因需要，用到了，bmp2jpg壓縮，在pudn上看到一個源碼，寫的不錯，故記錄與此，如有盜用之嫌，還請包涵與指出。
headers.h
#define BYTE unsigned char
#define SBYTE signed char
#define SWORD signed short int
#define WORD unsigned short int
#define DWORD unsigned long int
#define SDWORD signed long int
static struct APP0infotype {
WORD marker;// = 0xFFE0
WORD length; // = 16 for usual JPEG, no thumbnail
BYTE JFIFsignature[5]; // = "JFIF",'\0'
BYTE versionhi; // 1
BYTE versionlo; // 1
BYTE xyunits; // 0 = no units, normal density
WORD xdensity; // 1
WORD ydensity; // 1
BYTE thumbnwidth; // 0
BYTE thumbnheight; // 0
} APP0info={0xFFE0,16,'J','F','I','F',0,1,1,0,1,1,0,0};
static struct SOF0infotype {
WORD marker; // = 0xFFC0
WORD length; // = 17 for a truecolor YCbCr JPG
BYTE precision ;// Should be 8: 8 bits/sample
WORD height ;
WORD width;
BYTE nrofcomponents;//Should be 3: We encode a truecolor JPG
BYTE IdY; // = 1
BYTE HVY; // sampling factors for Y (bit 0-3 vert., 4-7 hor.)
BYTE QTY; // Quantization Table number for Y = 0
BYTE IdCb; // = 2
BYTE HVCb;
BYTE QTCb; // 1
BYTE IdCr; // = 3
BYTE HVCr;
BYTE QTCr; // Normally equal to QTCb = 1
} SOF0info = { 0xFFC0,17,8,0,0,3,1,0x11,0,2,0x11,1,3,0x11,1};
// Default sampling factors are 1,1 for every image component: No downsampling
static struct DQTinfotype {
WORD marker; // = 0xFFDB
WORD length; // = 132
BYTE QTYinfo;// = 0: bit 0..3: number of QT = 0 (table for Y)
// bit 4..7: precision of QT, 0 = 8 bit
BYTE Ytable[64];
BYTE QTCbinfo; // = 1 (quantization table for Cb,Cr}
BYTE Cbtable[64];
} DQTinfo;
// Ytable from DQTinfo should be equal to a scaled and zizag reordered version
// of the table which can be found in "tables.h": std_luminance_qt
// Cbtable , similar = std_chrominance_qt
// We'll init them in the program using set_DQTinfo function
static struct DHTinfotype {
WORD marker; // = 0xFFC4
WORD length; //0x01A2
BYTE HTYDCinfo; // bit 0..3: number of HT (0..3), for Y =0
//bit 4 :type of HT, 0 = DC table,1 = AC table
//bit 5..7: not used, must be 0
BYTE YDC_nrcodes[16]; //at index i = nr of codes with length i
BYTE YDC_values[12];
BYTE HTYACinfo; // = 0x10
BYTE YAC_nrcodes[16];
BYTE YAC_values[162];//we'll use the standard Huffman tables
BYTE HTCbDCinfo; // = 1
BYTE CbDC_nrcodes[16];
BYTE CbDC_values[12];
BYTE HTCbACinfo; // = 0x11
BYTE CbAC_nrcodes[16];
BYTE CbAC_values[162];
} DHTinfo;
static struct SOSinfotype {
WORD marker; // = 0xFFDA
WORD length; // = 12
BYTE nrofcomponents; // Should be 3: truecolor JPG
BYTE IdY; //1
BYTE HTY; //0 // bits 0..3: AC table (0..3)
// bits 4..7: DC table (0..3)
BYTE IdCb; //2
BYTE HTCb; //0x11
BYTE IdCr; //3
BYTE HTCr; //0x11
BYTE Ss,Se,Bf; // not interesting, they should be 0,63,0
} SOSinfo={0xFFDA,12,3,1,0,2,0x11,3,0x11,0,0x3F,0};
typedef struct { BYTE B,G,R; } colorRGB;
typedef struct { BYTE length;
WORD value;} bitstring;
#define Y(R,G,B) ((BYTE)( (YRtab[(R)]+YGtab[(G)]+YBtab[(B)])>>16 ) - 128)
#define Cb(R,G,B) ((BYTE)( (CbRtab[(R)]+CbGtab[(G)]+CbBtab[(B)])>>16 ) )
#define Cr(R,G,B) ((BYTE)( (CrRtab[(R)]+CrGtab[(G)]+CrBtab[(B)])>>16 ) )
#define writebyte(b) fputc((b),fp_jpeg_stream)
#define writeword(w) writebyte((w)/256);writebyte((w)%256);
static BYTE zigzag[64]={ 0, 1, 5, 6,14,15,27,28,
2, 4, 7,13,16,26,29,42,
3, 8,12,17,25,30,41,43,
9,11,18,24,31,40,44,53,
10,19,23,32,39,45,52,54,
20,22,33,38,46,51,55,60,
21,34,37,47,50,56,59,61,
35,36,48,49,57,58,62,63 };
/* These are the sample quantization tables given in JPEG spec section K.1.
