paul@manray.sgi.com (Paul Haeberli) (10/03/89)
/* * togif - * Convert an IRIS image to GIF format. Converts b/w and * color images to 8 bit per pixel GIF format. Color images * are dithered with a 4 by 4 dither matrix. GIF image files * may be uuencoded, and sent over the network. * * Paul Haeberli @ Silicon Graphics - 1989 * * To compile use: * * cc -I/usr/include/gl togif.c -o togif -limage * */ #include "image.h" #define MAXXSIZE 4096 #define MAXCOLORS 256 short rbuf[MAXXSIZE]; short gbuf[MAXXSIZE]; short bbuf[MAXXSIZE]; short obuf[MAXXSIZE]; int rmap[MAXCOLORS]; int gmap[MAXCOLORS]; int bmap[MAXCOLORS]; int iscolor, currow; IMAGE *iimage; int getgifpix(x,y) int x, y; { if(iscolor) { if(currow!= y) { getrow(iimage,rbuf,iimage->ysize-1-y,0); getrow(iimage,gbuf,iimage->ysize-1-y,1); getrow(iimage,bbuf,iimage->ysize-1-y,2); ditherrow(rbuf,gbuf,bbuf,obuf,iimage->xsize,y); currow = y; } return obuf[x]; } else { if(currow!= y) { getrow(iimage,rbuf,iimage->ysize-1-y,0); currow = y; } return rbuf[x]; } } main( argc, argv ) int argc; char *argv[]; { FILE *of; int xsize, ysize; int i, bpp; int r, g, b; if(argc<2) { fprintf(stderr,"usage: togif image.rgb image.gif\n"); exit(1); } iimage = iopen(argv[1],"r"); if(!iimage) { fprintf(stderr,"togif: can't open input image [%s]\n",argv[1]); exit(1); } xsize = iimage->xsize; ysize = iimage->ysize; if(iimage->zsize>=3) iscolor = 1; else iscolor = 0; of = fopen(argv[2],"w"); if(!of) { fprintf(stderr,"togif: can't open out image [%s]\n",argv[2]); exit(1); } if(iscolor) { for(i=0; i<MAXCOLORS; i++) { r = (i>>0)&0x7; g = (i>>3)&0x7; b = (i>>6)&0x3; rmap[i] = (255*r)/7; gmap[i] = (255*g)/7; bmap[i] = (255*b)/3; } } else { for(i=0; i<MAXCOLORS; i++) { rmap[i] = i; gmap[i] = i; bmap[i] = i; } } bpp = 8; currow = -1; GIFEncode(of,xsize,ysize,0,0,bpp,rmap,gmap,bmap,getgifpix); exit(0); } /* * dithering code follows * * */ #define XSIZE 4 #define YSIZE 4 #define TOTAL (XSIZE*YSIZE) #define WRAPY(y) ((y)%YSIZE) #define WRAPX(x) ((x)%XSIZE) static short dithmat[YSIZE][XSIZE] = { 0, 8, 2, 10, 12, 4, 14, 6, 3, 11, 1, 9, 15, 7, 13, 5, }; short **rtab; short **gtab; short **btab; short **makedittab(levels,mult,add) int levels, mult, add; { register int val; register int nshades; register int i, j, k; register int matval, tabval; short **tab; nshades = XSIZE*YSIZE*(levels-1)+1; tab = (short **)malloc(YSIZE*sizeof(short *)); for(j=0; j<YSIZE; j++) { tab[j] = (short *)malloc(XSIZE*256*sizeof(short)); for(i=0; i<XSIZE; i++ ) { matval = dithmat[i][j]; for(k=0; k<256; k++) { val = (nshades*k)/255; if(val==nshades) val = nshades-1; if((val%TOTAL)>matval) tabval = (val/TOTAL)+1; else tabval = (val/TOTAL); tabval *= mult; tabval += add; tab[j][256*i+k] = tabval; } } } return tab; } ditherrow(r,g,b,wp,n,y) unsigned short *r, *g, *b; short *wp; int n, y; { short *rbase; short *gbase; short *bbase; if(!rtab) { rtab = makedittab(8,1,0); gtab = makedittab(8,8,0); btab = makedittab(4,64,0); } rbase = rtab[WRAPY(y)]; gbase = gtab[WRAPY(y)]; bbase = btab[WRAPY(y)]; while(n) { if(n>=XSIZE) { *wp++ = rbase[*r++ + 0] + gbase[*g++ + 0] + bbase[*b++ + 0]; *wp++ = rbase[*r++ + 256] + gbase[*g++ + 256] + bbase[*b++ + 256]; *wp++ = rbase[*r++ + 512] + gbase[*g++ + 512] + bbase[*b++ + 512]; *wp++ = rbase[*r++ + 768] + gbase[*g++ + 768] + bbase[*b++ + 768]; n -= XSIZE; } else { *wp++ = rbase[*r++] + gbase[*g++] + bbase[*b++]; rbase += 256; gbase += 256; bbase += 256; n--; } } } /* * SCARY GIF code follows . . . . sorry. * * Based on GIFENCOD by David Rowley <mgardi@watdscu.waterloo.edu>.A * Lempel-Zim compression