGammaCorrection(png_struct * const png_ptr, png_info * const info_ptr, float const displaygamma, float * const totalgammaP) { if (displaygamma == -1.0) *totalgammaP = -1.0; else { float imageGamma; if (info_ptr->valid & PNG_INFO_gAMA) imageGamma = info_ptr->gamma; else { if (verbose) pm_message("PNG doesn't specify image gamma. Assuming 1.0"); imageGamma = 1.0; } if (fabs(displaygamma * imageGamma - 1.0) < .01) { *totalgammaP = -1.0; if (verbose) pm_message("image gamma %4.2f matches " "display gamma %4.2f. No conversion.", imageGamma, displaygamma); } else { png_set_gamma(png_ptr, displaygamma, imageGamma); *totalgammaP = imageGamma * displaygamma; /* in case of gamma-corrections, sBIT's as in the PNG-file are not valid anymore */ info_ptr->valid &= ~PNG_INFO_sBIT; if (verbose) pm_message("image gamma is %4.2f, " "converted for display gamma of %4.2f", imageGamma, displaygamma); } } } static bool paletteHasPartialTransparency(png_info * const info_ptr) { bool retval; if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { if (info_ptr->valid & PNG_INFO_tRNS) { bool foundGray; unsigned int i; for (i = 0, foundGray = FALSE; i < info_ptr->num_trans && !foundGray; ++i) { if (info_ptr->TRANS_ALPHA[i] != 0 && info_ptr->TRANS_ALPHA[i] != maxval) { foundGray = TRUE; } } retval = foundGray; } else retval = FALSE; } else retval = FALSE; return retval; } static void getComponentSbitFg(png_info * const pngInfoP, png_byte * const fgSbitP, bool * const notUniformP) { if (pngInfoP->color_type == PNG_COLOR_TYPE_RGB || pngInfoP->color_type == PNG_COLOR_TYPE_RGB_ALPHA || pngInfoP->color_type == PNG_COLOR_TYPE_PALETTE) { if (pngInfoP->sig_bit.red == pngInfoP->sig_bit.blue && pngInfoP->sig_bit.red == pngInfoP->sig_bit.green) { *notUniformP = false; *fgSbitP = pngInfoP->sig_bit.red; } else *notUniformP = true; } else { /* It has only a gray channel so it's obviously uniform */ *notUniformP = false; *fgSbitP = pngInfoP->sig_bit.gray; } } static void getComponentSbit(png_info * const pngInfoP, enum alpha_handling const alphaHandling, png_byte * const componentSbitP, bool * const notUniformP) { switch (alphaHandling) { case ALPHA_ONLY: /* We care only about the alpha channel, so the uniform Sbit is the alpha Sbit */ *notUniformP = false; *componentSbitP = pngInfoP->sig_bit.alpha; break; case ALPHA_NONE: case ALPHA_MIX: /* We aren't going to produce an alpha channel, so we care only about the uniformity of the foreground channels. */ getComponentSbitFg(pngInfoP, componentSbitP, notUniformP); break; case ALPHA_IN: { /* We care about both the foreground and the alpha */ bool fgNotUniform; png_byte fgSbit; getComponentSbitFg(pngInfoP, &fgSbit, &fgNotUniform); if (fgNotUniform) *notUniformP = true; else { if (fgSbit == pngInfoP->sig_bit.alpha) { *notUniformP = false; *componentSbitP = fgSbit; } else *notUniformP = true; } } break; } } static void shiftPalette(png_info * const pngInfoP, unsigned int const shift) { /*---------------------------------------------------------------------------- Shift every component of every color in the PNG palette right by 'shift' bits because sBIT chunk says only those are significant. -----------------------------------------------------------------------------*/ if (shift > 7) pm_error("Invalid PNG: paletted image can't have " "more than 8 