/***************************************************************************** bmptopnm.c ****************************************************************************** Bmptopnm - Converts from a Microsoft Windows or OS/2 .BMP file to a PBM, PGM, or PPM file. This program was formerly called Bmptoppm (and generated only PPM output). The name was changed in March 2002. Copyright (C) 1992 by David W. Sanderson. 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. Note: From mid-2003 to mid-2007, this program would crash on any 16 bit BMP without transparency and no one reported it. Before that, it refused to even try to read a 16 bit BMP. I conclude that essentially nobody is using 16 bit BMP. *****************************************************************************/ #include #include #include #include "pm_c_util.h" #include "pnm.h" #include "shhopt.h" #include "nstring.h" #include "bmp.h" /* MAXCOLORS is the maximum size of a color map in a BMP image */ #define MAXCOLORS 256 static xelval const bmpMaxval = 255; /* The maxval for intensity values in a BMP image -- either in a truecolor raster or in a colormap */ enum rowOrder {BOTTOMUP, TOPDOWN}; struct bitPosition { /* mask and shift count to describe a set of bits in a binary value. Example: if 16 bits are laid out as XRRRRRGGGGGBBBBB then the shift count for the R component is 10 and the mask is 0000000000011111. A 'mask' of zero denotes absence of any bits; e.g. in the example above, the mask for the transparency component is zero because there is no transparency component . 'shift' is arbitrary in that case. */ unsigned int shift; /* How many bits right you have to shift the value to get the subject bits in the least significant bit positions. */ unsigned int mask; /* Has one bits in positions where the subject bits are after shifting. */ }; struct pixelformat { /* The format of a pixel representation from the raster. i.e. which bits apply to red, green, blue, and transparency */ struct bitPosition red; struct bitPosition blu; struct bitPosition grn; struct bitPosition trn; bool conventionalBgr; /* This means that the above bit positions are just the conventional BGR format -- one byte Blue, one byte Green, one byte Red, no alpha. Though it's totally redundant with the members above, this member speeds up computation: We've never actually seen a BMP file that doesn't use conventional BGR, and it doesn't require any masking or shifting at all to interpret. */ }; struct bmpInfoHeader { enum rowOrder rowOrder; int cols; int rows; unsigned int cBitCount; /* Number of bits in the BMP file that each pixel occupies. */ enum bmpClass class; bool bitFields; /* The raster values are arranged in arbitrary bit fields as described by the "mask" values in the header, rather than fixed formats. */ unsigned int cmapsize; /* Size in bytes of the colormap (palette) in the BMP file. Zero means there is no colormap. */ unsigned int imageSize; /* Size in bytes of the image data. We only reference this when the image is compressed. */ unsigned short cPlanes; unsigned long int compression; struct pixelformat pixelformat; }; struct cmdline_info { /* All the information the user supplied in the command line, in a form easy for the program to use. */ const char *input_filespec; /* Filespecs of input files */ int verbose; /* -verbose option */ }; static const char *ifname; static void parse_command_line(int argc, char ** argv, struct cmdline_info *cmdline_p) { /*---------------------------------------------------------------------------- Note that the file spec array we return is stored in the storage that was passed to us as the argv array. -----------------------------------------------------------------------------*/ optStruct *option_def = malloc(100*sizeof(optStruct)); /* Instructions to OptParseOptions2 on how to parse our options. */ optStruct2 opt; unsigned int option_def_index; option_def_index = 0; /* incremented by OPTENTRY */ OPTENTRY(0, "verbose", OPT_FLAG, &cmdline_p->verbose, 0); /* Set the defaults */ cmdline_p->verbose = FALSE; 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 */ optParseOptions2(&argc, argv, opt, 0); /* Uses and sets argc, argv, and some of *cmdline_p and others. */ if (argc-1 == 0) cmdline_p->input_filespec = "-"; else if (argc-1 != 1) pm_error("Program takes zero or one argument (filename). You " "specified %d", argc-1); else cmdline_p->input_filespec = argv[1]; } static const char er_read[] = "%s: read error"; static int GetByte(FILE * const fp) { int v; if ((v = getc(fp)) == EOF) pm_error(er_read, ifname); return v; } static short GetShort(FILE * const fp) { short v; if (pm_readlittleshort(fp, &v) == -1) pm_error(er_read, ifname); return v; } static short GetBigShort(FILE * const fp) { short v; if (pm_readbigshort(fp, &v) == -1) pm_error(er_read, ifname); return v; } static long GetLong(FILE * const fp) { long v; if (pm_readlittlelong(fp, &v) == -1) pm_error(er_read, ifname); return v; } typedef struct { long dummy[12]; } cieXyzTriple; static cieXyzTriple GetCieXyzTriple(FILE * const fp) { cieXyzTriple v; unsigned int i; for (i = 0; i < 12; ++i) if (pm_readlittlelong(fp, &v.dummy[i]) == -1) pm_error(er_read, ifname); return v; } static void readOffBytes(FILE * const fp, unsigned int const nbytes) { /*---------------------------------------------------------------------------- Read 'nbytes' from file 'fp'. Abort program if read error. -----------------------------------------------------------------------------*/ int i; for(i = 0; i < nbytes; ++i) { int rc; rc = getc(fp); if (rc == EOF) pm_error(er_read, ifname); } } static void BMPreadfileheader(FILE * const ifP, unsigned int * const bytesReadP, unsigned int * const offBitsP) { unsigned short xHotSpot; unsigned short yHotSpot; unsigned long offBits; unsigned long int fileSize; if (GetByte(ifP) != 'B') pm_error("'%s' is not a BMP file. (It doesn't start with 'BM')", ifname); if (GetByte(ifP) != 'M') pm_error("'%s' is not a BMP file. (It doesn't start with 'BM')", ifname); fileSize = GetLong(ifP); /* This is not always reliable. */ xHotSpot = GetShort(ifP); yHotSpot = GetShort(ifP); offBits = GetLong(ifP); *offBitsP = offBits; *bytesReadP = 14; } static void readOs2InfoHeader(FILE * const ifP, struct bmpInfoHeader * const headerP) { headerP->class = C_OS2; headerP->cols = GetShort(ifP); headerP->rows = GetShort(ifP); headerP->rowOrder = BOTTOMUP; headerP->cPlanes = GetShort(ifP); headerP->cBitCount = GetShort(ifP); /* I actually don't know if the OS/2 BMP format allows cBitCount > 8 or if it does, what it means, but ppmtobmp creates such BMPs, more or less as a byproduct of creating the same for Windows BMP, so we interpret cBitCount > 8 the same as for Windows. */ if (headerP->cBitCount <= 8) headerP->cmapsize = 1 << headerP->cBitCount; else if (headerP->cBitCount == 24) headerP->cmapsize = 0; /* There is a 16 bit truecolor format, but we don't know how the bits are divided among red, green, and blue, so we can't handle it. */ else pm_error("Unrecognized bits per pixel in OS/2 BMP file header: %d", headerP->cBitCount); headerP->compression = COMP_RGB; pm_message("OS/2 BMP, %dx%dx%d", headerP->cols, headerP->rows, headerP->cBitCount); } static void validateCompression(unsigned long const compression, enum rowOrder const rowOrder, unsigned int const cBitCount) { if (compression != COMP_RGB && compression != COMP_BITFIELDS && compression != COMP_RLE4 && compression != COMP_RLE8 ) pm_error("Input has unknown encoding. " "Compression type code = %ld. The only ones we know " "are RGB (%u), BITFIELDS (%u), " "RLE4 (%u), and RLE8 (%u)", compression, COMP_RGB, COMP_BITFIELDS, COMP_RLE4, COMP_RLE8); if ((compression == COMP_RLE4 || compression == COMP_RLE8) && rowOrder == TOPDOWN ) pm_error("Invalid BMP header. Claims image is top-down and also " "compressed, which is an impossible combination."); if ( (compression == COMP_RLE4 && cBitCount !=4) || (compression == COMP_RLE8 && cBitCount !=8) ) pm_error("Invalid BMP header. " "Compression type (%s) disagrees with " "number of bits per pixel (%u).", compression == COMP_RLE4 ? "RLE4" : "RLE8", cBitCount); } static void readWindowsBasic40ByteInfoHeader(FILE * const ifP, struct bmpInfoHeader * const headerP) { /*---------------------------------------------------------------------------- Read from the file stream 'ifP' the basic BMP Info header. This does not include any Info header extension. The Info header is the data that comes after the BMP file header. Return the information from the info header as *headerP. -----------------------------------------------------------------------------*/ int colorsimportant; /* ColorsImportant value from header */ int colorsused; /* ColorsUsed value from header */ headerP->class = C_WIN; headerP->cols = GetLong(ifP); { long const cy = GetLong(ifP); if (cy == 0) pm_error("Invalid BMP file: says height is zero"); if (cy < 0) { headerP->rowOrder = TOPDOWN; headerP->rows = - cy; } else { headerP->rowOrder = BOTTOMUP; headerP->rows = cy; } } headerP->cPlanes = GetShort(ifP); headerP->cBitCount = GetShort(ifP); { unsigned long int const compression = GetLong(ifP); headerP->bitFields = (compression == COMP_BITFIELDS); validateCompression(compression, headerP->rowOrder, headerP->cBitCount); headerP->compression = compression; } /* And read the rest of the junk in the 40 byte header */ headerP->imageSize = GetLong(ifP); /* ImageSize */ GetLong(ifP); /* XpixelsPerMeter */ GetLong(ifP); /* YpixelsPerMeter */ colorsused = GetLong(ifP); /* ColorsUsed */ /* See comments in bmp.h for info about the definition of the following word and its relationship to the color map size (headerP->cmapsize). */ colorsimportant = GetLong(ifP); /* ColorsImportant */ if (headerP->cBitCount <= 8) { if (colorsused != 0) { if (colorsused > 1 << headerP->cBitCount) pm_error("Invalid BMP header. Says %u bits per pixel, " "but %d colors used", headerP->cBitCount, colorsused); else headerP->cmapsize = colorsused; } else headerP->cmapsize = 1 << headerP->cBitCount; } else if (headerP->cBitCount == 24 || headerP->cBitCount == 16 || headerP->cBitCount == 32) headerP->cmapsize = 0; else pm_error("Unrecognized bits per pixel in Windows BMP file header: %d", headerP->cBitCount); } static unsigned int lsbZeroCount(unsigned int const mask) /*---------------------------------------------------------------------------- Return the number of consecutive zeroes in the mask 'mask', starting with the least significant bit and going up. E.g. for 0x20, it would be 5. Use GCC built-in when available. -----------------------------------------------------------------------------*/ #if HAVE_GCC_BITCOUNT { return ( mask==0 ? sizeof(mask)*8 : __builtin_ctz(mask) ); } #else { unsigned int i=0; while (((mask >> i) & 0x1) == 0 && i < sizeof(mask)*8) ++i; return i; } #endif static struct bitPosition bitPositionFromMask(long const bmpMask) { struct bitPosition retval; retval.shift = lsbZeroCount(bmpMask); retval.mask = bmpMask >> retval.shift; return retval; } static void computeConventionalBgr(struct pixelformat * const fP, unsigned int const bitCount) { switch (bitCount) { case 24: fP->conventionalBgr = fP->red.shift == 0 && fP->red.mask == 0xFF && fP->grn.shift == 8 && fP->grn.mask == 0xFF && fP->blu.shift == 16 && fP->blu.mask == 0xFF && fP->trn.mask == 0 ; break; case 32: fP->conventionalBgr = fP->red.shift == 8 && fP->red.mask == 0xFF && fP->grn.shift == 16 && fP->grn.mask == 0xFF && fP->blu.shift == 24 && fP->blu.mask == 0xFF && fP->trn.mask == 0 ; break; default: fP->conventionalBgr = FALSE; } } static struct pixelformat defaultPixelformat(unsigned int const bitCount) { struct pixelformat retval; switch (bitCount) { case 16: /* This layout is sometimes called "RGB555". A document from Microsoft says this is the default (when the "compression" field of the header says COMP_BITFIELDS). */ retval.conventionalBgr = FALSE; retval.red.shift = 10; retval.grn.shift = 5; retval.blu.shift = 0; retval.trn.shift = 0; retval.red.mask = 0x1f; /* 5 bits */ retval.grn.mask = 0x1f; /* 5 bits */ retval.blu.mask = 0x1f; /* 5 bits */ retval.trn.mask = 0; break; case 24: case 32: retval.conventionalBgr = TRUE; retval.red.shift = 16; retval.grn.shift = 8; retval.blu.shift = 0; retval.trn.shift = 0; retval.red.mask = 0xff; /* 8 bits */ retval.grn.mask = 0xff; /* 8 bits */ retval.blu.mask = 0xff; /* 8 bits */ retval.trn.mask = 0; break; default: /* colormapped - masks are undefined */ break; } return retval; } static void readV4InfoHeaderExtension(FILE * const ifP, struct bmpInfoHeader * const headerP) { if (headerP->bitFields) { /* A document from Microsoft says on Windows 95 there is no transparency plane and (red, green, blue) must be either (5,5,5) or (5,6,5) for 16 bit and (8,8,8) for 32 bit. It calls these RGB555, RGB565, RGB888. */ headerP->pixelformat.red = bitPositionFromMask(GetLong(ifP)); headerP->pixelformat.grn = bitPositionFromMask(GetLong(ifP)); headerP->pixelformat.blu = bitPositionFromMask(GetLong(ifP)); headerP->pixelformat.trn = bitPositionFromMask(GetLong(ifP)); computeConventionalBgr(&headerP->pixelformat, headerP->cBitCount); } else headerP->pixelformat = defaultPixelformat(headerP->cBitCount); GetLong(ifP); /* Color space */ GetCieXyzTriple(ifP); /* Endpoints */ GetLong(ifP); /* GammaRed */ GetLong(ifP); /* GammaGreen */ GetLong(ifP); /* GammaBlue */ } static void defaultV4InfoHeaderExtension(struct bmpInfoHeader * const headerP) { headerP->pixelformat = defaultPixelformat(headerP->cBitCount); } static void readWindowsInfoHeader(FILE * const ifP, unsigned int const cInfoHeaderSize, struct bmpInfoHeader * const headerP) { /* There are 3 major formats of Windows BMP, identified by the 3 info header lengths. The original one is 40 bytes. The "V4 header" is 108 bytes and was new with Windows 95 and NT 