based on "compress". * */ /***************************************************************************** * * GIFENCODE.C - GIF Image compression interface * * GIFEncode( FName, GHeight, GWidth, GInterlace, Background, * BitsPerPixel, Red, Green, Blue, GetPixel ) * *****************************************************************************/ typedef int (* ifunptr)(); #define TRUE 1 #define FALSE 0 int Width, Height; int curx, cury; long CountDown; int Pass = 0; int Interlace; /* * Bump the 'curx' and 'cury' to point to the next pixel */ BumpPixel() { curx++; if( curx == Width ) { curx = 0; if( !Interlace ) { cury++; } else { switch( Pass ) { case 0: cury += 8; if( cury >= Height ) { Pass++; cury = 4; } break; case 1: cury += 8; if( cury >= Height ) { Pass++; cury = 2; } break; case 2: cury += 4; if( cury >= Height ) { Pass++; cury = 1; } break; case 3: cury += 2; break; } } } } /* * Return the next pixel from the image */ GIFNextPixel( getpixel ) ifunptr getpixel; { int r; if( CountDown == 0 ) return EOF; CountDown--; r = (*getpixel)( curx, cury ); BumpPixel(); return r; } /* * public GIFEncode */ GIFEncode( fp, GWidth, GHeight, GInterlace, Background, BitsPerPixel, Red, Green, Blue, GetPixel ) FILE *fp; int GWidth, GHeight; int GInterlace; int Background; int BitsPerPixel; int Red[], Green[], Blue[]; ifunptr GetPixel; { int B; int RWidth, RHeight; int LeftOfs, TopOfs; int Resolution; int ColorMapSize; int InitCodeSize; int i; Interlace = GInterlace; ColorMapSize = 1 << BitsPerPixel; RWidth = Width = GWidth; RHeight = Height = GHeight; LeftOfs = TopOfs = 0; Resolution = BitsPerPixel; CountDown = (long)Width * (long)Height; Pass = 0; if( BitsPerPixel <= 1 ) InitCodeSize = 2; else InitCodeSize = BitsPerPixel; curx = cury = 0; fwrite( "GIF87a", 1, 6, fp ); Putword( RWidth, fp ); Putword( RHeight, fp ); B = 0x80; /* Yes, there is a color map */ B |= (Resolution - 1) << 5; B |= (BitsPerPixel - 1); fputc( B, fp ); fputc( Background, fp ); fputc( 0, fp ); for( i=0; i<ColorMapSize; i++ ) { fputc( Red[i], fp ); fputc( Green[i], fp ); fputc( Blue[i], fp ); } fputc( ',', fp ); Putword( LeftOfs, fp ); Putword( TopOfs, fp ); Putword( Width, fp ); Putword( Height, fp ); if( Interlace ) fputc( 0x40, fp ); else fputc( 0x00, fp ); fputc( InitCodeSize, fp ); compress( InitCodeSize+1, fp, GetPixel ); fputc( 0, fp ); fputc( ';', fp ); fclose( fp ); } /* * Write out a word to the GIF file */ Putword( w, fp ) int w; FILE *fp; { fputc( w & 0xff, fp ); fputc( (w/256) & 0xff, fp ); } /*************************************************************************** * * GIFCOMPR.C - GIF Image compression routines * * Lempel-Ziv compression based on 'compress'. GIF modifications by * David Rowley (mgardi@watdcsu.waterloo.edu) * ***************************************************************************/ #define BITS 12 #define HSIZE 5003 /* 80% occupancy */ /* * a code_int must be able to hold 2**BITS values of type int, and also -1 */ typedef int code_int; typedef long int count_int; typedef unsigned char char_type; /* * * GIF Image compression - modified 'compress' * * Based on: compress.c - File compression ala IEEE Computer, June 1984. * * By Authors: Spencer W. Thomas (decvax!harpo!utah-cs!utah-gr!thomas) * Jim McKie (decvax!mcvax!jim) * Steve Davies (decvax!vax135!petsd!peora!srd) * Ken Turkowski (decvax!decwrl!turtlevax!ken) * James A. Woods (decvax!ihnp4!ames!jaw) * Joe Orost (decvax!vax135!petsd!joe) * */ #include <ctype.h> #define ARGVAL() (*++(*argv) || (--argc && *++argv)) int n_bits; /* number of bits/code */ int maxbits = BITS; /* user settable max # bits/code */ code_int maxcode; /* maximum code, given n_bits */ code_int maxmaxcode = (code_int)1 << BITS; /* should NEVER generate this code */ # define MAXCODE(n_bits) (((code_int) 1 << (n_bits)) - 1) count_int htab [HSIZE]; unsigned short codetab [HSIZE]; #define HashTabOf(i) htab[i] #define CodeTabOf(i) codetab[i] code_int hsize = HSIZE; /* for dynamic table sizing */ count_int fsize; /* * To save much memory, we overlay the table used by compress() with those * used by decompress(). The tab_prefix table is the same size and type * as the codetab. The tab_suffix table needs 2**BITS characters. We * get this from the beginning of htab. The output stack uses the rest * of htab, and contains characters. There is plenty of room for any * possible stack (stack used to be 8000 characters). */ #define tab_prefixof(i) CodeTabOf(i) #define tab_suffixof(i) ((char_type *)(htab))[i] #define de_stack ((char_type *)&tab_suffixof((code_int)1<<BITS)) code_int free_ent = 0; /* first unused entry */ int exit_stat = 0; /* * block compression parameters -- after all codes are used up, * and compression rate changes, start over. */ int clear_flg = 0; int offset; long int in_count = 1; /* length of input */ long int out_count = 0; /* # of codes output (for debugging) */ /* * compress stdin to stdout * * Algorithm: use open addressing double hashing (no chaining) on the * prefix code / next character combination. We do a variant of Knuth's * algorithm D (vol. 3, sec. 6.4) along with G. Knott's relatively-prime * secondary probe. Here, the modular division first probe is gives way * to a faster exclusive-or manipulation. Also do block compression with * an adaptive reset, whereby the code table is cleared when the compression * ratio decreases, but after the table fills. The variable-length output * codes are re-sized at this point, and a special CLEAR code is generated * for the decompressor. Late addition: construct the table according to * file size for noticeable speed improvement on small files. Please direct * questions about this implementation to ames!jaw. */ int g_init_bits; FILE *g_outfile; int ClearCode; int EOFCode; compress( init_bits, outfile, ReadValue ) int init_bits; FILE *outfile; ifunptr ReadValue; { register long fcode; register code_int i = 0; register int c; register code_int ent; register code_int disp; register code_int hsize_reg; register int hshift; /* * Set up the globals: g_init_bits - initial number of bits * g_outfile - pointer to output file */ g_init_bits = init_bits; g_outfile = outfile; /* * Set up the necessary values */ offset = 0; out_count = 0; clear_flg = 0; in_count = 1; maxcode = MAXCODE(n_bits = g_init_bits); ClearCode = (1 << (init_bits - 1)); EOFCode = ClearCode + 1; free_ent = ClearCode + 2; char_init(); ent = GIFNextPixel( ReadValue ); hshift = 0; for ( fcode = (long) hsize; fcode < 65536L; fcode *= 2L ) hshift++; hshift = 8 - hshift; /* set hash code range bound */ hsize_reg = hsize; cl_hash( (count_int) hsize_reg); /* clear hash table */ output( (code_int)ClearCode ); while ( (c = GIFNextPixel( ReadValue )) != EOF ) { in_count++; fcode = (long) (((long) c << maxbits) + ent); /* i = (((code_int)c << hshift) ~ ent); /* xor hashing */ i = (((code_int)c << hshift) ^ ent); /* xor hashing */ if ( HashTabOf (i) == fcode ) { ent = CodeTabOf (i); continue; } else if ( (long)HashTabOf (i) < 0 ) /* empty slot */ goto nomatch; disp = hsize_reg - i; /* secondary hash (after G. Knott) */ if ( i == 0 ) disp = 1; probe: if ( (i -= disp) < 0 ) i += hsize_reg; if ( HashTabOf (i) == fcode ) { ent = CodeTabOf (i); continue; } if ( (long)HashTabOf (i) > 0 ) goto probe; nomatch: output ( (code_int) ent ); out_count++; ent = c; if ( free_ent < maxmaxcode ) { CodeTabOf (i) = free_ent++; /* code -> hashtable */ HashTabOf (i) = fcode; } else cl_block(); } /* * Put out the final code. */ output( (code_int)ent ); out_count++; output( (code_int) EOFCode ); return; } /***************************************************************** * TAG( output ) * * Output the given code. * Inputs: * code: A n_bits-bit integer. If == -1, then EOF. This assumes * that n_bits =< (long)wordsize - 1. * Outputs: * Outputs code to the file. * Assumptions: * Chars are 8 bits long. * Algorithm: * Maintain a BITS character long buffer (so that 8 codes will * fit in it exactly). Use the VAX insv instruction to insert each * code in turn. When the buffer fills up empty it and start over. */ unsigned long cur_accum = 0; int cur_bits = 0; unsigned long masks[] = { 0x0000, 0x0001, 0x0003, 0x0007, 0x000F, 0x001F, 0x003F, 0x007F, 0x00FF, 0x01FF, 0x03FF, 0x07FF, 0x0FFF, 0x1FFF, 0x3FFF, 0x7FFF, 0xFFFF }; output( code ) code_int code; { cur_accum &= masks[ cur_bits ]; if( cur_bits > 0 ) cur_accum |= ((long)code << cur_bits); else cur_accum = code; cur_bits += n_bits; while( cur_bits >= 8 ) { char_out( (unsigned int)(cur_accum & 0xff) ); cur_accum >>= 8; cur_bits -= 8; } /* * If the next entry is going to be too big for the code size, * then increase it, if possible. */ if ( free_ent > maxcode || clear_flg ) { if( clear_flg ) { maxcode = MAXCODE (n_bits = g_init_bits); clear_flg = 0; } else { n_bits++; if ( n_bits == maxbits ) maxcode = maxmaxcode; else maxcode = MAXCODE(n_bits); } } if( code == EOFCode ) { /* * At EOF, write the rest of the buffer. */ while( cur_bits > 0 ) { char_out( (unsigned int)(cur_accum & 0xff) ); cur_accum >>= 8; cur_bits -= 8; } flush_char(); fflush( g_outfile ); if( ferror( g_outfile ) ) writeerr(); } } /* * Clear out the hash table */ cl_block () /* table clear for block compress */ { cl_hash ( (count_int) hsize ); free_ent = ClearCode + 2; clear_flg = 1; output( (code_int)ClearCode ); } cl_hash(hsize) /* reset code table */ register count_int hsize; { register count_int *htab_p = htab+hsize; register long i; register long m1 = -1; i = hsize - 16; do { /* might use Sys V memset(3) here */ *(htab_p-16) = m1; *(htab_p-15) = m1; *(htab_p-14) = m1; *(htab_p-13) = m1; *(htab_p-12) = m1; *(htab_p-11) = m1; *(htab_p-10) = m1; *(htab_p-9) = m1; *(htab_p-8) = m1; *(htab_p-7) = m1; *(htab_p-6) = m1; *(htab_p-5) = m1; *(htab_p-4) = m1; *(htab_p-3) = m1; *(htab_p-2) = m1; *(htab_p-1) = m1; htab_p -= 16; } while ((i -= 16) >= 0); for ( i += 16; i > 0; i-- ) *--htab_p = m1; } writeerr() { printf( "error writing output file\n" ); exit(1); } /****************************************************************************** * * GIF Specific routines * ******************************************************************************/ /* * Number of characters so far in this 'packet' */ int a_count; /* * Set up the 'byte output' routine */ char_init() { a_count = 0; } /* * Define the storage for the packet accumulator */ char accum[ 256 ]; /* * Add a character to the end of the current packet, and if it is 254 * characters, flush the packet to disk. */ char_out( c ) int c; { accum[ a_count++ ] = c; if( a_count >= 254 ) flush_char(); } /* * Flush the packet to disk, and reset the accumulator */ flush_char() { if( a_count > 0 ) { fputc( a_count, g_outfile ); fwrite( accum, 1, a_count, g_outfile ); a_count = 0; } }