{ >> I'm searching for the description of the structure of the >> BMP-format And also of the PCX-format... First the BMP format; Bitmap-File Formats Windows bitmap files are stored in a device-independent bitmap (DIB) format that allows Windows to display the bitmap on any type of display device. The term "device independent" means that the bitmap specifies pixel color in a form independent of the method used by a display to represent color. The default filename extension of a Windows DIB file is .BMP. Bitmap-File Structures Each bitmap file contains a bitmap-file header, a bitmap-information header, a color table, and an array of bytes that defines the bitmap bits. The bitmap-file header contains information about the type, size, and layout of a device-independent bitmap file. The header is defined as a TBITMAPFILEHEADER structure. The bitmap-information header, defined as a TBITMAPINFOHEADER structure, specifies the dimensions, compression type, and color format for the bitmap. The color table, defined as an array of TRGBQUAD structures, contains as many elements as there are colors in the bitmap. The color table is not present for bitmaps with 24 color bits because each pixel is represented by 24-bit red-green-blue (RGB) values in the actual bitmap data area. The colors in the table should appear in order of importance. This helps a display driver render a bitmap on a device that cannot display as many colors as there are in the bitmap. If the DIB is in Windows version 3.0 or later format, the driver can use the biClrImportant member of the TBITMAPINFOHEADER structure to determine which colors are important. The TBITMAPINFO structure can be used to represent a combined bitmap-information header and color table. The bitmap bits, immediately following the color table, consist of an array of BYTE values representing consecutive rows, or "scan lines," of the bitmap. Each scan line consists of consecutive bytes representing the pixels in the scan line, in left-to-right order. The number of bytes representing a scan line depends on the color format and the width, in pixels, of the bitmap. If necessary, a scan line must be zero-padded to end on a 32-bit boundary. However, segment boundaries can appear anywhere in the bitmap. The scan lines in the bitmap are stored from bottom up. This means that the first byte in the array represents the pixels in the lower-left corner of the bitmap and the last byte represents the pixels in the upper-right corner. The biBitCount member of the TBITMAPINFOHEADER structure determines the number of bits that define each pixel and the maximum number of colors in the bitmap. These members can have any of the following values: Value Meaning 1 Bitmap is monochrome and the color table contains two entries. Each bit in the bitmap array represents a pixel. If the bit is clear, the pixel is displayed with the color of the first entry in the color table. If the bit is set, the pixel has the color of the second entry in the table. 4 Bitmap has a maximum of 16 colors. Each pixel in the bitmap is represented by a 4-bit index into the color table. For example, if the first byte in the bitmap is 0x1F, the byte represents two pixels. The first pixel contains the color in the second table entry, and the second pixel contains the color in the sixteenth table entry. 8 Bitmap has a maximum of 256 colors. Each pixel in the bitmap is represented by a 1-byte index into the color table. For example, if the first byte in the bitmap is 0x1F, the first pixel has the color of the thirty-second table entry. 24 Bitmap has a maximum of 2^24 colors. The bmiColors (or bmciColors) member is NULL, and each 3-byte sequence in the bitmap array represents the relative intensities of red, green, and blue, respectively, for a pixel. The biClrUsed member of the TBITMAPINFOHEADER structure specifies the number of color indexes in the color table actually used by the bitmap. If the biClrUsed member is set to zero, the bitmap uses the maximum number of colors corresponding to the value of the biBitCount member. An alternative form of bitmap file uses the BITMAPCOREINFO, TBITMAPCOREHEADER, and TRGBTRIPLE structures. Bitmap Compression Windows versions 3.0 and later support run-length encoded (RLE) formats for compressing bitmaps that use 4 bits per pixel and 8 bits per pixel. Compression reduces the disk and memory storage required for a bitmap. Compression of 8-Bits-per-Pixel Bitmaps When the biCompression member of the TBITMAPINFOHEADER structure is set to BI_RLE8, the DIB is compressed using a run-length