4.0. The "V5 header" is 124 bytes and was new with Windows 98 and Windows 2000. */ readWindowsBasic40ByteInfoHeader(ifP, headerP); if (cInfoHeaderSize >= 108) readV4InfoHeaderExtension(ifP, headerP); else defaultV4InfoHeaderExtension(headerP); if (cInfoHeaderSize >= 124) { /* Read off the V5 info header extension. */ GetLong(ifP); /* Intent */ GetLong(ifP); /* ProfileData */ GetLong(ifP); /* ProfileSize */ GetLong(ifP); /* Reserved */ } pm_message("Windows BMP, %dx%dx%d", headerP->cols, headerP->rows, headerP->cBitCount); } static void BMPreadinfoheader(FILE * const ifP, unsigned int * const bytesReadP, struct bmpInfoHeader * const headerP) { unsigned int const cInfoHeaderSize = GetLong(ifP); switch (cInfoHeaderSize) { case 12: readOs2InfoHeader(ifP, headerP); break; case 40: case 108: case 124: readWindowsInfoHeader(ifP, cInfoHeaderSize, headerP); break; default: pm_error("%s: unknown Info Header size: %u bytes", ifname, cInfoHeaderSize); break; } *bytesReadP = cInfoHeaderSize; } static void BMPreadcolormap(FILE * const ifP, int const class, xel ** const colormapP, unsigned int const cmapsize, unsigned int * const bytesReadP) { /*---------------------------------------------------------------------------- Read the color map from the present position in the input BMP file *ifP. The map has 'cmapsize' entries in it. cmapsize == 0 means there is no color map. We return a color map as *colormapP. If there is no color map in the BMP, this is just an arbitrary color map. 'class' is the class of BMP image - Windows or OS/2. -----------------------------------------------------------------------------*/ unsigned int i; xel * colormap; unsigned int bytesRead; colormap = pnm_allocrow(MAX(1,cmapsize)); bytesRead = 0; /* initial value */ for (i = 0; i < cmapsize; ++i) { /* There is a document that says the bytes are ordered R,G,B,Z, but in practice it appears to be the following instead: */ unsigned int r, g, b; b = GetByte(ifP); g = GetByte(ifP); r = GetByte(ifP); PNM_ASSIGN(colormap[i], r, g, b); bytesRead += 3; if (class == C_WIN) { GetByte(ifP); bytesRead += 1; } } *colormapP = colormap; *bytesReadP = bytesRead; } static void extractBitFields(unsigned int const rasterval, struct pixelformat const pixelformat, pixval const maxval, pixval * const rP, pixval * const gP, pixval * const bP, pixval * const aP) { unsigned int const rbits = (rasterval >> pixelformat.red.shift) & pixelformat.red.mask; unsigned int const gbits = (rasterval >> pixelformat.grn.shift) & pixelformat.grn.mask; unsigned int const bbits = (rasterval >> pixelformat.blu.shift) & pixelformat.blu.mask; unsigned int const abits = (rasterval >> pixelformat.trn.shift) & pixelformat.trn.mask; *rP = pixelformat.red.mask > 0 ? (unsigned int) rbits * maxval / pixelformat.red.mask : 0; *gP = pixelformat.grn.mask > 0 ? (unsigned int) gbits * maxval / pixelformat.grn.mask : 0; *bP = pixelformat.blu.mask > 0 ? (unsigned int) bbits * maxval / pixelformat.blu.mask : 0; *aP = pixelformat.trn.mask > 0 ? (unsigned int) abits * maxval / pixelformat.trn.mask : 0; } static void convertRow16(unsigned char const bmprow[], xel xelrow[], int const cols, struct pixelformat const pixelformat) { /* It's truecolor. */ unsigned int col; unsigned int cursor; cursor = 0; for (col=0; col < cols; ++col) { unsigned short const rasterval = (unsigned short) bmprow[cursor+1] << 8 | bmprow[cursor+0]; pixval r, g, b, a; extractBitFields(rasterval, pixelformat, 255, &r, &g, &b, &a); PNM_ASSIGN(xelrow[col], r, g, b); cursor += 2; } } static void convertRow24(unsigned char const bmprow[], xel xelrow[], int const cols, struct pixelformat const pixelformat) { /* It's truecolor */ /* There is a document that gives a much different format for 24 bit BMPs. But this seems to be the de facto standard, and is, with a little ambiguity and contradiction resolved, defined in the Microsoft BMP spec. */ unsigned int col; unsigned int cursor; cursor = 0; for (col = 0; col < cols; ++col) { pixval r, g, b, a; if (pixelformat.conventionalBgr) { r = bmprow[cursor+2]; g = bmprow[cursor+1]; b = bmprow[cursor+0]; a = 0; } else { unsigned int const rasterval = (bmprow[cursor+0] << 16) + (bmprow[cursor+1] << 8) + (bmprow[cursor+2] << 0); extractBitFields(rasterval, pixelformat, 255, &r, &g, &b, &a); } PNM_ASSIGN(xelrow[col], r, g, b); cursor += 3; } } static void convertRow32(unsigned char const bmprow[], xel xelrow[], int const cols, struct pixelformat const pixelformat) { /* It's truecolor */ unsigned int col; unsigned int cursor; cursor = 0; for (col = 0; col < cols; ++col) { pixval r, g, b, a; if (pixelformat.conventionalBgr) { /* bmprow[cursor+3] is just padding */ r = bmprow[cursor+2]; g = bmprow[cursor+1]; b = bmprow[cursor+0]; a = 0; } else { unsigned int const rasterval = (bmprow[cursor+0] << 24) + (bmprow[cursor+1] << 16) + (bmprow[cursor+2] << 8) + (bmprow[cursor+3] << 0); extractBitFields(rasterval, pixelformat, 255, &r, &g, &b, &a); } PNM_ASSIGN(xelrow[col], bmprow[cursor+2], bmprow[cursor+1], bmprow[cursor+0]); cursor += 4; } } static void convertRow(unsigned char const bmprow[], xel xelrow[], int const cols, unsigned int const cBitCount, struct pixelformat const pixelformat, xel const colormap[] ) { /*---------------------------------------------------------------------------- Convert a row in raw BMP raster format bmprow[] to a row of xels xelrow[]. Use maxval 255 for the output xels. The BMP image has 'cBitCount' bits per pixel. If the image is colormapped, colormap[] is the colormap (colormap[i] is the color with color index i). -----------------------------------------------------------------------------*/ if (cBitCount == 24) convertRow24(bmprow, xelrow, cols, pixelformat); else if (cBitCount == 16) convertRow16(bmprow, xelrow, cols, pixelformat); else if (cBitCount == 32) convertRow32(bmprow, xelrow, cols, pixelformat); else if (cBitCount == 8) { /* It's a whole byte colormap index */ unsigned int col; for (col = 0; col < cols; ++col) xelrow[col] = colormap[bmprow[col]]; } else if (cBitCount < 8) { /* It's a bit field color index */ unsigned char const mask = ( 1 << cBitCount ) - 1; unsigned int col; for (col = 0; col < cols; ++col) { unsigned int const cursor = (col*cBitCount)/8; unsigned int const shift = 8 - ((col*cBitCount) % 8) - cBitCount; unsigned int const index = (bmprow[cursor] & (mask << shift)) >> shift; xelrow[col] = colormap[index]; } } else pm_error("Internal error: invalid cBitCount in convertRow()"); } static unsigned char ** allocBMPraster(unsigned int const rows, unsigned int const bytesPerRow) { unsigned int const storageSize = rows * sizeof(unsigned char *) + rows * bytesPerRow; unsigned char ** BMPraster; unsigned int row; unsigned char * startOfRows; /* The raster array consists of an array of pointers to the rows followed by the rows of bytes, in a single allocated chunk of storage. */ if (UINT_MAX / (bytesPerRow + sizeof(unsigned char *)) < rows) pm_error("raster is ridiculously large."); BMPraster = (unsigned char **) malloc(storageSize); if (BMPraster == NULL) pm_error("Unable to allocate %u bytes for the BMP raster\n", storageSize); startOfRows = (unsigned char *)(BMPraster + rows); for (row = 0; row < rows; ++row) BMPraster[row] = startOfRows + row * bytesPerRow; return BMPraster; } static void readrow(FILE * const ifP, unsigned int const row, unsigned int const bytesPerRow, unsigned char ** const BMPraster, unsigned int * const bytesReadP) { size_t bytesRead; assert(bytesPerRow > 0); bytesRead = fread(BMPraster[row], 1, bytesPerRow, ifP); if (bytesRead < bytesPerRow) { if (feof(ifP)) pm_error("End of file reading row %u of BMP raster.", row); else pm_error("Error reading BMP raster. Errno=%d (%s)", errno, strerror(errno)); } *bytesReadP += bytesRead; } static void nibbleAlign(unsigned char * const ptr, unsigned int const nibbles){ /*---------------------------------------------------------------------------- Shift data pointed by ptr one half byte toward the MSB (to the left). Example: (Numbers in hex, 8 nibbles) 5F 13 7E 89 A1 becomes 51 37 E8 9A 10 -----------------------------------------------------------------------------*/ unsigned int const fullByteCount = (nibbles-1) / 2; unsigned int i; ptr[0] = ptr[0] & ptr[1] >> 4; for (i = 0; i < fullByteCount; ++i) ptr[i+1] = ptr[i+1] << 4 & ptr[i+2] >> 4; if (nibbles % 2 == 1) /* if there is a final odd nibble */ ptr[fullByteCount+1] <<= 4; /* shift it a half byte */ } enum rleStatus { ABS_MODE, ENC_MODE, END_OF_ROW, END_OF_BMP, DELTA }; static enum rleStatus readRLEcode(FILE * const ifP, unsigned int * const cntP, unsigned char * const codeP) { unsigned short s; enum rleStatus retval; s = GetBigShort(ifP); if (s == 0) retval = END_OF_ROW; else if (s == 1) retval = END_OF_BMP; else if (s == 2) retval = DELTA; else if (s < 256) { if (cntP) *cntP = s & 0xff; retval = ABS_MODE; } else { if (cntP && codeP) { *cntP = (s >> 8) & 0xff; *codeP = s & 0xff; } retval = ENC_MODE; } return retval; } static void readrowRLE(FILE * const ifP, unsigned int const row, unsigned int const cols, bool const lastrow, unsigned long const compression, unsigned char ** const BMPraster, unsigned int * const bytesReadP) { bool const RLE4 = (compression == COMP_RLE4); int