The spec says that the values given produce "good" quality, and
when divided by 2, "very good" quality.*/
static BYTE std_luminance_qt[64] = {
16, 11, 10, 16, 24, 40, 51, 61,
12, 12, 14, 19, 26, 58, 60, 55,
14, 13, 16, 24, 40, 57, 69, 56,
14, 17, 22, 29, 51, 87, 80, 62,
18, 22, 37, 56, 68, 109, 103, 77,
24, 35, 55, 64, 81, 104, 113, 92,
49, 64, 78, 87, 103, 121, 120, 101,
72, 92, 95, 98, 112, 100, 103, 99
};
static BYTE std_chrominance_qt[64] = {
17, 18, 24, 47, 99, 99, 99, 99,
18, 21, 26, 66, 99, 99, 99, 99,
24, 26, 56, 99, 99, 99, 99, 99,
47, 66, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99,
99, 99, 99, 99, 99, 99, 99, 99
};
// Standard Huffman tables (cf. JPEG standard section K.3) */
static BYTE std_dc_luminance_nrcodes[17]={0,0,1,5,1,1,1,1,1,1,0,0,0,0,0,0,0};
static BYTE std_dc_luminance_values[12]={0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
static BYTE std_dc_chrominance_nrcodes[17]={0,0,3,1,1,1,1,1,1,1,1,1,0,0,0,0,0};
static BYTE std_dc_chrominance_values[12]={0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
static BYTE std_ac_luminance_nrcodes[17]={0,0,2,1,3,3,2,4,3,5,5,4,4,0,0,1,0x7d };
static BYTE std_ac_luminance_values[162]= {
0x01, 0x02, 0x03, 0x00, 0x04, 0x11, 0x05, 0x12,
0x21, 0x31, 0x41, 0x06, 0x13, 0x51, 0x61, 0x07,
0x22, 0x71, 0x14, 0x32, 0x81, 0x91, 0xa1, 0x08,
0x23, 0x42, 0xb1, 0xc1, 0x15, 0x52, 0xd1, 0xf0,
0x24, 0x33, 0x62, 0x72, 0x82, 0x09, 0x0a, 0x16,
0x17, 0x18, 0x19, 0x1a, 0x25, 0x26, 0x27, 0x28,
0x29, 0x2a, 0x34, 0x35, 0x36, 0x37, 0x38, 0x39,
0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48, 0x49,
0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58, 0x59,
0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68, 0x69,
0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78, 0x79,
0x7a, 0x83, 0x84, 0x85, 0x86, 0x87, 0x88, 0x89,
0x8a, 0x92, 0x93, 0x94, 0x95, 0x96, 0x97, 0x98,
0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5, 0xa6, 0xa7,
0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4, 0xb5, 0xb6,
0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3, 0xc4, 0xc5,
0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2, 0xd3, 0xd4,
0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda, 0xe1, 0xe2,
0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9, 0xea,
0xf1, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
0xf9, 0xfa };
static BYTE std_ac_chrominance_nrcodes[17]={0,0,2,1,2,4,4,3,4,7,5,4,4,0,1,2,0x77};
static BYTE std_ac_chrominance_values[162]={
0x00, 0x01, 0x02, 0x03, 0x11, 0x04, 0x05, 0x21,
0x31, 0x06, 0x12, 0x41, 0x51, 0x07, 0x61, 0x71,
0x13, 0x22, 0x32, 0x81, 0x08, 0x14, 0x42, 0x91,
0xa1, 0xb1, 0xc1, 0x09, 0x23, 0x33, 0x52, 0xf0,
0x15, 0x62, 0x72, 0xd1, 0x0a, 0x16, 0x24, 0x34,
0xe1, 0x25, 0xf1, 0x17, 0x18, 0x19, 0x1a, 0x26,
0x27, 0x28, 0x29, 0x2a, 0x35, 0x36, 0x37, 0x38,
0x39, 0x3a, 0x43, 0x44, 0x45, 0x46, 0x47, 0x48,
0x49, 0x4a, 0x53, 0x54, 0x55, 0x56, 0x57, 0x58,
0x59, 0x5a, 0x63, 0x64, 0x65, 0x66, 0x67, 0x68,
0x69, 0x6a, 0x73, 0x74, 0x75, 0x76, 0x77, 0x78,
0x79, 0x7a, 0x82, 0x83, 0x84, 0x85, 0x86, 0x87,
0x88, 0x89, 0x8a, 0x92, 0x93, 0x94, 0x95, 0x96,
0x97, 0x98, 0x99, 0x9a, 0xa2, 0xa3, 0xa4, 0xa5,
