帮忙看下如何快速实现灰阶图像转Jpg格式。
灰阶图像大小为400*400每个像素点是8bit。
想请教各位：如何将这样的data转换成jpg格式，而且速度要快，我自己做的，大概需要几秒钟才可以转换一幅。
代码如下：
static struct APP0infotype {
unsigned short int marker;// = 0xFFE0
unsigned short int length; // = 16 for usual JPEG, no thumbnail
unsigned char JFIFsignature; // = "JFIF",'\0'
unsigned char versionhi; // 1
unsigned char versionlo; // 1
unsigned char xyunits; // 0 = no units, normal density
unsigned short int xdensity;// 1
unsigned short int ydensity;// 1
unsigned char thumbnwidth; // 0
unsigned char thumbnheight; // 0
}APP0info = {0xFFE0,16,'J','F','I','F',0,1,1,0,1,1,0,0};
static structSOF0infotype {
unsigned short int marker; // = 0xFFC0
unsigned short int length; // = 17 for a truecolor YCbCr JPG
unsigned char precision ;// Should be 8: 8 bits/sample
unsigned short int height ;
unsigned short int width;
unsigned char nrofcomponents;//Should be 3: We encode a truecolor JPG
unsigned char IdY;// = 1
unsigned char HVY; // sampling factors for Y (bit 0-3 vert., 4-7 hor.)
unsigned char QTY;// Quantization Table number for Y = 0
unsigned char IdCb; // = 2
unsigned char HVCb;
unsigned char QTCb; // 1
unsigned char IdCr; // = 3
unsigned char HVCr;
unsigned char 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
//DQT说明：Define Quantization Table
static struct DQTinfotype
{
unsigned short int marker;// = 0xFFDB
unsigned short int length;// = 132
unsigned char QTYinfo;// = 0:bit 0..3: number of QT = 0 (table for Y)
// bit 4..7: precision of QT, 0 = 8 bit
unsigned char Ytable;
unsigned char QTCbinfo; // = 1 (quantization table for Cb,Cr)
unsigned char Cbtable;
}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
//说明DHT：Define Huffman Table
/*
哈夫曼编码表说明(是 "熵编码" 的一种形式)
哈夫曼(Huffman)编码是一种常用的压缩编码方法，是Huffman于1952年为压缩文本文件建立的。它的基本原理是频繁使用的数据用较短的代码
代替，较少使用的数据用较长的代码代替，每个数据的代码各不相同。这些代码都是二进制码，且码的长度是可变的。举个例子：假设一个文件中
出现了8种符号S0,S1,S2,S3,S4,S5,S6,S7，那么每种符号要编码，至少需要3比特。假设编码成000,001,010,011,100,101,110,111(称做码字)。
那么符号序列S0S1S7S0S1S6S2S2S3S4S5S0S0S1编码后变成000001111000001110010010011100101000000001，共用了42比特。我们发现S0，S1，S2
这三个符号出现的频率比较大，其它符号出现的频率比较小，如果我们采用一种编码方案使得S0，S1，S2的码字短，其它符号的码字长，这样就
能够减少占用的比特数。例如，我们采用这样的编码方案：S0到S7的码字分别01,11,101,0000,0001,0010,0011,100，那么上述符号序列变成
011110001110011101101000000010010010111，共用了39比特，尽管有些码字如S3，S4，S5，S6变长了(由3位变成4位)，但使用频繁的几个码字
如S0，S1变短了，所以实现了压缩。
上述的编码是如何得到的呢？随意乱写是不行的。编码必须保证不能出现一个码字和另一个的前几位相同的情况，比如说，如果S0的码字为01，
S2的码字为011，那么当序列中出现011时，你不知道是S0的码字后面跟了个1，还是完整的一个S2的码字。我们给出的编码能够保证这一点。
下面给出具体的Huffman编码算法
(1)首先统计出每个符号出现的频率，上例S0到S7的出现频率分别为4/14，3/14，2/14，1/14，1/14，1/14，1/14，1/14
(2)从左到右把上述频率按从小到大的顺序排列
(3)每一次选出最小的两个值，作为二叉树的两个叶子节点，将和作为它们的根节点，这两个叶子节点不再参与比较，新的根节点参与比较
(4)重复(3)，直到最后得到和为1的根节点
(5)将形成的二叉树的左节点标0，右节点标1。把从最上面的根节点到最下面的叶子节点途中遇到的0,1序列串起来，就得到了各个符号的编码
产生Huffman编码需要对原始数据扫描两遍。第一遍扫描要精确地统计出原始数据中，每个值出现的频率，第二遍是建立Huffman树并进行编码。
由于需要建立二叉树并遍历二叉树生成编码，因此数据压缩和还原速度都较慢，但简单有效，因而得到广泛的应用
*/
static struct DHTinfotype
{
unsigned short int marker; // = 0xFFC4