significant bits per component, " "but sBIT chunk says %u bits", shift); else { unsigned int i; for (i = 0; i < pngInfoP->num_palette; ++i) { pngInfoP->palette[i].red >>= (8 - shift); pngInfoP->palette[i].green >>= (8 - shift); pngInfoP->palette[i].blue >>= (8 - shift); } } } static void computeMaxvalFromSbit(png_struct * const pngP, png_info * const pngInfoP, enum alpha_handling const alphaHandling, png_uint_16 * const maxvalP, bool * const succeededP, int * const errorlevelP) { /* sBIT handling is very tricky. If we are extracting only the image, we can use the sBIT info for grayscale and color images, if the three values agree. If we extract the transparency/alpha mask, sBIT is irrelevant for trans and valid for alpha. If we mix both, the multiplication may result in values that require the normal bit depth, so we will use the sBIT info only for transparency, if we know that only solid and fully transparent is used */ bool notUniform; /* The sBIT chunk says the number of significant high-order bits in each component varies among the components we care about. */ png_byte componentSigBit; /* The number of high-order significant bits in each RGB component. Meaningless if they aren't all the same (i.e. 'notUniform') */ getComponentSbit(pngInfoP, alphaHandling, &componentSigBit, ¬Uniform); if (notUniform) { pm_message("This program cannot handle " "different bit depths for color channels"); pm_message("writing file with %u bit resolution", pngInfoP->bit_depth); *succeededP = false; *errorlevelP = PNMTOPNG_WARNING_LEVEL; } else if (componentSigBit > 15) { pm_message("Invalid PNG: says %u significant bits for a component; " "max possible is 16. Ignoring sBIT chunk.", componentSigBit); *succeededP = false; *errorlevelP = PNMTOPNG_WARNING_LEVEL; } else { if (alphaHandling == ALPHA_MIX && (pngInfoP->color_type == PNG_COLOR_TYPE_RGB_ALPHA || pngInfoP->color_type == PNG_COLOR_TYPE_GRAY_ALPHA || paletteHasPartialTransparency(pngInfoP))) *succeededP = false; else { if (componentSigBit < pngInfoP->bit_depth) { pm_message("Image has fewer significant bits, " "writing file with %u bits", componentSigBit); *maxvalP = (1l << componentSigBit) - 1; *succeededP = true; if (pngInfoP->color_type == PNG_COLOR_TYPE_PALETTE) shiftPalette(pngInfoP, componentSigBit); else png_set_shift(pngP, &pngInfoP->sig_bit); } else *succeededP = false; } } } static void setupSignificantBits(png_struct * const pngP, png_info * const pngInfoP, enum alpha_handling const alphaHandling, png_uint_16 * const maxvalP, int * const errorlevelP) { /*---------------------------------------------------------------------------- Figure out what maxval would best express the information in the PNG described by *pngP and *pngInfoP, with 'alpha' telling which information in the PNG we care about (image or alpha mask). Return the result as *maxvalP. Also set up *pngP for the corresponding significant bits. -----------------------------------------------------------------------------*/ bool gotItFromSbit; if (pngInfoP->valid & PNG_INFO_sBIT) computeMaxvalFromSbit(pngP, pngInfoP, alphaHandling, maxvalP, &gotItFromSbit, errorlevelP); else gotItFromSbit = false; if (!gotItFromSbit) { if (pngInfoP->color_type == PNG_COLOR_TYPE_PALETTE) { if (alphaHandling == ALPHA_ONLY) { if (pngInfoP->color_type == PNG_COLOR_TYPE_GRAY || pngInfoP->color_type == PNG_COLOR_TYPE_RGB) /* The alpha mask will be all opaque, so maxval 1 is plenty */ *maxvalP = 1; else if (paletteHasPartialTransparency(pngInfoP)) /* Use same maxval as PNG transparency palette for simplicity */ *maxvalP = 255; else /* A common case, so we conserve bits */ *maxvalP = 1; } else /* Use same maxval as PNG palette for simplicity */ *maxvalP = 255; } else { *maxvalP = (1l << pngInfoP->bit_depth) - 1; } } } static bool imageHasColor(png_info * const info_ptr) { bool retval; if (info_ptr->color_type == PNG_COLOR_TYPE_GRAY || info_ptr->color_type == PNG_COLOR_TYPE_GRAY_ALPHA) retval = FALSE; else if (info_ptr->color_type == PNG_COLOR_TYPE_PALETTE) { bool foundColor; unsigned int i; for (i = 0, foundColor = FALSE; i < info_ptr->num_palette && !foundColor; ++i) { if (iscolor(info_ptr->palette[i])) foundColor = TRUE; } retval = foundColor; } else retval = TRUE; return retval; } static void determineOutputType(png_info * const pngInfoP, enum alpha_handling const alphaHandling, pngcolor const bgColor, xelval const maxval, int * const formatP, unsigned int * const depthP, char * const tupleType) { if (alphaHandling == ALPHA_ONLY) { /* The output is a old style pseudo-PNM transparency image */ *depthP = 1; *formatP = maxval > 1 ? PGM_FORMAT : PBM_FORMAT; } else { /* The output is a normal Netpbm image */ bool const outputIsColor = imageHasColor(pngInfoP) || !isGrayscale(bgColor); if (alphaHandling == ALPHA_IN) { *formatP = PAM_FORMAT; if (outputIsColor) { *depthP = 4; strcpy(tupleType, "RGB_ALPHA"); } else { *depthP = 2; strcpy(tupleType, "GRAYSCALE_ALPHA"); } } else { if (outputIsColor) { *formatP = PPM_FORMAT; *depthP = 3; } else { *depthP = 1; *formatP = maxval > 1 ? PGM_FORMAT : PBM_FORMAT; } } } } static void getBackgroundColor(png_info * const info_ptr, const char * const requestedColor, float const totalgamma, xelval const maxval, pngcolor * const bgColorP) { /*---------------------------------------------------------------------------- Figure out what the background color should be. If the user requested a particular color ('requestedColor' not null), that's the one. Otherwise, if the PNG specifies a background color, that's the one. And otherwise, it's white. -----------------------------------------------------------------------------*/ if (requestedColor) { /* Background was specified from the command-line; we always use that. I chose to do no gamma-correction in this case; which is a bit arbitrary. */ pixel const backcolor = ppm_parsecolor(requestedColor, maxval); bgColorP->r = PPM_GETR(backcolor); bgColorP->g = PPM_GETG(backcolor); bgColorP->b = PPM_GETB(backcolor); } else if (info_ptr->valid & PNG_INFO_bKGD) { /* didn't manage to get libpng to work (bugs?) concerning background processing, therefore we do our own. */ switch (info_ptr->color_type) { case PNG_COLOR_TYPE_GRAY: case PNG_COLOR_TYPE_GRAY_ALPHA: bgColorP->r = bgColorP->g = bgColorP->b = gamma_correct(info_ptr->background.gray, totalgamma); break; case PNG_COLOR_TYPE_PALETTE: { png_color const rawBgcolor = info_ptr->palette[info_ptr->background.index]; bgColorP->r = gamma_correct(rawBgcolor.red, totalgamma); bgColorP->g = gamma_correct(rawBgcolor.green, totalgamma); bgColorP->b = gamma_correct(rawBgcolor.blue, totalgamma); } break; case