0xa6, 0xa7, 0xa8, 0xa9, 0xaa, 0xb2, 0xb3, 0xb4,
0xb5, 0xb6, 0xb7, 0xb8, 0xb9, 0xba, 0xc2, 0xc3,
0xc4, 0xc5, 0xc6, 0xc7, 0xc8, 0xc9, 0xca, 0xd2,
0xd3, 0xd4, 0xd5, 0xd6, 0xd7, 0xd8, 0xd9, 0xda,
0xe2, 0xe3, 0xe4, 0xe5, 0xe6, 0xe7, 0xe8, 0xe9,
0xea, 0xf2, 0xf3, 0xf4, 0xf5, 0xf6, 0xf7, 0xf8,
0xf9, 0xfa };
static BYTE bytenew=0; // The byte that will be written in the JPG file
static SBYTE bytepos=7; //bit position in the byte we write (bytenew)
//should be<=7 and >=0
static WORD mask[16]={1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768};
// The Huffman tables we'll use:
static bitstring YDC_HT[12];
static bitstring CbDC_HT[12];
static bitstring YAC_HT[256];
static bitstring CbAC_HT[256];
static BYTE *category_alloc;
static BYTE *category; //Here we'll keep the category of the numbers in range: -32767..32767
static bitstring *bitcode_alloc;
static bitstring *bitcode; // their bitcoded representation
//Precalculated tables for a faster YCbCr->RGB transformation
// We use a SDWORD table because we'll scale values by 2^16 and work with integers
static SDWORD YRtab[256],YGtab[256],YBtab[256];
static SDWORD CbRtab[256],CbGtab[256],CbBtab[256];
static SDWORD CrRtab[256],CrGtab[256],CrBtab[256];
static float fdtbl_Y[64];
static float fdtbl_Cb[64]; //the same with the fdtbl_Cr[64]
colorRGB *RGB_buffer; //image to be encoded
WORD Ximage,Yimage;// image dimensions divisible by 8
static SBYTE YDU[64]; // This is the Data Unit of Y after YCbCr->RGB transformation
static SBYTE CbDU[64];
static SBYTE CrDU[64];
static SWORD DU_DCT[64]; // Current DU (after DCT and quantization) which we'll zigzag
static SWORD DU[64]; //zigzag reordered DU which will be Huffman coded
FILE *fp_jpeg_stream;
bmp2jpg.c
/* Hi there, the archived file you got should contain the C source of my JPEG encoder.
Legal stuff
-----------
You get this source for free so absolutely no warranty is provided with it.
Use it at your own risk.
Description
-----------
The principles of designing my JPEG encoder were mainly clarity and portability.
So it's made in plain ANSI C. That's why it worked, compiled on a lot of C
compilers. Here is the list: WATCOM C 10.0, DJGPP 2.0, VISUAL C 6.0,
GCC under Linux,Solaris,VMS, FreeBSD.
And its simplicity makes it fast enough I think.
The FDCT routine is taken with minor modifications from Independent JPEG Group's
JPEG software . So don't ask me details about that.
The rest it's done by me.
The program should give the same results on any C compiler which provides at least
256 kb of free memory. I needed that for the precalculated bitcode (3*64k) and
category (64k) arrays , not to mention the memory needed for the truecolor BMP.
Since it's made to encode a truecolor BMP into a JPG file, I think that it
should be no problem for you to figure out how to modify the C source in order
to use it with any RGB image you want to compress (small enough to fit into
your memory) .
A note: The JPG format I used is a personal choice:
The sampling factors are 1:1 for simplicity reasons, the Huffman tables
are those given in the standard (so it's not optimized for that particular
image you want to encode), etc.