unsigned short int length; //0x01A2
unsigned char 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
unsigned char YDC_nrcodes; //at index i = nr of codes with length i
unsigned char YDC_values;
unsigned char HTYACinfo; // = 0x10
unsigned char YAC_nrcodes;
unsigned char YAC_values; //we'll use the standard Huffman tables
unsigned char HTCbDCinfo; // = 1
unsigned char CbDC_nrcodes;
unsigned char CbDC_values;
unsigned char HTCbACinfo; // = 0x11
unsigned char CbAC_nrcodes;
unsigned char CbAC_values;
}DHTinfo;
static struct SOSinfotype {
unsigned short int marker;// = 0xFFDA
unsigned short int length; // = 12
unsigned char nrofcomponents; // Should be 3: truecolor JPG
unsigned char IdY; //1
unsigned char HTY; //0 // bits 0..3: AC table (0..3)
// bits 4..7: DC table (0..3)
unsigned char IdCb; //2
unsigned char HTCb; //0x11
unsigned char IdCr; //3
unsigned char HTCr; //0x11
unsigned char 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
{
unsigned char B,G,R;
}colorRGB;
typedef struct
{
unsigned char length;
unsigned short int value;
}bitstring;
//extern unsigned char all_jpeg_data;
extern unsigned int all_jpeg_data_length;
unsigned int data2jpg(int image_w,int image_h,unsigned char *ImageData);
//通过查表，将RGB变成YCrBr
//因为进行DCT变换的数据必须在-128 -- 127之间，所以要减掉128；但从公式可见，只有R不是范围内，所以只有R减128
#defineY(R,G,B) ((unsigned char)( (YRtab[(R)]+YGtab[(G)]+YBtab[(B)])>>16 ) - 128)
#define Cb(R,G,B) ((unsigned char)( (CbRtab[(R)]+CbGtab[(G)]+CbBtab[(B)])>>16 ))
#define Cr(R,G,B) ((unsigned char)( (CrRtab[(R)]+CrGtab[(G)]+CrBtab[(B)])>>16 ))
#define writeword(w) writebyte((w)/256);writebyte((w)%256);
static unsigned char bytenew=0; // The byte that will be written in the JPG file
static signed char bytepos=7; //bit position in the byte we write (bytenew)
static unsigned short int mask={1,2,4,8,16,32,64,128,256,512,1024,2048,4096,8192,16384,32768};
//下面是我们要用到的哈夫曼表数据(两个直流分量，两个交流分量)
static bitstring YDC_HT;
static bitstring CbDC_HT;
static bitstring YAC_HT;
static bitstring CbAC_HT;
static unsigned char *category_alloc;
static unsigned char *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 signed long int table because we'll scale values by 2^16 and work with integers
static signed long int YRtab,YGtab,YBtab;
static signed long int CbRtab,CbGtab,CbBtab;
static signed long int CrRtab,CrGtab,CrBtab;
static float fdtbl_Y;
static float fdtbl_Cb; //the same with the fdtbl_Cr
colorRGB *RGB_buffer; //image to be encoded
unsigned short int Ximage,Yimage;// image dimensions divisible by 8
static signed char YDU; // This is the Data Unit of Y after YCbCr->RGB transformation
static signed char CbDU;
static signed char CrDU;
static signed short int DU_DCT; // Current DU (after DCT and quantization) which we'll zigzag
static signed short int DU; //zigzag reordered DU which will be Huffman coded
//说明：按'之'字形量化DCT系数的序号，可以增加连续的0系数的个数
static unsigned char zigzag =