encoded format for a 256-color bitmap. This format uses two modes: encoded mode and absolute mode. Both modes can occur anywhere throughout a single bitmap. Encoded Mode A unit of information in encoded mode consists of two bytes. The first byte specifies the number of consecutive pixels to be drawn using the color index contained in the second byte. The first byte of the pair can be set to zero to indicate an escape that denotes the end of a line, the end of the bitmap, or a delta. The interpretation of the escape depends on the value of the second byte of the pair, which must be in the range 0x00 through 0x02. Following are the meanings of the escape values that can be used in the second byte: Second byte Meaning 0 End of line. 1 End of bitmap. 2 Delta. The two bytes following the escape contain unsigned values indicating the horizontal and vertical offsets of the next pixel from the current position. Absolute Mode Absolute mode is signaled by the first byte in the pair being set to zero and the second byte to a value between 0x03 and 0xFF. The second byte represents the number of bytes that follow, each of which contains the color index of a single pixel. Each run must be aligned on a word boundary. Following is an example of an 8-bit RLE bitmap (the two-digit hexadecimal values in the second column represent a color index for a single pixel): Compressed data Expanded data 03 04 04 04 04 05 06 06 06 06 06 06 00 03 45 56 67 00 45 56 67 02 78 78 78 00 02 05 01 Move 5 right and 1 down 02 78 78 78 00 00 End of line 09 1E 1E 1E 1E 1E 1E 1E 1E 1E 1E 00 01 End of RLE bitmap Compression of 4-Bits-per-Pixel Bitmaps When the biCompression member of the TBITMAPINFOHEADER structure is set to BI_RLE4, the DIB is compressed using a run-length encoded format for a 16-color bitmap. This format uses two modes: encoded mode and absolute mode. Encoded Mode A unit of information in encoded mode consists of two bytes. The first byte of the pair contains the number of pixels to be drawn using the color indexes in the second byte. The second byte contains two color indexes, one in its high-order nibble (that is, its low-order 4 bits) and one in its low-order nibble. The first pixel is drawn using the color specified by the high-order nibble, the second is drawn using the color in the low-order nibble, the third is drawn with the color in the high-order nibble, and so on, until all the pixels specified by the first byte have been drawn. The first byte of the pair can be set to zero to indicate an escape that denotes the end of a line, the end of the bitmap, or a delta. The interpretation of the escape depends on the value of the second byte of the pair. In encoded mode, the second byte has a value in the range 0x00 through 0x02. The meaning of these values is the same as for a DIB with 8 bits per pixel. Absolute Mode In absolute mode, the first byte contains zero, the second byte contains the number of color indexes that follow, and subsequent bytes contain color indexes in their high- and low-order nibbles, one color index for each pixel. Each run must be aligned on a word boundary. Following is an example of a 4-bit RLE bitmap (the one-digit hexadecimal values in the second column represent a color index for a single pixel): Compressed data Expanded data 03 04 0 4 0 05 06 0 6 0 6 0 00 06 45 56 67 00 4 5 5 6 6 7 04 78 7 8 7 8 00 02 05 01 Move 5 right and 1 down 04 78 7 8 7 8 00 00 End of line 09 1E 1 E 1 E 1 E 1 E 1 00 01 End of RLE bitmap Bitmap Example The following example is a text dump of a 16-color bitmap (4 bits per pixel): Win3DIBFile BitmapFileHeader Type 19778 Size 3118 Reserved1 0 Reserved2 0 OffsetBits 118 TBITMAPINFOHeader Size 40 Width 80 Height 75 Planes 1 BitCount 4 Compression 0 SizeImage 3000 XPelsPerMeter 0 YPelsPerMeter 0 ColorsUsed 16 ColorsImportant 16 Win3ColorTable Blue Green Red Unused [00000000] 84 252 84 0 [00000001] 252 252 84 0 [00000002] 84 84 252 0 [00000003] 252 84 252 0 [00000004] 84 252 252 0 [00000005] 252 252 252 0 [00000006] 0 0 0 0 [00000007] 168 0 0 0 [00000008] 0 168 0 0 [00000009] 168 168 0 0 [0000000A] 0 0 168 0 [0000000B] 168 0 168 0 [0000000C] 0 168 168 0 [0000000D] 168 168 168 0 [0000000E] 84 84 84 0 [0000000F] 252 84 84 0 Image . . Bitmap data . Now the PCX format; Introduction This booklet was designed to aid developers and users in understanding the technical aspects of the .PCX file format and the use of FRIEZE. Any comments, questions or suggestions about this booklet should be sent to: ZSoft Corporation Technical Services ATTN: Code Librarian 450 Franklin