I coded only what I needed from a JPEG encoder. Probably it could have
more advanced features.
There are a lot of other JPG formats (markers in another order, another markers),
so don't ask me why a JPG file not encoded with this encoder has a different
format (different locations , another markers...).
Though not necessary, an email saying at least 'THANKS ' would be nice if
you find it useful.
You are free to use/modify it in a your production(s) but it would be nice to say
in your documentation that you used ideas/routines from the JPEG encoder made by
Cristi Cuturicu.
For more info you can check the doc "jpgalgo.txt" or the JPEG standard.
Both can be found at www.wotsit.org
If you have questions regarding this encoder, want to improve it, maybe report bugs,
here is my email address:
[email protected]
or [email protected] */
//
//THE SOURCE !
/
//
//END OF HEADERS
//
// 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"
#include "headers.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[row] * aanscalefactor[col] * 8.0));
fdtbl_Cb[i] = (float) (1.0 / ((double) DQTinfo.Cbtable[zigzag[i]] *
aanscalefactor[row] * aanscalefactor[col] * 8.0));
i++;
}
}
}
void fdct_and_quantization(SBYTE *data,float *fdtbl,SWORD *outdata)
{
float tmp0, tmp1, tmp2, tmp3, tmp4, tmp5, tmp6, tmp7;
float tmp10, tmp11, tmp12, tmp13;
float z1, z2, z3, z4, z5, z11, z13;
float *dataptr;
float datafloat[64];
float temp;
SBYTE ctr;
BYTE i;
for (i=0;i<64;i++) datafloat[i]=data[i];
/* Pass 1: process rows. */
dataptr=datafloat;
for (ctr = 7; ctr >= 0; ctr--) {
tmp0 = dataptr[0] + dataptr[7];
tmp7 = dataptr[0] - dataptr[7];
tmp1 = dataptr[1] + dataptr[6];
tmp6 = dataptr[1] - dataptr[6];
tmp2 = dataptr[2] + dataptr[5];
tmp5 = dataptr[2] - dataptr[5];
tmp3 = dataptr[3] + dataptr[4];
tmp4 = dataptr[3] - dataptr[4];
/* Even part */
tmp10 = tmp0 + tmp3; /* phase 2 */
tmp13 = tmp0 - tmp3;
tmp11 = tmp1 + tmp2;
tmp12 = tmp1 - tmp2;
dataptr[0] = tmp10 + tmp11; /* phase 3 */
dataptr[4] = tmp10 - tmp11;
z1 = (tmp12 + tmp13) * ((float) 0.707106781); /* c4 */
dataptr[2] = tmp13 + z1; /* phase 5 */
dataptr[6] = 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 = tmp11 * ((float) 0.707106781); /* c4 */
z11 = tmp7 + z3; /* phase 5 */
z13 = tmp7 - z3;
dataptr[5] = z13 + z2; /* phase 6 */
dataptr[3] = z13 - z2;
dataptr[1] = z11 + z4;
dataptr[7] = z11 - z4;
dataptr += 8; /* advance pointer to next row */
}
/* Pass 2: process columns. */
dataptr = datafloat;
for (ctr = 7; ctr >= 0; ctr--) {
tmp0 = dataptr[0] + dataptr[56];
tmp7 = dataptr[0] - dataptr[56];
tmp1 = dataptr[8] + dataptr[48];
tmp6 = dataptr[8] - dataptr[48];
tmp2 = dataptr[16] + dataptr[40];
tmp5 = dataptr[16] - dataptr[40];
tmp3 = dataptr[24] + dataptr[32];
tmp4 = dataptr[24] - dataptr[32];
/* Even part */
tmp10 = tmp0 + tmp3; /* phase 2 */
tmp13 = tmp0 - tmp3;
tmp11 = tmp1 + tmp2;
tmp12 = tmp1 - tmp2;
dataptr[0] = tmp10 + tmp11; /* phase 3 */
dataptr[32] = tmp10 - tmp11;
z1 = (tmp12 + tmp13) * ((float) 0.707106781); /* c4 */
dataptr[16] = tmp13 + z1; /* phase 5 */
dataptr[48] = 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 = tmp11 * ((float) 0.707106781); /* c4 */
z11 = tmp7 + z3; /* phase 5 */
z13 = tmp7 - z3;
dataptr[40] = z13 + z2; /* phase 6 */
dataptr[24] = z13 - z2;
dataptr[8] = z11 + z4;
dataptr[56] = z11 - z4;
dataptr++; /* advance pointer to next column */
}
// Quantize/descale the coefficients, and store into output array
for (i = 0; i < 64; i++) {
/* Apply the quantization and scaling factor */
temp = datafloat[i] * fdtbl[i];
/* Round to nearest integer.