{
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
};
//说明：下面是亮度与色度的量化表，本量化表经测试在电视图像是最佳的(除二后也可得到不错的效果)
//luminance：亮度 chrominance：色度
static unsigned char std_luminance_qt =
{
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 unsigned char std_chrominance_qt =
{
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) */
//直流系数的编码(固定值)
static unsigned char std_dc_luminance_nrcodes = {0, 0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0};
static unsigned char std_dc_luminance_values= {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
static unsigned char std_dc_chrominance_nrcodes = {0,0,3,1,1,1,1,1,1,1,1,1,0,0,0,0,0};
static unsigned char std_dc_chrominance_values= {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
//交流系数的编码(固定值)
static unsigned char std_ac_luminance_nrcodes = {0,0,2,1,3,3,2,4,3,5,5,4,4,0,0,1,0x7d};
static unsigned char std_ac_luminance_values =
{
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 unsigned char std_ac_chrominance_nrcodes = {0,0,2,1,2,4,4,3,4,7,5,4,4,0,1,2,0x77};
static unsigned char std_ac_chrominance_values =
{
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
};
#define QUA 50
#define MAIN_BUFFER_LENGTH 358752
#define CATEGORY_ALLOC 40000
#define BITCODE_ALLOC (40000*1) //长为65535*3
#define SENDOR_SOURCE (1280 * 1 * 8) //sensor每次取8行数据，表示最多支持每行1280点，每点最多三字节
#define SENDOR_DEST (1280 * 1 * 8) //sensor采样转后后数据，必须是24位的
unsigned char g8main_bigbuffer;
unsigned char *gp8main_category = g8main_bigbuffer;
bitstring *gp8main_bitcode= (bitstring *)(g8main_bigbuffer + CATEGORY_ALLOC);
unsigned char *gp8main_sensor_source = g8main_bigbuffer + CATEGORY_ALLOC + BITCODE_ALLOC;
unsigned char *gp8main_sensor_dest = g8main_bigbuffer + CATEGORY_ALLOC + BITCODE_ALLOC + SENDOR_SOURCE;
unsigned char all_jpeg_data;
unsigned int all_jpeg_data_length=0;
unsigned int ImageWdith=0;
unsigned int ImageHeight=0;
unsigned long int bytes_perline;
void writebyte(unsigned long int data)
{
all_jpeg_data = data;
all_jpeg_data_length++;
}
//Nothing to overwrite for APP0info
void write_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);
}
// We should overwrite width and height
void write_SOF0info()
{
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()
{
unsigned char i;
writeword(DQTinfo.marker);
writeword(DQTinfo.length);
writebyte(DQTinfo.QTYinfo);
for (i=0;i<64;i++)
writebyte(DQTinfo.Ytable);
writebyte(DQTinfo.QTCbinfo);
for (i=0;i<64;i++)
writebyte(DQTinfo.Cbtable);
}
// Set quantization table and zigzag reorder it
void set_quant_table(unsigned char *basic_table,unsigned char scale_factor,unsigned char *newtable)
{
unsigned char i;
long temp;
for (i = 0; i < 64; i++)
{
temp = ((long) basic_table * 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] = (unsigned char) temp;
}
}
//DQT说明：Define Quantization Table
//功能：初始化量化表
void set_DQTinfo()
{
unsigned char scalefactor = QUA;
