windows7 64位机上，libjpeg-turbo的安装和使用

libjpeg-turbo是对libjpeg的扩展，支持SIMD指令，如X86架构的MMX、SSE、SSE2、3DNOW，ARM架构的NEON，在对jpeg进行编码和解码的过程中能提高速度。

         MMX：多媒体扩展的缩写，第六代CPU芯片重要特点，57条指令。

         SSE2：SIMD流技术扩展2,144个新增指令，被MMX优化过的程序很容易被SSE2进行更深层次的优化。

         NEON：可加速多媒体和信号处理算法，它是ARM系列处理器的128位SIMD架构扩展。

         在速度上，libjpeg-turbo一般是libjpeg的2-4倍。它既能调用libjpegAPI，又可调用TurboJPEG API。可以使用libjpeg-turbo替代libjpeg。

编译libjpeg-turbo：

1、  从https://sourceforge.net/projects/libjpeg-turbo/通过TortoiseSVN下载libjpeg-turbo最新源代码，将其保存到D:\soft\libjpeg-turbo文件夹下；

2、  从http://www.cmake.org/下载最新版的CMake，并安装；

3、  在D:\soft\libjpeg-turbo文件夹下手动创建一个vs2010文件夹；

4、  打开CMake，其中where isthe source code选项，选择D:/soft/libjpeg-turbo/libjpeg-turbo；where to build thebinaries选项，选择D:/soft/libjpeg-turbo/vs2010；

5、  点击Configure，在弹出的对话框中选择VisualStudio 10，其它默认，点击Finish；

6、  如果有红色框显示，继续点击Configure(将CMAKE_INSTALL_PREFIX中的value改为D:\libjpeg-turbo)；

7、  点击Generate，此时会在vs2010文件夹中看到libjpeg-turbo.sln文件；

8、  从https://sourceforge.net/projects/nasm/下载最新版的nasm；

9、  将nasm安装到D:\ProgramFiles\NASM文件夹下，并将其中的nasm.exe和ndisasm.exe两个文件拷贝到C:\ProgramFiles\Microsoft Visual Studio 10.0\VC\bin下(如果是64位，则拷贝到C:\ProgramFiles (x86)\Microsoft Visual Studio 10.0\VC\bin)，将其D:\ProgramFiles\NASM添加到系统环境变量中；

10、             打开libjpeg-turbo.sln，分别在Debug和Release下，选择Solution Explorer里的Solution libjpeg-turbo，点击右键，运行”Rebuild Solution”，然后选中INSTALL, build；

11、             全部完成后会在D:\libjpeg-turbo文件夹下生成bin、doc、lib、include四个文件夹，编译成功(说明：默认的Debgu和Release下生成的所有文件夹都相同，注意区分)；

12、             打开vs2010，新建一个控制台应用程序，为vs2010配置libjpeg-turbo环境：选择View--> Properties Manager-->分别选中Debug和Release上的Microsoft.Cpp.Win32.user，点击右键-->Properties：VC++ Directories，Include Directories：D:\libjpeg-turbo\include；Library Directories：D:\libjpeg-turbo\lib；

13、             选中工程-->Properties-->Configuration Properties-->Linker-->Input-->AdditionalDependencies：Debug和Release，添加相应的.lib库；

14、             将D:\libjpeg-turbo\bin加入到windows系统环境变量Path中，重启。

新建一个控制台工程：

1、将jconfig.h文件拷贝到该工程目录下；

2、stdafx.h:

#pragma once

#include "targetver.h"

#include <stdio.h>

#include "D:/Soft/libjpegturbo/libjpegturbo/jpeglib.h"

#include "stdafx.h"

// TODO: reference any additional headers you need in STDAFX.H
// and not in this file
#ifdef _DEBUG
	#pragma comment(lib, "D:/Soft/libjpegturbo/vs2010/Debug/jpeg-static.lib")
#else
	#pragma comment(lib, "D:/Soft/libjpegturbo/vs2010/Release/jpeg-static.lib")
#endif