Rd. Suite 100 Marietta, GA 30067 Technical Reference Manual information compiled by: Dave Steier & Dean Ansley Revision 5 To down load additional information and the source for a complete Turbo Pascal program to show .PCX files on a CGA/EGA/VGA graphics display, call our BBS at (404)427-1045. You may use a 9600 baud modem or a 2400 baud standard modem. Your modem should be set for 8 data bits, 1 stop bit, and NO parity. Image File (.PCX) Format If you have technical questions on the format, please do not call technical support. ZSoft provides this document as a courtesy to its users and developers. It is not the function of Technical Support to provide programming assistance. If something is not clear, leave a message on our BBS, Compuserve, or write us a letter at the above address. The information in this section will be useful if you want to write a program to read or write PCX files (images). If you want to write a special case program for one particular image format you should be able to produce something that runs twice as fast as "Load from..." in PC Paintbrush. Image files used by PC Paintbrush product family and FRIEZE (those with a .PCX extension) begin with a 128 byte header. Usually you can ignore this header, since your images will probably all have the same resolution. If you want to process different resolutions or colors, you will need to interpret the header correctly. The remainder of the image file consists of encoded graphic data. The encoding method is a simple byte oriented run-length technique. We reserve the right to change this method to improve space efficiency. When more than one color plane is stored in the file, each line of the image is stored by color plane (generally ordered red, green, blue, intensity), As shown below. Scan line 0: RRR... (Plane 0) GGG... (Plane 1) BBB... (Plane 2) III... (Plane 3) Scan line 1: RRR... GGG... BBB... III... (etc.) The encoding method is: FOR each byte, X, read from the file IF the top two bits of X are 1's then count = 6 lowest bits of X data = next byte following X ELSE count = 1 data = X Since the overhead this technique requires is, on average, 25% of the non-repeating data and is at least offset whenever bytes are repeated, the file storage savings are usually considerable. ZSoft .PCX FILE HEADER FORMAT Byte Item Size Description/Comments 0 Manufacturer 1 Constant Flag, 10 = ZSoft .pcx 1 Version 1 Version information 0 = Version 2.5 of PC Paintbrush 2 = Version 2.8 w/palette information 3 = Version 2.8 w/o palette information 4 = PC Paintbrush for Windows(Plus for Windows uses Ver 5) 5 = Version 3.0 and > of PC Paintbrush and PC Paintbrush +, includes Publisher's Paintbrush . Includes 24-bit .PCX files 2 Encoding 1 1 = .PCX run length encoding 3 BitsPerPixel 1 Number of bits to represent a pixel (per Plane) - 1, 2, 4, or 8 4 Window 8 Image Dimensions: Xmin,Ymin,Xmax,Ymax 12 HDpi 2 Horizontal Resolution of image in DPI* 14 VDpi 2 Vertical Resolution of image in DPI* 16 Colormap 48 Color palette setting, see text 64 Reserved 1 Should be set to 0. 65 NPlanes 1 Number of color planes 66 BytesPerLine 2 Number of bytes to allocate for a scanline plane. MUST be an EVEN number. Do NOT calculate from Xmax-Xmin. 68 PaletteInfo 2 How to interpret palette- 1 = Color/BW, 2 = Grayscale (ignored in PB IV/ IV +) 70 HscreenSize 2 Horizontal screen size in pixels. New field found only in PB IV/IV Plus 72 VscreenSize 2 Vertical screen size in pixels. New field found only in PB IV/IV Plus 74 Filler 54 Blank to fill out 128 byte header. Set all bytes to 0 NOTES: All sizes are measured in BYTES. All variables of SIZE 2 are integers. *HDpi and VDpi represent the Horizontal and Vertical resolutions which the image was created (either printer or scanner); i.e. an image which was scanned might have 300 and 300 in each of these fields. Decoding .PCX Files First, find the pixel dimensions of the image by calculating [XSIZE = Xmax - Xmin + 1] and [YSIZE = Ymax - Ymin + 1]. Then calculate how many bytes are required to hold one complete uncompressed scan line: TotalBytes = NPlanes * BytesPerLine Note that since there are always an even number of bytes per scan line, there will probably be unused data at the end of each scan line. TotalBytes shows how much storage must be available to decode each scan line, including any blank area on the right side of the image. You can now begin decoding the first scan line - read the first byte of data from the file. If the top two bits are set, the remaining six bits in the byte show how many times to duplicate the