DQTinfo.marker=0xFFDB;
DQTinfo.length=132;
DQTinfo.QTYinfo=0;
DQTinfo.QTCbinfo=1;
set_quant_table(std_luminance_qt,scalefactor,DQTinfo.Ytable); //将亮度表写入Y表
set_quant_table(std_chrominance_qt,scalefactor,DQTinfo.Cbtable); //将色度表写入C表
}
//DHT说明：Define Huffman Table
//功能：初始化哈夫曼表
void write_DHTinfo()
{
unsigned char i;
writeword(DHTinfo.marker);
writeword(DHTinfo.length);
writebyte(DHTinfo.HTYDCinfo);
for (i=0;i<16;i++)
writebyte(DHTinfo.YDC_nrcodes);
for (i=0;i<=11;i++)
writebyte(DHTinfo.YDC_values);
writebyte(DHTinfo.HTYACinfo);
for (i=0;i<16;i++)
writebyte(DHTinfo.YAC_nrcodes);
for (i=0;i<=161;i++)
writebyte(DHTinfo.YAC_values);
writebyte(DHTinfo.HTCbDCinfo);
for (i=0;i<16;i++)
writebyte(DHTinfo.CbDC_nrcodes);
for (i=0;i<=11;i++)
writebyte(DHTinfo.CbDC_values);
writebyte(DHTinfo.HTCbACinfo);
for (i=0;i<16;i++)
writebyte(DHTinfo.CbAC_nrcodes);
for (i=0;i<=161;i++)
writebyte(DHTinfo.CbAC_values);
}
//DHT：Define Huffman Table
//说明：将表数据填入DHT数据结构
void set_DHTinfo()
{
unsigned char i;
DHTinfo.marker=0xFFC4;
DHTinfo.length=0x01A2;
DHTinfo.HTYDCinfo=0;
for (i=0; i<16; i++)
DHTinfo.YDC_nrcodes = std_dc_luminance_nrcodes;
for (i=0; i<=11; i++)
DHTinfo.YDC_values = std_dc_luminance_values;
DHTinfo.HTYACinfo = 0x10;
for (i=0; i<16; i++)
DHTinfo.YAC_nrcodes = std_ac_luminance_nrcodes;
for (i=0;i<=161;i++)
DHTinfo.YAC_values = std_ac_luminance_values;
DHTinfo.HTCbDCinfo = 1;
for (i=0;i<16;i++)
DHTinfo.CbDC_nrcodes = std_dc_chrominance_nrcodes;
for (i=0;i<=11;i++)
DHTinfo.CbDC_values = std_dc_chrominance_values;
DHTinfo.HTCbACinfo = 0x11;
for (i=0;i<16;i++)
DHTinfo.CbAC_nrcodes = std_ac_chrominance_nrcodes;
for (i=0; i<=161; i++)
DHTinfo.CbAC_values = std_ac_chrominance_values;
}
//Nothing to overwrite for SOSinfo
//说明SOS：Start of Scan
void write_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);
}
//在文件数据内加入注释的，可以不用
void write_comment(char *comment)
{
unsigned short int i,length;
writeword(0xFFFE); //The COM marker
length = strlen((const char *)comment);
writeword(length+2);
for (i=0; i<length; i++)
writebyte(comment);
}
// A portable version; it should be done in assembler
void writebits(bitstring bs)
{
unsigned short int value;
signed char 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)
bytenew|=mask;
posval--;
bytepos--;
if (bytepos<0)
{
if (bytenew==0xFF)
{
writebyte(0xFF);
writebyte(0);
}
else
{
writebyte(bytenew);
}
bytepos=7;
bytenew=0;
}
}
}
//哈夫曼表的生成原理分析
//用常量表就可以生成哈夫曼表(两个常量表生成一个哈夫曼表)
void compute_Huffman_table(unsigned char *nrcodes,unsigned char *std_table,bitstring *HT)
{
unsigned char k,j;
unsigned char pos_in_table;
unsigned short int codevalue;
codevalue = 0;
pos_in_table = 0;
for (k=1; k<=16; k++)
{
for (j=1; j<=nrcodes; j++)
{
HT].value = codevalue;
HT].length= k;
pos_in_table ++;
codevalue ++;
}
codevalue *= 2;
}
}
//初始化哈夫曼表：只有四个表YDC，YAC，CbDC，CbAC(Cr的与Cb的相同)
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);
}
//category：种类