Since C does not specify the direction of rounding for negative
quotients, we have to force the dividend positive for portability.
The maximum coefficient size is +-16K (for 12-bit data), so this
code should work for either 16-bit or 32-bit ints.
*/
outdata[i] = (SWORD) ((SWORD)(temp + 16384.5) - 16384);
}
}
void process_DU(SBYTE *ComponentDU,float *fdtbl,SWORD *DC,
bitstring *HTDC,bitstring *HTAC)
{
bitstring EOB=HTAC[0x00];
bitstring M16zeroes=HTAC[0xF0];
BYTE i;
BYTE startpos;
BYTE end0pos;
BYTE nrzeroes;
BYTE nrmarker;
SWORD Diff;
fdct_and_quantization(ComponentDU,fdtbl,DU_DCT);
//zigzag reorder
for (i=0;i<=63;i++) DU[zigzag[i]]=DU_DCT[i];
Diff=DU[0]-*DC;
*DC=DU[0];
//Encode DC
if (Diff==0) writebits(HTDC[0]); //Diff might be 0
else {writebits(HTDC[category[Diff]]);
writebits(bitcode[Diff]);
}
//Encode ACs
for (end0pos=63;(end0pos>0)&&(DU[end0pos]==0);end0pos--) ;
//end0pos = first element in reverse order !=0
if (end0pos==0) {writebits(EOB);return;}
i=1;
while (i<=end0pos)
{
startpos=i;
for (; (DU[i]==0)&&(i<=end0pos);i++) ;
nrzeroes=i-startpos;
if (nrzeroes>=16) {
for (nrmarker=1;nrmarker<=nrzeroes/16;nrmarker++) writebits(M16zeroes);
nrzeroes=nrzeroes%16;
}
writebits(HTAC[nrzeroes*16+category[DU[i]]]);writebits(bitcode[DU[i]]);
i++;
}
if (end0pos!=63) writebits(EOB);
}
void load_data_units_from_RGB_buffer(WORD xpos,WORD ypos)
{
BYTE x,y;
BYTE pos=0;
DWORD location;
BYTE R,G,B;
location=ypos*Ximage+xpos;
for (y=0;y<8;y++)
{
for (x=0;x<8;x++)
{
R=RGB_buffer[location].R;G=RGB_buffer[location].G;B=RGB_buffer[location].B;
YDU[pos]=Y(R,G,B);
CbDU[pos]=Cb(R,G,B);
CrDU[pos]=Cr(R,G,B);
location++;pos++;
}
location+=Ximage-8;
}
}
void main_encoder()
{
SWORD DCY=0,DCCb=0,DCCr=0; //DC coefficients used for differential encoding
WORD xpos,ypos;
for (ypos=0;ypos<Yimage;ypos+=8)
for (xpos=0;xpos<Ximage;xpos+=8)
{
load_data_units_from_RGB_buffer(xpos,ypos);
process_DU(YDU,fdtbl_Y,&DCY,YDC_HT,YAC_HT);
process_DU(CbDU,fdtbl_Cb,&DCCb,CbDC_HT,CbAC_HT);
process_DU(CrDU,fdtbl_Cb,&DCCr,CbDC_HT,CbAC_HT);
}
}
void load_bitmap(char *bitmap_name, WORD *Ximage_original, WORD *Yimage_original)
{
WORD Xdiv8,Ydiv8;
BYTE nr_fillingbytes;//The number of the filling bytes in the BMP file
// (the dimension in bytes of a BMP line on the disk is divisible by 4)
colorRGB lastcolor;
WORD column;
BYTE TMPBUF[256];
WORD nrline_up,nrline_dn,nrline;
WORD dimline;
colorRGB *tmpline;
FILE *fp_bitmap=fopen(bitmap_name,"rb");
if (fp_bitmap==NULL) exitmessage("Cannot open bitmap file.File not found ?");
if (fread(TMPBUF,1,54,fp_bitmap)!=54)
exitmessage("Need a truecolor BMP to encode.");
if ((TMPBUF[0]!='B')||(TMPBUF[1]!='M')||(TMPBUF[28]!=24))
exitmessage("Need a truecolor BMP to encode.");
Ximage=(WORD)TMPBUF[19]*256+TMPBUF[18];Yimage=(WORD)TMPBUF[23]*256+TMPBUF[22];
*Ximage_original=Ximage;*Yimage_original=Yimage; //Keep the old dimensions
// of the image
