bmp转jpeg源码

// A BMP truecolor to JPEG encoder // Copyright 1999 Cristian 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; newtable[zigzag[i]] = (BYTE) 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<12; i++) writebyte(DHTinfo.YDC_values[i]); writebyte(DHTinfo.HTYACinfo); for (i=0; i<16; i++) writebyte(DHTinfo.YAC_nrcodes[i]); for (i=0; i<162; i++) writebyte(DHTinfo.YAC_values[i]); writebyte(DHTinfo.HTCbDCinfo); for (i=0; i<16; i++) writebyte(DHTinfo.CbDC_nrcodes[i]); for (i=0; i<12; i++) writebyte(DHTinfo.CbDC_values[i]); writebyte(DHTinfo.HTCbACinfo); for (i=0; i<16; i++) writebyte(DHTinfo.CbAC_nrcodes[i]); for (i=0; i<162; i++) writebyte(DHTinfo.CbAC_values[i]); } void set_DHTinfo() { BYTE i; // fill the DHTinfo structure [get the values from the standard Huffman tables] 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<12; 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<162; 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<12; 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<162; 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) { // write it if (bytenew == 0xFF) { // special case writebyte(0xFF); writebyte(0); } else writebyte(bytenew); // reinit 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 <<= 1; } } void init_Huffman_tables() { // Compute the Huffman tables used for encoding compute_Huffman_table(std_dc_luminance_nrcodes, std_dc_luminance_values, YDC_HT); compute_Huffman_table(std_ac_luminance_nrcodes, std_ac_luminance_values, YAC_HT); compute_Huffman_table(std_dc_chrominance_nrcodes, std_dc_chrominance_values, CbDC_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; category_alloc = (BYTE *)malloc(65535*sizeof(BYTE)); if (category_alloc == NULL) exitmessage("Not enough memory."); //allow negative subscripts category = category_alloc + 32767; 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<256; 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<256; 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<256; 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.