//功能：生成category / bitcode两个数组，供压缩时使用
void set_numbers_category_and_bitcode()
{
signed long int nr;
signed long int nrlower,nrupper;
unsigned char cat;
category_alloc = gp8main_category;
category = category_alloc+32767;
bitcode_alloc = gp8main_bitcode;
bitcode = bitcode_alloc+32767;
nrlower = 1;
nrupper = 2;
//从数组的中间向两头写数据
for (cat=1; cat<=15; cat++)
{
//Positive numbers
for (nr=nrlower; nr<nrupper; nr++)
{
category = cat;
bitcode.length = cat;
bitcode.value = (unsigned short int)nr;
}
//Negative numbers
for (nr=-(nrupper-1); nr<=-nrlower; nr++)
{
category = cat;
bitcode.length = cat;
bitcode.value = (unsigned short int)(nrupper-1+nr);
}
nrlower <<= 1;
nrupper <<= 1;
}
}
//说明：生成YCbCr表，供RGB转化时的查表
//Y(n)=0.114B(n)+0.587G(n)+0.299R(n)
//Cb(n)=0.5B(n)-0.3313G(n)-0.1687R(n)
//Cr(n)=0.0813B(n)-0.14187G(n)+0.5R(n)
void precalculate_YCbCr_tables()
{
unsigned short int R,G,B;
for (R=0;R<=255;R++)
{
YRtab=(signed long int)(65536*0.299+0.5)*R;
CbRtab=(signed long int)(65536*-0.16874+0.5)*R;
CrRtab=(signed long int)(32768)*R;
}
for (G=0;G<=255;G++)
{
YGtab=(signed long int)(65536*0.587+0.5)*G;
CbGtab=(signed long int)(65536*-0.33126+0.5)*G;
CrGtab=(signed long int)(65536*-0.41869+0.5)*G;
}
for (B=0;B<=255;B++)
{
YBtab=(signed long int)(65536*0.114+0.5)*B;
CbBtab=(signed long int)(32768)*B;
CrBtab=(signed long int)(65536*-0.08131+0.5)*B;
}
}
//说明：8X8的区域进行DCT变换表的准备,即量化表fdtbl_Y / fdtbl_Cb
//生成本量化表时，只用生成一次，注重与ARM环境的差别
void prepare_quant_tables()
{
double aanscalefactor =
{
1.0,
1.387039845,
1.306562965,
1.175875602,
1.0,
0.785694958,
0.541196100,
0.275899379
};
unsigned char row, col;
unsigned char i = 0;
for (row = 0; row < 8; row++)
{
for (col = 0; col < 8; col++)
{
fdtbl_Y = (float) (1.0 / ((double) DQTinfo.Ytable] *
aanscalefactor * aanscalefactor * 8.0));
fdtbl_Cb = (float) (1.0 / ((double) DQTinfo.Cbtable] *
aanscalefactor * aanscalefactor * 8.0));
i++;
}
}
}
//说明：前向DCT转换，并且进行量化
void fdct_and_quantization(signed char *data,float *fdtbl,signed short int *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;
float temp;
signed char ctr;
unsigned char i;
for (i=0; i<64; i++)
datafloat = data;
//DCT转换第一步：按行处理
dataptr=datafloat;
for (ctr = 7; ctr >= 0; ctr--)
{
tmp0 = dataptr + dataptr;
tmp7 = dataptr - dataptr;
tmp1 = dataptr + dataptr;
tmp6 = dataptr - dataptr;
tmp2 = dataptr + dataptr;
tmp5 = dataptr - dataptr;
tmp3 = dataptr + dataptr;
tmp4 = dataptr - dataptr;
/* Even part */
tmp10 = tmp0 + tmp3; /* phase 2 */
tmp13 = tmp0 - tmp3;
tmp11 = tmp1 + tmp2;
tmp12 = tmp1 - tmp2;
dataptr = tmp10 + tmp11; /* phase 3 */
dataptr = tmp10 - tmp11;
z1 = (tmp12 + tmp13) * ((float) 0.707106781); /* c4 */
dataptr = tmp13 + z1; /* phase 5 */
dataptr = 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 = z13 + z2; /* phase 6 */
dataptr = z13 - z2;
dataptr = z11 + z4;
dataptr = z11 - z4;
dataptr += 8; /* advance pointer to next row */
}
//DCT转换第二步：按列处理