PNG_COLOR_TYPE_RGB: case PNG_COLOR_TYPE_RGB_ALPHA: { png_color_16 const rawBgcolor = info_ptr->background; bgColorP->r = gamma_correct(rawBgcolor.red, totalgamma); bgColorP->g = gamma_correct(rawBgcolor.green, totalgamma); bgColorP->b = gamma_correct(rawBgcolor.blue, totalgamma); } break; } } else /* when no background given, we use white [from version 2.37] */ bgColorP->r = bgColorP->g = bgColorP->b = maxval; } #define GET_PNG_VAL(p) get_png_val(&(p), pngInfoP->bit_depth) static void makeTupleRow(const struct pam * const pamP, const tuple * const tuplerow, png_info * const pngInfoP, const png_byte * const pngRasterRow, pngcolor const bgColor, enum alpha_handling const alphaHandling, double const totalgamma) { const png_byte * pngPixelP; unsigned int col; pngPixelP = &pngRasterRow[0]; /* initial value */ for (col = 0; col < pngInfoP->width; ++col) { switch (pngInfoP->color_type) { case PNG_COLOR_TYPE_GRAY: { pngcolor fgColor; fgColor.r = fgColor.g = fgColor.b = GET_PNG_VAL(pngPixelP); setTuple(pamP, tuplerow[col], fgColor, bgColor, alphaHandling, isTransparentColor(fgColor, pngInfoP, totalgamma) ? 0 : maxval); } break; case PNG_COLOR_TYPE_GRAY_ALPHA: { pngcolor fgColor; png_uint_16 alpha; fgColor.r = fgColor.g = fgColor.b = GET_PNG_VAL(pngPixelP); alpha = GET_PNG_VAL(pngPixelP); setTuple(pamP, tuplerow[col], fgColor, bgColor, alphaHandling, alpha); } break; case PNG_COLOR_TYPE_PALETTE: { png_uint_16 const index = GET_PNG_VAL(pngPixelP); png_color const paletteColor = pngInfoP->palette[index]; pngcolor fgColor; fgColor.r = paletteColor.red; fgColor.g = paletteColor.green; fgColor.b = paletteColor.blue; setTuple(pamP, tuplerow[col], fgColor, bgColor, alphaHandling, (pngInfoP->valid & PNG_INFO_tRNS) && index < pngInfoP->num_trans ? pngInfoP->TRANS_ALPHA[index] : maxval); } break; case PNG_COLOR_TYPE_RGB: { pngcolor fgColor; fgColor.r = GET_PNG_VAL(pngPixelP); fgColor.g = GET_PNG_VAL(pngPixelP); fgColor.b = GET_PNG_VAL(pngPixelP); setTuple(pamP, tuplerow[col], fgColor, bgColor, alphaHandling, isTransparentColor(fgColor, pngInfoP, totalgamma) ? 0 : maxval); } break; case PNG_COLOR_TYPE_RGB_ALPHA: { pngcolor fgColor; png_uint_16 alpha; fgColor.r = GET_PNG_VAL(pngPixelP); fgColor.g = GET_PNG_VAL(pngPixelP); fgColor.b = GET_PNG_VAL(pngPixelP); alpha = GET_PNG_VAL(pngPixelP); setTuple(pamP, tuplerow[col], fgColor, bgColor, alphaHandling, alpha); } break; default: pm_error("unknown PNG color type: %d", pngInfoP->color_type); } } } static void reportOutputFormat(const struct pam * const pamP) { switch (pamP->format) { case PBM_FORMAT: pm_message("Writing a PBM file"); break; case PGM_FORMAT: pm_message("Writing a PGM file with maxval %lu", pamP->maxval); break; case PPM_FORMAT: pm_message("Writing a PPM file with maxval %lu", pamP->maxval); break; case PAM_FORMAT: pm_message("Writing a PAM file with tuple type %s, maxval %u", pamP->tuple_type, maxval); break; default: assert(false); /* Every possible value handled above */ } } static void writeNetpbm(struct pam * const pamP, png_info * const pngInfoP, png_byte ** const pngRaster, pngcolor const bgColor, enum alpha_handling const alphaHandling, double const totalgamma) { /*---------------------------------------------------------------------------- Write a Netpbm image of either the image or the alpha mask, according