#include "stdafx.h"
#include <iostream>

#include <stdio.h>
#include <setjmp.h>
#include <string.h>
#include <stdlib.h>

using namespace std;

int read_JPEG_file(string strImageName)
{
	/* This struct contains the JPEG decompression parameters and pointers to
     * working space (which is allocated as needed by the JPEG library).
     */
	struct jpeg_decompress_struct cinfo;
	/* We use our private extension JPEG error handler.
     * Note that this struct must live as long as the main JPEG parameter
     * struct, to avoid dangling-pointer problems.
     */
	struct jpeg_error_mgr jerr;
	/* More stuff */
	FILE * infile;/* source file */
	JSAMPARRAY buffer;/* Output row buffer */
	int row_stride;/* physical row width in output buffer */

	/* In this example we want to open the input file before doing anything else,
	 * so that the setjmp() error recovery below can assume the file is open.
	 * VERY IMPORTANT: use "b" option to fopen() if you are on a machine that
	 * requires it in order to read binary files.
	 */
	if ((infile = fopen(strImageName.c_str(), "rb")) == NULL) {
		fprintf(stderr, "can‘t open %s\n", strImageName);
		return -1;
	}

	/* Step 1: allocate and initialize JPEG decompression object */
	/* We set up the normal JPEG error routines, then override error_exit. */
	cinfo.err = jpeg_std_error(&jerr);
	/* Establish the setjmp return context for my_error_exit to use. */
	//if (setjmp(jerr.setjmp_buffer)) {
		/* If we get here, the JPEG code has signaled an error.
		 * We need to clean up the JPEG object, close the input file, and return.
		 */
		//jpeg_destroy_decompress(&cinfo);
		//fclose(infile);
		//return -1;
	//}

	/* Now we can initialize the JPEG decompression object. */
	jpeg_create_decompress(&cinfo);

	/* Step 2: specify data source (eg, a file) */
	jpeg_stdio_src(&cinfo, infile);

	/* Step 3: read file parameters with jpeg_read_header() */
	jpeg_read_header(&cinfo, TRUE);
	/* We can ignore the return value from jpeg_read_header since
	 *   (a) suspension is not possible with the stdio data source, and
     *   (b) we passed TRUE to reject a tables-only JPEG file as an error.
     * See libjpeg.txt for more info.
     */
	printf("image_width = %d\n", cinfo.image_width);
	printf("image_height = %d\n", cinfo.image_height);
	printf("num_components = %d\n", cinfo.num_components);

	/* Step 4: set parameters for decompression */
	/* In this example, we don‘t need to change any of the defaults set by
     * jpeg_read_header(), so we do nothing here.
     */
	printf("enter scale M/N:\n");
	//scanf("%d/%d", &cinfo.scale_num, &cinfo.scale_denom);
	cinfo.scale_num = 2;
	cinfo.scale_denom = 4;
	printf("scale to : %d/%d\n", cinfo.scale_num, cinfo.scale_denom);

	/* Step 5: Start decompressor */
	jpeg_start_decompress(&cinfo);
	/* We can ignore the return value since suspension is not possible
     * with the stdio data source.
     */

	//输出的图象的信息
	printf("output_width = %d\n", cinfo.output_width);
	printf("output_height = %d\n", cinfo.output_height);
	printf("output_components = %d\n", cinfo.output_components);

	/* We may need to do some setup of our own at this point before reading
	 * the data.  After jpeg_start_decompress() we have the correct scaled
     * output image dimensions available, as well as the output colormap
     * if we asked for color quantization.
     * In this example, we need to make an output work buffer of the right size.
     */ 
	/* JSAMPLEs per row in output buffer */
	row_stride = cinfo.output_width * cinfo.output_components;
	/* Make a one-row-high sample array that will go away when done with image */
	buffer = (*cinfo.mem->alloc_sarray)((j_common_ptr) &cinfo, JPOOL_IMAGE, row_stride, 1);