dataptr = datafloat;
for (ctr = 7; ctr >= 0; ctr--)
{
tmp0 = dataptr + dataptr;
tmp7 = dataptr - dataptr;
tmp1 = dataptr + dataptr;
tmp6 = dataptr - dataptr;
tmp2 = dataptr + dataptr;
tmp5 = dataptr - dataptr;
tmp3 = dataptr + dataptr;
tmp4 = dataptr - dataptr;
/* Even part */
tmp10 = tmp0 + tmp3; /* phase 2 */
tmp13 = tmp0 - tmp3;
tmp11 = tmp1 + tmp2;
tmp12 = tmp1 - tmp2;
dataptr = tmp10 + tmp11; /* phase 3 */
dataptr = tmp10 - tmp11;
z1 = (tmp12 + tmp13) * ((float) 0.707106781); /* c4 */
dataptr = tmp13 + z1; /* phase 5 */
dataptr = 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 = z13 + z2; /* phase 6 */
dataptr = z13 - z2;
dataptr = z11 + z4;
dataptr = z11 - z4;
dataptr++; /* advance pointer to next column */
}
//DCT转换的结果存在datafloat
//对DCT转换的结果进行量化处理，结果存在outdata[]内
for (i = 0; i < 64; i++)
{
/* Apply the quantization and scaling factor */
temp = datafloat * fdtbl;
outdata = (signed short int) ((signed short int)(temp + 16384.5) - 16384);
}
}
void process_DU(signed char *ComponentDU, float *fdtbl,signed short int *DC, bitstring *HTDC, bitstring *HTAC)
{
bitstring EOB=HTAC;
bitstring M16zeroes=HTAC;
unsigned char i;
unsigned char startpos;
unsigned char end0pos;
unsigned char nrzeroes;
unsigned char nrmarker;
signed short int Diff;
//要函数进行DCT变换处理，并且进行量化，量化的结果存在DU_DCT内
fdct_and_quantization(ComponentDU,fdtbl,DU_DCT);
//==============================以下对量化的结果进行压缩==============================
//对DU_DCT[]按 '之' 字重新排列，存在DU[]内
for (i=0; i<=63; i++)
DU] = DU_DCT;
Diff = DU - *DC; //这里的*DC不一定是0
*DC = DU; //因为这里会修改局部参数*DC
//Encode DC
if (Diff==0)
writebits(HTDC); //Diff might be 0
else
{
writebits(HTDC]);
writebits(bitcode);
}
//Encode ACs
//先将后面的0全找出来，真正要处理的是头部的非零部分
for (end0pos=63; (end0pos>0)&&(DU==0); end0pos--);
//end0pos = first element in reverse order !=0
if (end0pos==0)
{
writebits(EOB);
return;
}
//非零部分的处理方法
//但是非零部分的内部，可能还有单个或连续的零，也要过滤掉，不处理
//所以真正处理的，只有非零部分内的非零的数据
i=1;
while (i <= end0pos)
{
startpos=i;
//过滤掉里面的0
for (; (DU==0)&&(i<=end0pos);i++) ;
nrzeroes = i-startpos;
//如果内部连续0个数超过16个要做以下处理
if (nrzeroes>=16)
{
for (nrmarker=1; nrmarker<=nrzeroes/16; nrmarker++)
writebits(M16zeroes);
nrzeroes = nrzeroes%16;
}
writebits(HTAC]]);
writebits(bitcode]);
i++;
}
//EOB是每帧数据(8*8)的结束村记
if (end0pos!=63)
writebits(EOB);
}
/*=============================================================================
功能说明：
将8行的sensor数据加载到gp8main_sensor_source，并且变成24bit数据后放到
gp8main_sensor_dest
返回：
NULL
备注：
本函数是摸拟ARM来做，因为真正的数据来自于sensor
//===========================================================================*/
void main_load8line_form_sensor(unsigned short int linenum,unsigned char *data)
{
unsigned long int tmp01,tmp02;
unsigned long int perline_dest = bytes_perline * 3 ;
gp8main_sensor_source = (unsigned char*)data+(linenum*bytes_perline);
//16bit的数据转成24bit
for(tmp01 = 0; tmp01 < 8; tmp01 ++)
{
for(tmp02 = 0; tmp02 < ImageWdith; tmp02 ++)