to 'alphaHandling' that is in the PNG image described by 'pngInfoP' and pngRaster. *pamP describes the required output image and is consistent with *pngInfoP. Use background color 'bgColor' in the output if the PNG is such that a background color is needed. -----------------------------------------------------------------------------*/ tuple * tuplerow; unsigned int row; if (verbose) reportOutputFormat(pamP); pnm_writepaminit(pamP); tuplerow = pnm_allocpamrow(pamP); for (row = 0; row < pngInfoP->height; ++row) { makeTupleRow(pamP, tuplerow, pngInfoP, pngRaster[row], bgColor, alphaHandling, totalgamma); pnm_writepamrow(pamP, tuplerow); } pnm_freepamrow(tuplerow); } static void convertpng(FILE * const ifp, FILE * const tfp, struct cmdlineInfo const cmdline, int * const errorlevelP) { png_struct * png_ptr; png_info * info_ptr; png_byte ** png_image; pngcolor bgColor; float totalgamma; struct pam pam; *errorlevelP = 0; read_sig_buf(ifp); png_ptr = png_create_read_struct( PNG_LIBPNG_VER_STRING, &pngtopnm_jmpbuf_struct, pngtopnm_error_handler, NULL); if (png_ptr == NULL) pm_error("cannot allocate main libpng structure (png_ptr)"); info_ptr = png_create_info_struct (png_ptr); if (info_ptr == NULL) pm_error("cannot allocate LIBPNG structures"); if (setjmp(pngtopnm_jmpbuf_struct.jmpbuf)) pm_error ("setjmp returns error condition"); png_init_io (png_ptr, ifp); png_set_sig_bytes (png_ptr, SIG_CHECK_SIZE); png_read_info (png_ptr, info_ptr); allocPngRaster(info_ptr, &png_image); if (info_ptr->bit_depth < 8) png_set_packing (png_ptr); setupGammaCorrection(png_ptr, info_ptr, cmdline.gamma, &totalgamma); setupSignificantBits(png_ptr, info_ptr, cmdline.alpha, &maxval, errorlevelP); getBackgroundColor(info_ptr, cmdline.background, totalgamma, maxval, &bgColor); png_read_image(png_ptr, png_image); png_read_end(png_ptr, info_ptr); if (verbose) /* Note that some of info_ptr is not defined until png_read_end() completes. That's because it comes from chunks that are at the end of the stream. */ dump_png_info(info_ptr); if (cmdline.time) show_time(info_ptr); if (tfp) save_text(info_ptr, tfp); if (info_ptr->valid & PNG_INFO_pHYs) { float const r = (float)info_ptr->x_pixels_per_unit / info_ptr->y_pixels_per_unit; if (r != 1.0) { pm_message ("warning - non-square pixels; " "to fix do a 'pamscale -%cscale %g'", r < 1.0 ? 'x' : 'y', r < 1.0 ? 1.0 / r : r ); *errorlevelP = PNMTOPNG_WARNING_LEVEL; } } pam.size = sizeof(pam); pam.len = PAM_STRUCT_SIZE(tuple_type); pam.file = stdout; pam.plainformat = 0; pam.height = info_ptr->height; pam.width = info_ptr->width; pam.maxval = maxval; determineOutputType(info_ptr, cmdline.alpha, bgColor, maxval, &pam.format, &pam.depth, pam.tuple_type); writeNetpbm(&pam, info_ptr, png_image, bgColor, cmdline.alpha, totalgamma); fflush(stdout); freePngRaster(png_image, info_ptr); png_destroy_read_struct(&png_ptr, &info_ptr, NULL); } int main(int argc, const char *argv[]) { struct cmdlineInfo cmdline; FILE * ifP; FILE * tfP; int errorlevel; pm_proginit(&argc, argv); parseCommandLine(argc, argv, &cmdline); verbose = cmdline.verbose; ifP = pm_openr(cmdline.inputFilespec); if (cmdline.text) tfP = pm_openw(cmdline.text); else tfP = NULL; convertpng(ifP, tfP, cmdline, &errorlevel); if (tfP) pm_close(tfP); pm_close(ifP); pm_close(stdout); return errorlevel; }