	/* Step 6: while (scan lines remain to be read) */
    /*           jpeg_read_scanlines(...); */
	/* Here we use the library‘s state variable cinfo.output_scanline as the
     * loop counter, so that we don‘t have to keep track ourselves.
     */
	while (cinfo.output_scanline < cinfo.output_height) {
    /* jpeg_read_scanlines expects an array of pointers to scanlines.
     * Here the array is only one element long, but you could ask for
     * more than one scanline at a time if that‘s more convenient.
     */
		jpeg_read_scanlines(&cinfo, buffer, 1);
		/* Assume put_scanline_someplace wants a pointer and sample count. */
		//put_scanline_someplace(buffer[0], row_stride);
	}

	/* Step 7: Finish decompression */
	jpeg_finish_decompress(&cinfo);
    /* We can ignore the return value since suspension is not possible
     * with the stdio data source.
     */

	/* Step 8: Release JPEG decompression object */
	/* This is an important step since it will release a good deal of memory. */
	jpeg_destroy_decompress(&cinfo);

	/* After finish_decompress, we can close the input file.
	 * Here we postpone it until after no more JPEG errors are possible,
	 * so as to simplify the setjmp error logic above.  (Actually, I don‘t
	 * think that jpeg_destroy can do an error exit, but why assume anything...)
	 */
	fclose(infile);

    /* At this point you may want to check to see whether any corrupt-data
     * warnings occurred (test whether jerr.pub.num_warnings is nonzero).
     */

	return 0;
}

int write_JPEG_file(string strImageName, int quality)
{
	unsigned char* image_buffer;	/* Points to large array of R,G,B-order data */
	int image_height = 200;	/* Number of rows in image */
	int image_width = 400;	/* Number of columns in image */

	/* This struct contains the JPEG compression parameters and pointers to
     * working space (which is allocated as needed by the JPEG library).
     * It is possible to have several such structures, representing multiple
     * compression/decompression processes, in existence at once.  We refer
     * to any one struct (and its associated working data) as a "JPEG object".
     */
    struct jpeg_compress_struct cinfo;

	/* This struct represents a JPEG error handler.  It is declared separately
     * because applications often want to supply a specialized error handler
     * (see the second half of this file for an example).  But here we just
     * take the easy way out and use the standard error handler, which will
     * print a message on stderr and call exit() if compression fails.
     * Note that this struct must live as long as the main JPEG parameter
     * struct, to avoid dangling-pointer problems.
     */
	struct jpeg_error_mgr jerr;
	/* More stuff */
	FILE * outfile;		/* target file */
	JSAMPROW row_pointer[1];	/* pointer to JSAMPLE row[s] */
	int row_stride;		/* physical row width in image buffer */

	/* Step 1: allocate and initialize JPEG compression object */

    /* We have to set up the error handler first, in case the initialization
     * step fails.  (Unlikely, but it could happen if you are out of memory.)
     * This routine fills in the contents of struct jerr, and returns jerr‘s
     * address which we place into the link field in cinfo.
     */
	cinfo.err = jpeg_std_error(&jerr);
	/* Now we can initialize the JPEG compression object. */
	jpeg_create_compress(&cinfo);

	/* Step 2: specify data destination (eg, a file) */
    /* Note: steps 2 and 3 can be done in either order. */

    /* Here we use the library-supplied code to send compressed data to a
     * stdio stream.  You can also write your own code to do something else.
     * VERY IMPORTANT: use "b" option to fopen() if you are on a machine that
     * requires it in order to write binary files.
     */
	if ((outfile = fopen(strImageName.c_str(), "wb")) == NULL) {
		fprintf(stderr, "can‘t open %s\n", strImageName);
		//exit(1);
		return -1;
	}
	jpeg_stdio_dest(&cinfo, outfile);

	/* Step 3: set parameters for compression */
	/* First we supply a description of the input image.
	 * Four fields of the cinfo struct must be filled in:
	 */
	cinfo.image_width = image_width; 	/* image width and height, in pixels */
	cinfo.image_height = image_height;
	cinfo.input_components = 3;		/* # of color components per pixel */
	cinfo.in_color_space = JCS_RGB; 	/* colorspace of input image */
	/* Now use the library‘s routine to set default compression parameters.
	 * (You must set at least cinfo.in_color_space before calling this,
	 * since the defaults depend on the source color space.)
	 */
	jpeg_set_defaults(&cinfo);
	/* Now you can set any non-default parameters you wish to.
	 * Here we just illustrate the use of quality (quantization table) scaling:
	 */
	jpeg_set_quality(&cinfo, quality, TRUE /* limit to baseline-JPEG values */);

