BMP图片转JPEG图片C程序源代码.docx

1、BMP图片转JPEG图片C程序源代码/ A BMP truecolor to JPEG encoder/ Copyright 1999 Cristian Cuturicu#include #include #include #include jtypes.h#include jglobals.h#include jtables.hvoid write_APP0info()/Nothing to overwrite for APP0info writeword(APP0info.marker); writeword(APP0info.length); writebyte(J); writebyt

2、e(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 ov

3、erwrite 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.IdC

4、b); 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; i64; i+) writebyte(DQTinfo.Ytablei); writebyte

5、(DQTinfo.QTCbinfo); for (i=0; i64; i+) writebyte(DQTinfo.Cbtablei);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; i64; i+) temp = (long) basic_tablei * scale_factor + 50L) / 100L; / limit the value

6、s to the valid range if (temp 255L) temp = 255L; newtablezigzagi = (BYTE) temp; void set_DQTinfo() BYTE scalefactor = 50;/ scalefactor controls the visual quality of the image / the smaller is the better image well get, and the smaller / compression well achieve DQTinfo.marker = 0xFFDB; DQTinfo.leng

7、th = 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

8、(i=0; i16; i+) writebyte(DHTinfo.YDC_nrcodesi); for (i=0; i12; i+) writebyte(DHTinfo.YDC_valuesi); writebyte(DHTinfo.HTYACinfo); for (i=0; i16; i+) writebyte(DHTinfo.YAC_nrcodesi); for (i=0; i162; i+) writebyte(DHTinfo.YAC_valuesi); writebyte(DHTinfo.HTCbDCinfo); for (i=0; i16; i+) writebyte(DHTinfo

9、.CbDC_nrcodesi); for (i=0; i12; i+) writebyte(DHTinfo.CbDC_valuesi); writebyte(DHTinfo.HTCbACinfo); for (i=0; i16; i+) writebyte(DHTinfo.CbAC_nrcodesi); for (i=0; i162; i+) writebyte(DHTinfo.CbAC_valuesi);void set_DHTinfo() BYTE i; / fill the DHTinfo structure get the values from the standard Huffma

10、n tables DHTinfo.marker = 0xFFC4; DHTinfo.length = 0x01A2; DHTinfo.HTYDCinfo = 0; for (i=0; i16; i+) DHTinfo.YDC_nrcodesi = std_dc_luminance_nrcodesi+1; for (i=0; i12; i+) DHTinfo.YDC_valuesi = std_dc_luminance_valuesi; DHTinfo.HTYACinfo = 0x10; for (i=0; i16; i+) DHTinfo.YAC_nrcodesi = std_ac_lumin

11、ance_nrcodesi+1; for (i=0; i162; i+) DHTinfo.YAC_valuesi = std_ac_luminance_valuesi; DHTinfo.HTCbDCinfo = 1; for (i=0; i16; i+) DHTinfo.CbDC_nrcodesi = std_dc_chrominance_nrcodesi+1; for (i=0; i12; i+) DHTinfo.CbDC_valuesi = std_dc_chrominance_valuesi; DHTinfo.HTCbACinfo = 0x11; for (i=0; i16; i+) D

12、HTinfo.CbAC_nrcodesi = std_ac_chrominance_nrcodesi+1; for (i=0; i162; i+) DHTinfo.CbAC_valuesi = std_ac_chrominance_valuesi;void write_SOSinfo()/Nothing to overwrite for SOSinfo writeword(SOSinfo.marker); writeword(SOSinfo.length); writebyte(SOSinfo.nrofcomponents); writebyte(SOSinfo.IdY); writebyte

13、(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 *)co

14、mment); writeword(length + 2); for (i=0; ilength; i+) writebyte(commenti);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 =0 value = bs.value; posval = bs.length - 1; while (posval = 0) if (v

15、alue & maskposval) bytenew |= maskbytepos; 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; BY

16、TE pos_in_table; WORD codevalue; codevalue = 0; pos_in_table = 0; for (k=1; k=16; k+) for (j=1; j=nrcodesk; j+) HTstd_tablepos_in_table.value = codevalue; HTstd_tablepos_in_table.length = k; pos_in_table+; codevalue+; codevalue = 1; void init_Huffman_tables() / Compute the Huffman tables used for en

