jpeg.rar_C语言JPEG_JPEG编码器

// A BMP truecolor to JPEG encoder // Copyright 1999 Cristi Cuturicu #include <stdio.h> #include <stdlib.h> #include <string.h> #include "jtypes.h" #include "jglobals.h" #include "jtables.h" void write_APP0info() //Nothing to overwrite for APP0info { writeword(APP0info.marker); writeword(APP0info.length); writebyte('J');writebyte('F');writebyte('I');writebyte('F');writebyte(0); writebyte(APP0info.versionhi);writebyte(APP0info.versionlo); writebyte(APP0info.xyunits); writeword(APP0info.xdensity);writeword(APP0info.ydensity); writebyte(APP0info.thumbnwidth);writebyte(APP0info.thumbnheight); } void write_SOF0info() // We should overwrite width and height { writeword(SOF0info.marker); writeword(SOF0info.length); writebyte(SOF0info.precision); writeword(SOF0info.height);writeword(SOF0info.width); writebyte(SOF0info.nrofcomponents); writebyte(SOF0info.IdY);writebyte(SOF0info.HVY);writebyte(SOF0info.QTY); writebyte(SOF0info.IdCb);writebyte(SOF0info.HVCb);writebyte(SOF0info.QTCb); writebyte(SOF0info.IdCr);writebyte(SOF0info.HVCr);writebyte(SOF0info.QTCr); } void write_DQTinfo() { BYTE i; writeword(DQTinfo.marker); writeword(DQTinfo.length); writebyte(DQTinfo.QTYinfo);for (i=0;i<64;i++) writebyte(DQTinfo.Ytable[i]); writebyte(DQTinfo.QTCbinfo);for (i=0;i<64;i++) writebyte(DQTinfo.Cbtable[i]); } void set_quant_table(BYTE *basic_table,BYTE scale_factor,BYTE *newtable) // Set quantization table and zigzag reorder it { BYTE i; long temp; for (i = 0; i < 64; i++) { temp = ((long) basic_table[i] * scale_factor + 50L) / 100L; /* limit the values to the valid range */ if (temp <= 0L) temp = 1L; if (temp > 255L) temp = 255L; /* limit to baseline range if requested */ newtable[zigzag[i]] = (WORD) temp; } } void set_DQTinfo() { BYTE scalefactor=50;// scalefactor controls the visual quality of the image // the smaller is, the better image we'll get, and the smaller // compression we'll achieve DQTinfo.marker=0xFFDB; DQTinfo.length=132; DQTinfo.QTYinfo=0; DQTinfo.QTCbinfo=1; set_quant_table(std_luminance_qt,scalefactor,DQTinfo.Ytable); set_quant_table(std_chrominance_qt,scalefactor,DQTinfo.Cbtable); } void write_DHTinfo() { BYTE i; writeword(DHTinfo.marker); writeword(DHTinfo.length); writebyte(DHTinfo.HTYDCinfo); for (i=0;i<16;i++) writebyte(DHTinfo.YDC_nrcodes[i]); for (i=0;i<=11;i++) writebyte(DHTinfo.YDC_values[i]); writebyte(DHTinfo.HTYACinfo); for (i=0;i<16;i++) writebyte(DHTinfo.YAC_nrcodes[i]); for (i=0;i<=161;i++) writebyte(DHTinfo.YAC_values[i]); writebyte(DHTinfo.HTCbDCinfo); for (i=0;i<16;i++) writebyte(DHTinfo.CbDC_nrcodes[i]); for (i=0;i<=11;i++) writebyte(DHTinfo.CbDC_values[i]); writebyte(DHTinfo.HTCbACinfo); for (i=0;i<16;i++) writebyte(DHTinfo.CbAC_nrcodes[i]); for (i=0;i<=161;i++) writebyte(DHTinfo.CbAC_values[i]); } void set_DHTinfo() { BYTE i; DHTinfo.marker=0xFFC4; DHTinfo.length=0x01A2; DHTinfo.HTYDCinfo=0; for (i=0;i<16;i++) DHTinfo.YDC_nrcodes[i]=std_dc_luminance_nrcodes[i+1]; for (i=0;i<=11;i++) DHTinfo.YDC_values[i]=std_dc_luminance_values[i]; DHTinfo.HTYACinfo=0x10; for (i=0;i<16;i++) DHTinfo.YAC_nrcodes[i]=std_ac_luminance_nrcodes[i+1]; for (i=0;i<=161;i++) DHTinfo.YAC_values[i]=std_ac_luminance_values[i]; DHTinfo.HTCbDCinfo=1; for (i=0;i<16;i++) DHTinfo.CbDC_nrcodes[i]=std_dc_chrominance_nrcodes[i+1]; for (i=0;i<=11;i++) DHTinfo.CbDC_values[i]=std_dc_chrominance_values[i]; DHTinfo.HTCbACinfo=0x11; for (i=0;i<16;i++) DHTinfo.CbAC_nrcodes[i]=std_ac_chrominance_nrcodes[i+1]; for (i=0;i<=161;i++) DHTinfo.CbAC_values[i]=std_ac_chrominance_values[i]; } void write_SOSinfo() //Nothing to overwrite for SOSinfo { writeword(SOSinfo.marker); writeword(SOSinfo.length); writebyte(SOSinfo.nrofcomponents); writebyte(SOSinfo.IdY);writebyte(SOSinfo.HTY); writebyte(SOSinfo.IdCb);writebyte(SOSinfo.HTCb); writebyte(SOSinfo.IdCr);writebyte(SOSinfo.HTCr); writebyte(SOSinfo.Ss);writebyte(SOSinfo.Se);writebyte(SOSinfo.Bf); } void write_comment(BYTE *comment) { WORD i,length; writeword(0xFFFE); //The COM marker length=strlen((const char *)comment); writeword(length+2); for (i=0;i<length;i++) writebyte(comment[i]); } void writebits(bitstring bs) // A portable version; it should be done in assembler { WORD value; SBYTE posval;//bit position in the bitstring we read, should be<=15 and >=0 value=bs.value; posval=bs.length-1; while (posval>=0) { if (value & mask[posval]) bytenew|=mask[bytepos]; posval--;bytepos--; if (bytepos<0) { if (bytenew==0xFF) {writebyte(0xFF);writebyte(0);} else {writebyte(bytenew);} bytepos=7;bytenew=0; } } } void compute_Huffman_table(BYTE *nrcodes,BYTE *std_table,bitstring *HT) { BYTE k,j; BYTE pos_in_table; WORD codevalue; codevalue=0; pos_in_table=0; for (k=1;k<=16;k++) { for (j=1;j<=nrcodes[k];j++) {HT[std_table[pos_in_table]].value=codevalue; HT[std_table[pos_in_table]].length=k; pos_in_table++; codevalue++; } codevalue*=2; } } void init_Huffman_tables() { compute_Huffman_table(std_dc_luminance_nrcodes,std_dc_luminance_values,YDC_HT); compute_Huffman_table(std_dc_chrominance_nrcodes,std_dc_chrominance_values,CbDC_HT); compute_Huffman_table(std_ac_luminance_nrcodes,std_ac_luminance_values,YAC_HT); compute_Huffman_table(std_ac_chrominance_nrcodes,std_ac_chrominance_values,CbAC_HT); } void exitmessage(char *error_message) { printf("%s\n",error_message);exit(EXIT_FAILURE); } void set_numbers_category_and_bitcode() { SDWORD nr; SDWORD nrlower,nrupper; BYTE cat,value; category_alloc=(BYTE *)malloc(65535*sizeof(BYTE)); if (category_alloc==NULL) exitmessage("Not enough memory."); category=category_alloc+32767; //allow negative subscripts bitcode_alloc=(bitstring *)malloc(65535*sizeof(bitstring)); if (bitcode_alloc==NULL) exitmessage("Not enough memory."); bitcode=bitcode_alloc+32767; nrlower=1;nrupper=2; for (cat=1;cat<=15;cat++) { //Positive numbers for (nr=nrlower;nr<nrupper;nr++) { category[nr]=cat; bitcode[nr].length=cat; bitcode[nr].value=(WORD)nr; } //Negative numbers for (nr=-(nrupper-1);nr<=-nrlower;nr++) { category[nr]=cat; bitcode[nr].length=cat; bitcode[nr].value=(WORD)(nrupper-1+nr); } nrlower<<=1; nrupper<<=1; } } void precalculate_YCbCr_tables() { WORD R,G,B; for (R=0;R<=255;R++) {YRtab[R]=(SDWORD)(65536*0.299+0.5)*R; CbRtab[R]=(SDWORD)(65536*-0.16874+0.5)*R; CrRtab[R]=(SDWORD)(32768)*R; } for (G=0;G<=255;G++) {YGtab[G]=(SDWORD)(65536*0.587+0.5)*G; CbGtab[G]=(SDWORD)(65536*-0.33126+0.5)*G; CrGtab[G]=(SDWORD)(65536*-0.41869+0.5)*G; } for (B=0;B<=255;B++) {YBtab[B]=(SDWORD)(65536*0.114+0.5)*B; CbBtab[B]=(SDWORD)(32768)*B; CrBtab[B]=(SDWORD)(65536*-0.08131+0.5)*B; } } // Using a bit modified form of the FDCT routine from IJG's C source: // Forward DCT routine idea taken from Independent JPEG Group's C source for // JPEG encoders/decoders /* For float AA&N IDCT method, divisors are equal to quantization coefficients scaled by scalefactor[row]*scalefactor[col], where scalefactor[0] = 1 scalefactor[k] = cos(k*PI/16) * sqrt(2) for k=1..7 We apply a further scale factor of 8. What's actually stored is 1/divisor so that the inner loop can use a multiplication rather than a division. */ void prepare_quant_tables() { double aanscalefactor[8] = {1.0, 1.387039845, 1.306562965, 1.175875602, 1.0, 0.785694958, 0.541196100, 0.275899379}; BYTE row, col; BYTE i = 0; for (row = 0; row < 8; row++) { for (col = 0; col < 8; col++) { fdtbl_Y[i] = (float) (1.0 / ((double) DQTinfo.Ytable[zigzag[i]] * aanscalefactor[