{
gp8main_sensor_dest[(tmp01)*perline_dest + tmp02*3 + 2] = gp8main_sensor_source;
gp8main_sensor_dest[(tmp01)*perline_dest + tmp02*3 + 0] = gp8main_sensor_source;
gp8main_sensor_dest[(tmp01)*perline_dest + tmp02*3 + 1] = gp8main_sensor_source;
}
}
tmp01 = 0;
}
//将8X8单元RGB数据从RGB_buffer[]内取出，转成YCbCr，同时存储到YDU[]/CbDU[]/CrDU[]内去
void load_data_units_from_RGB_buffer(unsigned short int xpos,unsigned short int ypos)
{
unsigned char x,y;
unsigned char pos=0;
unsigned long int location;
unsigned char R,G,B;
location = xpos;
for (y=0; y<8; y++)
{
for (x=0; x<8; x++)
{
R = ((colorRGB *)gp8main_sensor_dest).R;
G = ((colorRGB *)gp8main_sensor_dest).G;
B = ((colorRGB *)gp8main_sensor_dest).B;
YDU=Y(R,G,B);
CbDU=Cb(R,G,B);
CrDU=Cr(R,G,B);
location++;
pos++;
}
location += ImageWdith-8; //换行
}
}
void main_encoder(unsigned char *image)
{
signed short int DCY=0,DCCb=0,DCCr=0; //DC coefficients used for differential encoding
unsigned short int xpos,ypos;
for(ypos=0;ypos<ImageHeight;ypos += 8)
{
main_load8line_form_sensor(ypos,image);
for(xpos=0;xpos<ImageWdith;xpos += 8)
{
load_data_units_from_RGB_buffer(xpos,ypos);
//对Y，Cb，Cr各自进行量化(Y量化表，Cb与Cr表相同)
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 init_all()
{
set_DQTinfo();
set_DHTinfo();
init_Huffman_tables();
set_numbers_category_and_bitcode();
precalculate_YCbCr_tables();
prepare_quant_tables();
}
// 入口函数
// image_w 和image_h为图像的宽和高，一定要为8的倍数
//ImageData 为原始图像数据
// 图像输出地址在JPG_filename中
unsigned int data2jpg(int image_w,int image_h,unsigned char *ImageData)
{
// unsigned int i;
// char JPG_filename = "c:/test.jpg";
bitstring fillbits; //filling bitstring for the bit alignment of the EOI marker
all_jpeg_data_length=0;
ImageWdith = image_w;
ImageHeight = image_h;
bytes_perline = ((ImageWdith * 1 + 3) / 4) * 4;
init_all();
SOF0info.width = (unsigned short int)ImageWdith; //Ximage_original;
SOF0info.height = (unsigned short int)ImageHeight; //Yimage_original;
writeword(0xFFD8); //SOI
write_APP0info();
write_DQTinfo();
write_SOF0info();
write_DHTinfo();
write_SOSinfo();
bytenew = 0;
bytepos = 7;
main_encoder(ImageData);
//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
return all_jpeg_data_length;
} 运行平台呢？打算跑 FPGA 么？这个代码看不出 HDL 的影子啊。
Windows 下倒是可以用 Gdiplus 做，系统标准的图像库，可以创建/保存 BMP/JPG/PNG/GIF/TIFF 格式图片。
流程大致是：创建 Gdiplus::Bitmap 实例 -> 获取图像数据区指针并访问（写入你的图像） -> Gdiplus::Bitmap::Save 指定使用 JPG 编码器。
当然 JPG 编出来是有损的，推荐使用 PNG。 1：如果是灰度图的话，只用处理Y分量
2：代码里面大量的浮点运算，而且有一次RGB到YUV的转换。看看输入能不能改为YUV的数据；
3：为什么不直接使用libjpeg等开源库
4：代码要是在ARM上运行，建议使用NEON进行优化
5：各个模块做成异步的，例如，RGB2YUV和DCT变换可以做成流水线的
另外代码可能有问题，没有跑通，例如：“//16bit的数据转成24bit”的部分； t3486784401 发表于 2018-11-14 19:54
运行平台呢？打算跑 FPGA 么？这个代码看不出 HDL 的影子啊。
Windows 下倒是可以用 Gdiplus 做，系统标准 ...
fpga内核搞，相当于纯C语言做jpg jm2011 发表于 2018-11-15 14:39
1：如果是灰度图的话，只用处理Y分量
2：代码里面大量的浮点运算，而且有一次RGB到YUV的转换。看看输入能不 ...
是啊 ，标准的库中，大量的float运算，各种嵌套循环，100M的内核跑起来生不如死。 另外 这个问题已经解决了，用的是自己写的行程编码方式。
页:
[1]