const pixelsPerRowMargin = RLE4 ? cols % 2 : 0; char const err_decode[] = "Error while decoding compressed BMP image. " "%s. Row: %u Pixel: %u" ; unsigned int totalBytesRead; unsigned int pixelsRead; /* There are RLE4 images with rows coded up the byte boundary, resulting in each row one pixel larger than the column length stated in the BMP info header (header.cols) when the column length is odd. pixelsPerRowMargin is a "wart" to provide for this case. */ totalBytesRead = 0; /* Initial value */ pixelsRead = 0; /* Initial value */ while (TRUE) { unsigned int n; /* decompressed bytes already read; current write point */ unsigned int cnt; unsigned char code; n = RLE4 ? (pixelsRead + 1) / 2 : pixelsRead; switch (readRLEcode(ifP, &cnt, &code)) { case ENC_MODE: { unsigned int const byteCnt = RLE4 ? (cnt + 1) /2 : cnt; unsigned int i; if (pixelsRead + cnt > cols + pixelsPerRowMargin) pm_error(err_decode, "Too many pixels in encoded mode", row, pixelsRead ); for (i = 0; i < byteCnt; ++i) BMPraster[row][n+i] = code; if (RLE4 && pixelsRead % 2 == 1) /* previous read ended odd */ nibbleAlign(&BMPraster[row][n-1], cnt); pixelsRead += cnt; totalBytesRead += 2; } break; case ABS_MODE: { unsigned int cmpBytesRead; /* compressed bytes read */ /* align read-end to 16 bit boundary */ unsigned int const bytesToRead = RLE4 ? (cnt + 3) / 4 * 2 : (cnt + 1) / 2 * 2; if (pixelsRead + cnt > cols + pixelsPerRowMargin) pm_error(err_decode, "Too many pixels in absolute mode", row, pixelsRead); cmpBytesRead = fread(&BMPraster[row][n], sizeof(char), bytesToRead, ifP); if (cmpBytesRead < bytesToRead) { if (feof(ifP)) pm_error("End of file reading row %u " "of compressed BMP raster.", row); else pm_error("Error reading BMP raster. Errno=%d (%s)", errno, strerror(errno)); } if (RLE4 && pixelsRead % 2 == 1) /* previous read ended odd */ nibbleAlign(&BMPraster[row][n-1], cnt); pixelsRead += cnt; totalBytesRead += cmpBytesRead + 2; } break; case END_OF_ROW: { if (cols == pixelsRead || cols + pixelsPerRowMargin == pixelsRead) { if (!lastrow) { *bytesReadP += totalBytesRead + 2; return; } else if (readRLEcode(ifP, NULL, NULL) == END_OF_BMP) { *bytesReadP += totalBytesRead +4; return; } else /* lastrow and END_OF_BITMAP not detected */ pm_error(err_decode, "End of bitmap not marked", row, pixelsRead ); } else pm_error(err_decode, "Premature end of row", row, pixelsRead); } break; case END_OF_BMP: { if (lastrow && (cols == pixelsRead || cols + pixelsPerRowMargin == pixelsRead)){ *bytesReadP += totalBytesRead + 2; return; } else pm_error(err_decode, "Premature end of bitmap", row, pixelsRead ); } break; case DELTA: { pm_error(err_decode, "Delta code in compressed BMP image. " "This program does not process deltas.", row, pixelsRead); } break; default: pm_error("Internal error processing RLE code in row %u", row); } } } static void BMPreadraster(FILE * const ifP, unsigned int const cols, unsigned int const rows, enum rowOrder const rowOrder, unsigned int const cBitCount, unsigned long int const compression, unsigned char *** const BMPrasterP, unsigned int * const bytesReadP) { unsigned int const bytesPerRow = (compression == COMP_RLE4) ? cols / 2 + 2 : (compression == COMP_RLE8) ? cols + 1 : ((cols * cBitCount + 31) / 32) * 4; /* A BMP raster row is a multiple of 4 bytes, padded on the right with don't cares. */ unsigned char ** BMPraster; BMPraster = allocBMPraster(rows, bytesPerRow); *bytesReadP = 0; /* row order BOTTOMUP is by far the most common case - the bottom line is first in the file, the top line last. We have never actually seen TOPDOWN, except in a Microsoft spec */ switch(compression){ case COMP_RGB: case COMP_BITFIELDS: { unsigned int i; for (i = 0; i < rows; ++i) readrow(ifP, rowOrder == TOPDOWN ? i : rows - i - 1, bytesPerRow, BMPraster, bytesReadP); } break; case COMP_RLE4: case COMP_RLE8: { unsigned int i; /* Read all rows except last */ for (i = 0; i < rows - 1; ++i){ readrowRLE(ifP, rowOrder == TOPDOWN ? i : rows - i - 1, cols, FALSE, compression, BMPraster, bytesReadP); } /* Read last row */ readrowRLE(ifP, rowOrder == TOPDOWN ? i : rows - i - 1, cols, TRUE, compression, BMPraster, bytesReadP); } break; default: pm_error("The BMP specifies a compression scheme we don't " "recognize. Code= %lu", compression); } *BMPrasterP = BMPraster; } static void reportHeader(struct bmpInfoHeader const header, unsigned int const offBits) { pm_message("BMP image header says:"); pm_message(" Class of BMP: %s", header.class == C_WIN ? "Windows" : header.class == C_OS2 ? "OS/2" : "???"); pm_message(" Width: %d pixels", header.cols); pm_message(" Height: %d pixels", header.rows); pm_message(" Depth: %d planes", header.cPlanes); pm_message(" Row order: %s", header.rowOrder == BOTTOMUP ? "bottom up" : "top down"); pm_message(" Byte offset of raster within file: %u", offBits); pm_message(" Bits per pixel in raster: %u", header.cBitCount); pm_message(" Compression: %s", header.compression == COMP_RGB ? "none" : header.compression == COMP_RLE4 ? "4 bit run-length coding" : header.compression == COMP_RLE8 ? "8 bit run-length coding" : header.compression == COMP_BITFIELDS ? "none" : header.compression == COMP_JPEG ? "JPEG (not supported)" : header.compression == COMP_PNG ? "PNG (not supported)" : "???"); pm_message(" Colors in color map: %u", header.cmapsize); } static void analyzeColors(xel const colormap[], unsigned int const cmapsize, xelval const maxval, bool * const grayPresentP, bool * const colorPresentP) { if (cmapsize == 0) { /* No colormap, and we're not about to search the entire raster, so we just assume it's full color */ *colorPresentP = TRUE; *grayPresentP = TRUE; } else { unsigned int i; *colorPresentP = FALSE; /* initial assumption */ *grayPresentP = FALSE; /* initial assumption */ for (i = 0; i < cmapsize; ++i) { if (PPM_ISGRAY(colormap[i])) { if (PPM_GETR(colormap[i]) != 0 && PPM_GETR(colormap[i]) != maxval) *grayPresentP = TRUE; } else *colorPresentP = TRUE; } } } static void warnIfOffBitsWrong(struct bmpInfoHeader const BMPheader, unsigned int const offBits) { if (offBits != BMPoffbits(BMPheader.class, BMPheader.cBitCount, BMPheader.cmapsize)) { pm_message("warning: the BMP header says the raster starts " "at offset %u bytes into the file (offbits), " "but that there are %u bytes of information before " "the raster. This inconsistency probably means the " "input file is not a legal BMP file and is unusable.", offBits, BMPoffbits(BMPheader.class, BMPheader.cBitCount, BMPheader.cmapsize)); } } static void readColorMap(FILE * const ifP, struct bmpInfoHeader const BMPheader, xel ** const colorMapP, unsigned int * const posP) { unsigned int bytesRead; BMPreadcolormap(ifP, BMPheader.class, colorMapP, BMPheader.cmapsize, &bytesRead); *posP += bytesRead; if (bytesRead != BMPlencolormap(BMPheader.class, BMPheader.cBitCount, BMPheader.cmapsize)) { pm_message("warning: %u-byte RGB table, expected %u bytes", bytesRead, BMPlencolormap(BMPheader.class, BMPheader.cBitCount, BMPheader.cmapsize)); } } static void readRaster(FILE * const ifP, struct bmpInfoHeader const BMPheader, unsigned char *** const BMPrasterP, unsigned int * const posP) { unsigned int bytesRead; BMPreadraster(ifP, BMPheader.cols, BMPheader.rows, BMPheader.rowOrder, BMPheader.cBitCount, BMPheader.compression, BMPrasterP, &bytesRead); *posP += bytesRead; } static void warnIfBadFileSize(struct bmpInfoHeader const BMPheader, unsigned int const pos) { unsigned int const expectedSize = BMPlenfileGen(BMPheader.class, BMPheader.cBitCount, BMPheader.cmapsize, BMPheader.cols, BMPheader.rows, BMPheader.imageSize, BMPheader.compression); if (pos != expectedSize) pm_message("warning: read %u bytes, expected to read %u bytes", pos, expectedSize); } static bool isValidBmpBpp(unsigned int const cBitCount) { switch (cBitCount) { case 1: case 2: case 4: case 8: case 16: case 24: case 32: return true; default: return false; } } static void readBmp(FILE * const ifP, unsigned char *** const BMPrasterP, int * const colsP, int * const rowsP, bool * const grayPresentP, bool * const colorPresentP, unsigned int * const cBitCountP, struct pixelformat * const pixelformatP, xel ** const colormapP, bool const verbose) { xel * colormap; /* malloc'ed */ unsigned int pos; /* Current byte position in the BMP file */ /* The following are all information from the BMP headers */ unsigned int offBits; /* Byte offset into file of raster */ struct bmpInfoHeader BMPheader; pos = 0; /* Starting at the beginning ... */ { unsigned int bytesRead; BMPreadfileheader(ifP, &bytesRead, &offBits); pos += bytesRead; } { unsigned int bytesRead; BMPreadinfoheader(ifP, &bytesRead, &BMPheader); if (verbose) pm_message("Read %u bytes of header", bytesRead); pos += bytesRead; } if (verbose) reportHeader(BMPheader, offBits); warnIfOffBitsWrong(BMPheader, offBits); readColorMap(ifP, BMPheader, &colormap, &pos); analyzeColors(colormap, BMPheader.cmapsize, bmpMaxval, grayPresentP, colorPresentP); readOffBytes(ifP, offBits - pos); pos = offBits; readRaster(ifP, BMPheader, BMPrasterP, &pos); warnIfBadFileSize(BMPheader, pos); if (fgetc(ifP) != EOF) pm_message("warning: some image data remains unread."); if (!isValidBmpBpp(BMPheader.cBitCount)) pm_error("Invalid