	/* Step 4: Start compressor */
	/* TRUE ensures that we will write a complete interchange-JPEG file.
	 * Pass TRUE unless you are very sure of what you‘re doing.
	 */
	jpeg_start_compress(&cinfo, TRUE);

	/* Step 5: while (scan lines remain to be written) */
	/*           jpeg_write_scanlines(...); */
	/* Here we use the library‘s state variable cinfo.next_scanline as the
	 * loop counter, so that we don‘t have to keep track ourselves.
	 * To keep things simple, we pass one scanline per call; you can pass
	 * more if you wish, though.
	 */
	row_stride = image_width * 3;	/* JSAMPLEs per row in image_buffer */

	image_buffer = new unsigned char[row_stride * cinfo.image_height];
	memset(image_buffer, 0xff, row_stride * cinfo.image_height);
	
	int line = 0;
	//while (cinfo.next_scanline < cinfo.image_height) {
	while (line < cinfo.image_height) {
		/* jpeg_write_scanlines expects an array of pointers to scanlines.
		 * Here the array is only one element long, but you could pass
		 * more than one scanline at a time if that‘s more convenient.
		 */
		//row_pointer[0] = &image_buffer[cinfo.next_scanline * row_stride];
		row_pointer[0] = &image_buffer[line * row_stride];
		jpeg_write_scanlines(&cinfo, row_pointer, 1);

		line ++;
	}

	delete image_buffer;

	/* Step 6: Finish compression */
	jpeg_finish_compress(&cinfo);
	/* After finish_compress, we can close the output file. */
	fclose(outfile);

	/* Step 7: release JPEG compression object */
	/* This is an important step since it will release a good deal of memory. */
	jpeg_destroy_compress(&cinfo);

	return 0;
}

struct Image
{
	int bpp;
	int width;
	int height;
	unsigned char* data;
};

struct jerror_mgr
{
	jpeg_error_mgr base;
	jmp_buf        jmp;
};

METHODDEF(void) jerror_exit(j_common_ptr jinfo)
{
	jerror_mgr* err = (jerror_mgr*)jinfo->err;
	longjmp(err->jmp, 1);
}

METHODDEF(void) joutput_message(j_common_ptr)
{
}

bool Image_LoadJpeg(Image* image, unsigned char* img_data, unsigned int img_size)
{
	jpeg_decompress_struct jinfo;
	jerror_mgr jerr;

	jinfo.err = jpeg_std_error(&jerr.base);
	jerr.base.error_exit = jerror_exit;
	jerr.base.output_message = joutput_message;
	jpeg_create_decompress(&jinfo);

	image->data = NULL;

	if (setjmp(jerr.jmp)) goto bail;

	jpeg_mem_src(&jinfo, img_data, img_size);

	if (jpeg_read_header(&jinfo, TRUE) != JPEG_HEADER_OK) goto bail;

	jinfo.dct_method = JDCT_FLOAT; // change this to JDCT_ISLOW on Android/iOS

	if (!jpeg_start_decompress(&jinfo)) goto bail;

	if (jinfo.num_components != 1 && jinfo.num_components != 3) goto bail;

	image->data = new (std::nothrow) unsigned char [jinfo.output_width * jinfo.output_height * jinfo.output_components];
	if (!image->data) goto bail;

