|
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[5]; // = "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 struct SOF0infotype {
- 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[64];
- unsigned char QTCbinfo; // = 1 (quantization table for Cb,Cr)
- unsigned char 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
- //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[16]; //at index i = nr of codes with length i
- unsigned char YDC_values[12];
- unsigned char HTYACinfo; // = 0x10
- unsigned char YAC_nrcodes[16];
- unsigned char YAC_values[162]; //we'll use the standard Huffman tables
- unsigned char HTCbDCinfo; // = 1
- unsigned char CbDC_nrcodes[16];
- unsigned char CbDC_values[12];
- unsigned char HTCbACinfo; // = 0x11
- unsigned char CbAC_nrcodes[16];
- unsigned char CbAC_values[162];
- }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[IMAGE_WIDE*IMAGE_HIGH];
- extern unsigned int all_jpeg_data_length;
- unsigned int data2jpg(int image_w,int image_h,unsigned char *ImageData);
复制代码
- //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
- #define Y(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[16]={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[12];
- static bitstring CbDC_HT[12];
- static bitstring YAC_HT[256];
- static bitstring CbAC_HT[256];
- 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[256],YGtab[256],YBtab[256];
- static signed long int CbRtab[256],CbGtab[256],CbBtab[256];
- static signed long int 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
- unsigned short int Ximage,Yimage;// image dimensions divisible by 8
- static signed char YDU[64]; // This is the Data Unit of Y after YCbCr->RGB transformation
- static signed char CbDU[64];
- static signed char CrDU[64];
- static signed short int DU_DCT[64]; // Current DU (after DCT and quantization) which we'll zigzag
- static signed short int DU[64]; //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[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
- };
- //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[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 unsigned char 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) */
- //直流系数的编码(固定值)
- static unsigned char std_dc_luminance_nrcodes[17] = {0, 0, 1, 5, 1, 1, 1, 1, 1, 1, 0, 0, 0, 0, 0, 0, 0};
- static unsigned char std_dc_luminance_values[12] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11};
- static unsigned char std_dc_chrominance_nrcodes[17] = {0,0,3,1,1,1,1,1,1,1,1,1,0,0,0,0,0};
- static unsigned char std_dc_chrominance_values[12] = {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[17] = {0,0,2,1,3,3,2,4,3,5,5,4,4,0,0,1,0x7d};
- static unsigned char 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 unsigned char std_ac_chrominance_nrcodes[17] = {0,0,2,1,2,4,4,3,4,7,5,4,4,0,1,2,0x77};
- static unsigned char 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
- };
- #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[MAIN_BUFFER_LENGTH];
- 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[500*400];
- 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[all_jpeg_data_length] = 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[i]);
- writebyte(DQTinfo.QTCbinfo);
- for (i=0;i<64;i++)
- writebyte(DQTinfo.Cbtable[i]);
- }
- // 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[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]] = (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[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]);
- }
- //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[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];
- }
- //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[i]);
- }
- // 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[posval])
- bytenew|=mask[bytepos];
-
- 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[k]; j++)
- {
- HT[std_table[pos_in_table]].value = codevalue;
- HT[std_table[pos_in_table]].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[nr] = cat;
- bitcode[nr].length = cat;
- bitcode[nr].value = (unsigned short int)nr;
- }
- //Negative numbers
- for (nr=-(nrupper-1); nr<=-nrlower; nr++)
- {
- category[nr] = cat;
- bitcode[nr].length = cat;
- bitcode[nr].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[R]=(signed long int)(65536*0.299+0.5)*R;
- CbRtab[R]=(signed long int)(65536*-0.16874+0.5)*R;
- CrRtab[R]=(signed long int)(32768)*R;
- }
- for (G=0;G<=255;G++)
- {
- YGtab[G]=(signed long int)(65536*0.587+0.5)*G;
- CbGtab[G]=(signed long int)(65536*-0.33126+0.5)*G;
- CrGtab[G]=(signed long int)(65536*-0.41869+0.5)*G;
- }
- for (B=0;B<=255;B++)
- {
- YBtab[B]=(signed long int)(65536*0.114+0.5)*B;
- CbBtab[B]=(signed long int)(32768)*B;
- CrBtab[B]=(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[64] / fdtbl_Cb[64]
- //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[8] =
- {
- 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[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++;
- }
- }
- }
- //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[64];
- float temp;
- signed char ctr;
- unsigned char i;
- for (i=0; i<64; i++)
- datafloat[i] = data[i];
- //DCT转换第一步:按行处理
- 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 */
- }
- //DCT转换第二步:按列处理
- 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 */
- }
- //DCT转换的结果存在datafloat[64]
- //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[i] * fdtbl[i];
- outdata[i] = (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[0x00];
- bitstring M16zeroes=HTAC[0xF0];
- 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[zigzag[i]] = DU_DCT[i];
- Diff = DU[0] - *DC; //这里的*DC不一定是0
- *DC = DU[0]; //因为这里会修改局部参数*DC
- //Encode DC
- if (Diff==0)
- writebits(HTDC[0]); //Diff might be 0
- else
- {
- writebits(HTDC[category[Diff]]);
- writebits(bitcode[Diff]);
- }
- //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[end0pos]==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[i]==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[nrzeroes*16+category[DU[i]]]);
- writebits(bitcode[DU[i]]);
- 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[tmp01*bytes_perline + tmp02 ];
- gp8main_sensor_dest[(tmp01)*perline_dest + tmp02*3 + 0] = gp8main_sensor_source[tmp01*bytes_perline + tmp02 ];
- gp8main_sensor_dest[(tmp01)*perline_dest + tmp02*3 + 1] = gp8main_sensor_source[tmp01*bytes_perline + tmp02 ];
- }
- }
- 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)[location].R;
- G = ((colorRGB *)gp8main_sensor_dest)[location].G;
- B = ((colorRGB *)gp8main_sensor_dest)[location].B;
- YDU[pos]=Y(R,G,B);
- CbDU[pos]=Cb(R,G,B);
- CrDU[pos]=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[64] = "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;
- }
复制代码 |
阿莫论坛20周年了!感谢大家的支持与爱护!!
一只鸟敢站在脆弱的枝条上歇脚,它依仗的不是枝条不会断,而是自己有翅膀,会飞。
|