BMP image: 'cBitCount' field of header " "(number of bits for each pixel in raster) is %u", BMPheader.cBitCount); *colsP = BMPheader.cols; *rowsP = BMPheader.rows; *cBitCountP = BMPheader.cBitCount; *pixelformatP = BMPheader.pixelformat; *colormapP = colormap; } static void writeRasterGen(unsigned char ** const BMPraster, int const cols, int const rows, int const format, unsigned int const cBitCount, struct pixelformat const pixelformat, xel const colormap[]) { /*---------------------------------------------------------------------------- Write the PNM raster to Standard Output, corresponding to the raw BMP raster BMPraster. Write the raster assuming the PNM image has dimensions 'cols' by 'rows' and format 'format', with maxval 255. The BMP image has 'cBitCount' bits per pixel, arranged in format 'pixelformat'. If the image is colormapped, colormap[] is the colormap (colormap[i] is the color with color index i). writeRasterPbm() is faster for a PBM image. -----------------------------------------------------------------------------*/ xel * xelrow; unsigned int row; xelrow = pnm_allocrow(cols); for (row = 0; row < rows; ++row) { convertRow(BMPraster[row], xelrow, cols, cBitCount, pixelformat, colormap); pnm_writepnmrow(stdout, xelrow, cols, bmpMaxval, format, FALSE); } pnm_freerow(xelrow); } static void writeRasterPbm(unsigned char ** const BMPraster, int const cols, int const rows, xel const colormap[]) { /*---------------------------------------------------------------------------- Write the PBM raster to Standard Output corresponding to the raw BMP raster BMPraster. Write the raster assuming the PBM image has dimensions 'cols' by 'rows'. The BMP image has 'cBitCount' bits per pixel, arranged in format 'pixelformat'. The image must be colormapped; colormap[] is the colormap (colormap[i] is the color with color index i). We cannot handle the abnormal case in which colormap[0] and colormap[1] have the same value (i.e. both white or both black.) We destroy *BMPraster as a side effect. -----------------------------------------------------------------------------*/ unsigned int const charBits = (sizeof(unsigned char) * 8); /* Number of bits in a character */ unsigned int const colChars = pbm_packed_bytes(cols); int row; enum colorFormat {BlackWhite, WhiteBlack}; enum colorFormat colorformat; if (PPM_GETR(colormap[0]) > 0) colorformat = WhiteBlack; else colorformat = BlackWhite; for (row=0; row < rows; ++row){ unsigned char * const bitrow = BMPraster[row]; if (colorformat == BlackWhite) { unsigned int i; for (i = 0; i < colChars; ++i) bitrow[i] = ~bitrow[i]; /* flip all pixels */ } if (cols % 8 > 0) { /* adjust final partial byte */ bitrow[colChars-1] >>= charBits - cols % charBits; bitrow[colChars-1] <<= charBits - cols % charBits; } pbm_writepbmrow_packed(stdout, bitrow, cols, FALSE); } } int main(int argc, char ** argv) { struct cmdline_info cmdline; FILE * ifP; int outputType; bool grayPresent, colorPresent; /* These tell whether the image contains shades of gray other than black and white and whether it has colors other than black, white, and gray. */ int cols, rows; unsigned char **BMPraster; /* The raster part of the BMP image, as a row x column array, with each element being a raw byte from the BMP raster. Note that BMPraster[0] is really Row 0 -- the top row of the image, even though the bottom row comes first in the BMP format. */ unsigned int cBitCount; /* Number of bits in BMP raster for each pixel */ struct pixelformat pixelformat; /* Format of the raster bits for a single pixel */ xel * colormap; /* Malloc'ed colormap (palette) from the BMP. Contents of map undefined if not a colormapped BMP. */ pnm_init(&argc, argv); parse_command_line(argc, argv, &cmdline); ifP = pm_openr(cmdline.input_filespec); if (streq(cmdline.input_filespec, "-")) ifname = "Standard Input"; else ifname = cmdline.input_filespec; readBmp(ifP, &BMPraster, &cols, &rows, &grayPresent, &colorPresent, &cBitCount, &pixelformat, &colormap, cmdline.verbose); pm_close(ifP); if (colorPresent) { outputType = PPM_TYPE; pm_message("WRITING PPM IMAGE"); } else if (grayPresent) { outputType = PGM_TYPE; pm_message("WRITING PGM IMAGE"); } else { outputType = PBM_TYPE; pm_message("WRITING PBM IMAGE"); } if (outputType == PBM_TYPE && cBitCount == 1){ pbm_writepbminit(stdout, cols, rows, FALSE); writeRasterPbm(BMPraster, cols, rows, colormap); } else { pnm_writepnminit(stdout, cols, rows, bmpMaxval, outputType, FALSE); writeRasterGen(BMPraster, cols, rows, outputType, cBitCount, pixelformat, colormap); } free(colormap); free(BMPraster); return 0; }