17、coding 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_n

18、rcodes, std_ac_chrominance_values, CbAC_HT);void exitmessage(char *error_message) printf(%sn,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) exitmes

19、sage(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 n

20、umbers for (nr=nrlower; nrnrupper; nr+) categorynr = cat; bitcodenr.length = cat; bitcodenr.value = (WORD)nr; /Negative numbers for (nr=-(nrupper-1); nr=-nrlower; nr+) categorynr = cat; bitcodenr.length = cat; bitcodenr.value = (WORD)(nrupper-1+nr); nrlower = 1; nrupper = 1; void precalculate_YCbCr_

21、tables() WORD R,G,B; for (R=0; R256; R+) YRtabR = (SDWORD)(65536*0.299+0.5)*R; CbRtabR = (SDWORD)(65536*-0.16874+0.5)*R; CrRtabR = (SDWORD)(32768)*R; for (G=0; G256; G+) YGtabG = (SDWORD)(65536*0.587+0.5)*G; CbGtabG = (SDWORD)(65536*-0.33126+0.5)*G; CrGtabG = (SDWORD)(65536*-0.41869+0.5)*G; for (B=0

22、; B256; B+) YBtabB = (SDWORD)(65536*0.114+0.5)*B; CbBtabB = (SDWORD)(32768)*B; CrBtabB = (SDWORD)(65536*-0.08131+0.5)*B; / Using a bit modified form of the FDCT routine from IJGs C source:/ Forward DCT routine idea taken from Independent JPEG Groups C source for/ JPEG encoders/decoders/* For float A

23、A&N IDCT method, divisors are equal to quantization coefficients scaled by scalefactorrow*scalefactorcol, where scalefactor0 = 1 scalefactork = cos(k*PI/16) * sqrt(2) for k=1.7 We apply a further scale factor of 8. Whats actually stored is 1/divisor so that the inner loop can use a multiplication ra

24、ther than a division. */void prepare_quant_tables() double aanscalefactor8 = 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_Yi = (float) (1.0 / (double) DQTinfo.Ytablezigza

25、gi * aanscalefactorrow * aanscalefactorcol * 8.0); fdtbl_Cbi = (float) (1.0 / (double) DQTinfo.Cbtablezigzagi * aanscalefactorrow * aanscalefactorcol * 8.0); i+; void fdct_and_quantization(SBYTE *data, float *fdtbl, SWORD *outdata) float tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7; float tmp10, t

26、mp11, tmp12, tmp13; float z1, z2, z3, z4, z5, z11, z13; float *dataptr; float datafloat64; float temp; SBYTE ctr; BYTE i; for (i=0; i= 0; ctr-) tmp0 = dataptr0 + dataptr7; tmp7 = dataptr0 - dataptr7; tmp1 = dataptr1 + dataptr6; tmp6 = dataptr1 - dataptr6; tmp2 = dataptr2 + dataptr5; tmp5 = dataptr2

27、- dataptr5; tmp3 = dataptr3 + dataptr4; tmp4 = dataptr3 - dataptr4; /* Even part */ tmp10 = tmp0 + tmp3; /* phase 2 */ tmp13 = tmp0 - tmp3; tmp11 = tmp1 + tmp2; tmp12 = tmp1 - tmp2; dataptr0 = tmp10 + tmp11; /* phase 3 */ dataptr4 = tmp10 - tmp11; z1 = (tmp12 + tmp13) * (float) 0.707106781); /* c4 *

28、/ dataptr2 = tmp13 + z1; /* phase 5 */ dataptr6 = tmp13 - z1; /* Odd part */ tmp10 = tmp4 + tmp5; /* phase 2 */ tmp11 = tmp5 + tmp6; tmp12 = tmp6 + tmp7; /* The rotator is modified from fig 4-8 to avoid extra negations. */ z5 = (tmp10 - tmp12) * (float) 0.382683433); /* c6 */ z2 = (float) 0.541196100) * tmp10 + z5; /* c2-c6 */ z4 = (float) 1.306562965) * tmp12 + z5; /* c2+c6 */ z3 =