next byte in the file. If the top two bits are not set, the first byte is the data itself, with a count of one. Continue decoding the rest of the line. Keep a running subtotal of how many bytes are moved and duplicated into the output buffer. When the subtotal equals TotalBytes, the scan line is complete. There should always be a decoding break at the end of each scan line. But there will not be a decoding break at the end of each plane within each scan line. When the scan line is completed, there may be extra blank data at the end of each plane within the scan line. Use the XSIZE and YSIZE values to find where the valid image data is. If the data is multi-plane, BytesPerLine shows where each plane ends within the scan line. Continue decoding the remainder of the scan lines (do not just read to end-of-file). There may be additional data after the end of the image (palette, etc.) Palette Information Description EGA/VGA 16 Color Palette Information The palette information is stored in one of two different formats. In standard RGB format (IBM EGA, IBM VGA) the data is stored as 16 triples. Each triple is a 3 byte quantity of Red, Green, Blue values. The values can range from 0-255, so some interpretation may be necessary. On an IBM EGA, for example, there are 4 possible levels of RGB for each color. Since 256/4 = 64, the following is a list of the settings and levels: Setting Level 0-63 0 64-127 1 128-192 2 193-254 3 24-Bit .PCX Files 24 bit images are stored as version 5 or above as 8 bit, 3 plane images. 24 bit images do not contain a palette. Bit planes are ordered as lines of red, green, blue in that order. VGA 256 Color Palette Information ZSoft has recently added the capability to store palettes containing more than 16 colors in the .PCX image file. The 256 color palette is formatted and treated the same as the 16 color palette, except that it is substantially longer. The palette (number of colors x 3 bytes in length) is appended to the end of the .PCX file, and is preceded by a 12 decimal. Since the VGA device expects a palette value to be 0-63 instead of 0-255, you need to divide the values read in the palette by 4. To access a 256 color palette: First, check the version number in the header; if it contains a 5 there is a palette. Second, read to the end of the file and count back 769 bytes. The value you find should be a 12 decimal, showing the presence of a 256 color palette. CGA Color Palette Information NOTE: This is no longer supported for PC Paintbrush IV/IV Plus. For a standard IBM CGA board, the palette settings are a bit more complex. Only the first byte of the triple is used. The first triple has a valid first byte which represents the background color. To find the background, take the (unsigned) byte value and divide by 16. This will give a result between 0-15, hence the background color. The second triple has a valid first byte, which represents the foreground palette. PC Paintbrush supports 8 possible CGA palettes, so when the foreground setting is encoded between 0 and 255, there are 8 ranges of numbers and the divisor is 32. CGA Color Map Header Byte #16 Background color is determined in the upper four bits. Header Byte #19 Only upper 3 bits are used, lower 5 bits are ignored. The first three bits that are used are ordered C, P, I. These bits are interpreted as follows: c: color burst enable - 0 = color; 1 = monochrome p: palette - 0 = yellow; 1 = white i: intensity - 0 = dim; 1 = bright PC Paintbrush Bitmap Character Format NOTE: This format is for PC Paintbrush (up to Vers 3.7) and PC Paintbrush Plus (up to Vers 1.65) The bitmap character fonts are stored in a particularly simple format. The format of these characters is as follows: Header font width byte 0xA0 + character width (in pixels) font height byte character height (in pixels) Character Width Table char widths (256 bytes) each char's width + 1 pixel of kerning Character Images (remainder of the file) starts at char 0 (Null) The characters are stored in ASCII order and as many as 256 may be provided. Each character is left justified in the character block, all characters take up the same number of bytes. Bytes are organized as N strings, where each string is one scan line of the character. For example, each character in a 5x7 font requires 7 bytes. A 9x14 font uses 28 bytes per character (stored two bytes per scan line in 14 sets of 2 byte packets). Custom fonts may be any size up to the current maximum of 10K bytes allowed for a font file. There is a maximum of 4 bytes per scan line.Sample "C" Routines The following