if (Ximage%8!=0) Xdiv8=(Ximage/8)*8+8;
else Xdiv8=Ximage;
if (Yimage%8!=0) Ydiv8=(Yimage/8)*8+8;
else Ydiv8=Yimage;
// The image we encode shall be filled with the last line and the last column
// from the original bitmap, until Ximage and Yimage are divisible by 8
// Load BMP image from disk and complete X
RGB_buffer=(colorRGB *)(malloc(3*Xdiv8*Ydiv8));
if (RGB_buffer==NULL) exitmessage("Not enough memory for the bitmap image.");
if (Ximage%4!=0) nr_fillingbytes=4-(Ximage%4);
else nr_fillingbytes=0;
for (nrline=0;nrline<Yimage;nrline++)
{
fread(RGB_buffer+nrline*Xdiv8,1,Ximage*3,fp_bitmap);
fread(TMPBUF,1,nr_fillingbytes,fp_bitmap);
memcpy(&lastcolor,RGB_buffer+nrline*Xdiv8+Ximage-1,3);
for (column=Ximage;column<Xdiv8;column++)
{memcpy(RGB_buffer+nrline*Xdiv8+column,&lastcolor,3);}
}
Ximage=Xdiv8;
dimline=Ximage*3;tmpline=(colorRGB *)malloc(dimline);
if (tmpline==NULL) exitmessage("Not enough memory.");
//Reorder in memory the inversed bitmap
for (nrline_up=Yimage-1,nrline_dn=0;nrline_up>nrline_dn;nrline_up--,nrline_dn++)
{
memcpy(tmpline,RGB_buffer+nrline_up*Ximage, dimline);
memcpy(RGB_buffer+nrline_up*Ximage,RGB_buffer+nrline_dn*Ximage,dimline);
memcpy(RGB_buffer+nrline_dn*Ximage,tmpline,dimline);
}
// Y completion:
memcpy(tmpline,RGB_buffer+(Yimage-1)*Ximage,dimline);
for (nrline=Yimage;nrline<Ydiv8;nrline++)
{memcpy(RGB_buffer+nrline*Ximage,tmpline,dimline);}
Yimage=Ydiv8;
free(tmpline);fclose(fp_bitmap);
}
void init_all()
{
set_DQTinfo();
set_DHTinfo();
init_Huffman_tables();
set_numbers_category_and_bitcode();
precalculate_YCbCr_tables();
prepare_quant_tables();
}
void main(int argc,char *argv[])
{
char BMP_filename[64];
char JPG_filename[64];
WORD Ximage_original,Yimage_original; //the original image dimensions,
// before we made them divisible by 8
BYTE len_filename;
bitstring fillbits; //filling bitstring for the bit alignment of the EOI marker
if (argc>1) { strcpy(BMP_filename,argv[1]);
if (argc>2) strcpy(JPG_filename,argv[2]);
else { strcpy(JPG_filename,BMP_filename);
len_filename=strlen(BMP_filename);
strcpy(JPG_filename+(len_filename-3),"jpg");
}
}
else exitmessage("Syntax: enc fis.bmp [fis.jpg]");
load_bitmap(BMP_filename, &Ximage_original, &Yimage_original);
fp_jpeg_stream=fopen(JPG_filename,"wb");
init_all();
SOF0info.width=Ximage_original;
SOF0info.height=Yimage_original;
writeword(0xFFD8); //SOI
write_APP0info();
// write_comment("Cris made this JPEG with his own encoder");
write_DQTinfo();
write_SOF0info();
write_DHTinfo();
write_SOSinfo();
bytenew=0;bytepos=7;
main_encoder();
//Do the bit alignment of the EOI marker
if (bytepos>=0) {
fillbits.length=bytepos+1;
fillbits.value=(1<<(bytepos+1))-1;
writebits(fillbits);
}
writeword(0xFFD9); //EOI
free(RGB_buffer); free(category_alloc);free(bitcode_alloc);
fclose(fp_jpeg_stream);
}
/
//END OF SOURCE
/
![《斷舍離》十句感觸[圖]](data:image/gif;base64,R0lGODlhAQABAIAAAP///wAAACwAAAAAAQABAAACAkQBADs=)