is a simple set of C subroutines to read data from a .PCX file. /* This procedure reads one encoded block from the image file and stores a count and data byte. Return result: 0 = valid data stored, EOF = out of data in file */ encget(pbyt, pcnt, fid) int *pbyt; /* where to place data */ int *pcnt; /* where to place count */ FILE *fid; /* image file handle */ { int i; *pcnt = 1; /* assume a "run" length of one */ if (EOF == (i = getc(fid))) return (EOF); if (0xC0 == (0xC0 & i)) { *pcnt = 0x3F & i; if (EOF == (i = getc(fid))) return (EOF); } *pbyt = i; return (0); } /* Here's a program fragment using encget. This reads an entire file and stores it in a (large) buffer, pointed to by the variable "bufr". "fp" is the file pointer for the image */ int i; long l, lsize; lsize = (long )hdr.BytesPerLine * hdr.Nplanes * (1 + hdr.Ymax - hdr.Ymin); for (l = 0; l < lsize; ) /* increment by cnt below */ { if (EOF == encget(&chr, &cnt, fp)) break; for (i = 0; i < cnt; i++) *bufr++ = chr; l += cnt; } The following is a set of C subroutines to write data to a .PCX file. /* Subroutine for writing an encoded byte pair (or single byte if it doesn't encode) to a file. It returns the count of bytes written, 0 if error */ encput(byt, cnt, fid) unsigned char byt, cnt; FILE *fid; { if (cnt) { if ((cnt == 1) && (0xC0 != (0xC0 & byt))) { if (EOF == putc((int )byt, fid)) return(0); /* disk write error (probably full) */ return(1); } else { if (EOF == putc((int )0xC0 | cnt, fid)) return (0); /* disk write error */ if (EOF == putc((int )byt, fid)) return (0); /* disk write error */ return (2); } } return (0); }/* This subroutine encodes one scanline and writes it to a file. It returns number of bytes written into outBuff, 0 if failed. */ encLine(inBuff, inLen, fp) unsigned char *inBuff; /* pointer to scanline data */ int inLen; /* length of raw scanline in bytes */ FILE *fp; /* file to be written to */ { unsigned char this, last; int srcIndex, i; register int total; register unsigned char runCount; /* max single runlength is 63 */ total = 0; runCount = 1; last = *(inBuff); /* Find the pixel dimensions of the image by calculating [XSIZE = Xmax - Xmin + 1] and [YSIZE = Ymax - Ymin + 1]. Then calculate how many bytes are in a "run" */ for (srcIndex = 1; srcIndex < inLen; srcIndex++) { this = *(++inBuff); if (this == last) /* There is a "run" in the data, encode it */ { runCount++; if (runCount == 63) { if (! (i = encput(last, runCount, fp))) return (0); total += i; runCount = 0; } } else /* No "run" - this != last */ { if (runCount) { if (! (i = encput(last, runCount, fp))) return(0); total += i; } last = this; runCount = 1; } } /* endloop */ if (runCount) /* finish up */ { if (! (i = encput(last, runCount, fp))) return (0); return (total + i); } return (total); } FRIEZE Technical Information General FRIEZE Information FRIEZE is a memory-resident utility that allows you to capture and save graphic images from other programs. You can then bring these images into PC Paintbrush for editing and enhancement. FRIEZE 7.10 and later can be removed from memory (this can return you up to 90K of DOS RAM, depending on your configuration). To remove FRIEZE from memory, change directories to your paintbrush directory and type the word "FRIEZE". 7.00 and Later FRIEZE The FRIEZE command line format is: FRIEZE {PD} {Xn[aarr]} {flags} {video} {hres} {vres} {vnum} Where: {PD} Printer driver filename (without the .PDV extension) {Xn[aarr]} X=S for Serial Printer, P for Parallel Printer, D for disk file. (file is always named FRIEZE.PRN) n = port number aa = Two digit hex code for which return bits cause an abort (optional) rr = Two digit hex code for which return bits cause a retry (optional) NOTE: These codes represent return values from serial or parallel port BIOS calls. For values see and IBM BIOS reference (such as Ray Duncan's Advanced MS-DOS Programming). {flags}Four digit hex code First Digit controls Length Flag Second Digit controls Width Flag Third Digit controls Mode Flag Fourth Digit controls BIOS Flag 0 - None 1 - Dual Monitor Present 2 - Use internal (true) B/W palette for dithering 2 color images 4 - Capture palette along with screen IN VGA ONLY Frieze 8.08 & up ONLY) NOTE: The length, width and mode flags are printer driver specific. See PRINTERS.DAT on disk 1 (or Setup Disk) for correct use. In general width flag of 1 means wide carriage, and 0 means standard width. Length flag of 0 and mode flag of 0 means use default printer driver settings. If you need to use more than one BIOS flag option, add the needed flag values