	{
		JSAMPROW ptr = image->data;
		while (jinfo.output_scanline < jinfo.output_height)
		{
			if (jpeg_read_scanlines(&jinfo, &ptr, 1) != 1) goto bail;

			ptr += jinfo.output_width * jinfo.output_components;
		}
	}

	if (!jpeg_finish_decompress(&jinfo)) goto bail;

	image->bpp = jinfo.output_components;
	image->width = jinfo.output_width;
	image->height = jinfo.output_height;

	jpeg_destroy_decompress(&jinfo);

	return true;

bail:
	jpeg_destroy_decompress(&jinfo);
	if (image->data) delete [] image->data;

	return false;
}

struct ImageData {
	unsigned char *pixels;
	long  width;
	long height;
};

int TestImage(string strSrcImageName, string strDstImageName)
{
	//read
	struct jpeg_decompress_struct cinfo_decompress;
	FILE* infile;
	int row_stride;
	struct jpeg_error_mgr jerr;

	if ((infile = fopen(strSrcImageName.c_str(), "rb")) == NULL) {
		fprintf(stderr, "can‘t open %s\n", strSrcImageName);
		return -1;
	}

	cinfo_decompress.err = jpeg_std_error(&jerr);
	jpeg_create_decompress(&cinfo_decompress);
	jpeg_stdio_src(&cinfo_decompress, infile);
	int ret = jpeg_read_header(&cinfo_decompress, TRUE);
	if (ret != JPEG_HEADER_OK) return -1;
	jpeg_start_decompress(&cinfo_decompress);
	row_stride = cinfo_decompress.output_width * cinfo_decompress.output_components;
	int buffer_height = 1;
	JSAMPARRAY buffer = (JSAMPARRAY)malloc(sizeof(JSAMPROW) * buffer_height);
	buffer[0] = (JSAMPROW)malloc(sizeof(JSAMPLE) * row_stride);
	//JSAMPARRAY buffer = (*cinfo_decompress.mem->alloc_sarray)((j_common_ptr)&cinfo_decompress, JPOOL_IMAGE, row_stride, 1);
	ImageData *imageData;
	imageData = new ImageData;
	imageData->width = cinfo_decompress.output_width;
	imageData->height = cinfo_decompress.output_height;

	imageData->pixels = new unsigned char [cinfo_decompress.output_width * cinfo_decompress.output_height * cinfo_decompress.output_components];
	long counter = 0;

	while (cinfo_decompress.output_scanline < cinfo_decompress.output_height) {
		jpeg_read_scanlines(&cinfo_decompress, buffer, 1);
		memcpy(imageData->pixels + counter, buffer[0], row_stride);
		counter += row_stride;
	}

	jpeg_finish_decompress(&cinfo_decompress);
	jpeg_destroy_decompress(&cinfo_decompress);

	fclose(infile);

	//write
	unsigned char* image_buffer;
	int image_height = cinfo_decompress.output_height;
	int image_width = cinfo_decompress.output_width;
	FILE * outfile;
	JSAMPROW row_pointer[1];
	int row_stride_dst;
	struct jpeg_compress_struct cinfo_compress;
	cinfo_compress.err = jpeg_std_error(&jerr);
	jpeg_create_compress(&cinfo_compress);

	if ((outfile = fopen(strDstImageName.c_str(), "wb")) == NULL) {
		fprintf(stderr, "can‘t open %s\n", strDstImageName);
		//exit(1);
		return -1;
	}

	jpeg_stdio_dest(&cinfo_compress, outfile);

	cinfo_compress.image_width = image_width;
	cinfo_compress.image_height = image_height;
	cinfo_compress.input_components = 3;
	cinfo_compress.in_color_space = JCS_YCbCr;

	int quality = 70;
	jpeg_set_defaults(&cinfo_compress);	
	jpeg_set_quality(&cinfo_compress, quality, TRUE);
	jpeg_start_compress(&cinfo_compress, TRUE);

	row_stride_dst = image_width * 3;

	image_buffer = new unsigned char[row_stride_dst * cinfo_compress.image_height];
	memcpy(image_buffer, imageData->pixels, row_stride_dst * cinfo_compress.image_height);

	while (cinfo_compress.next_scanline < cinfo_compress.image_height) {
		row_pointer[0] = &image_buffer[cinfo_compress.next_scanline * row_stride_dst];
		jpeg_write_scanlines(&cinfo_compress, row_pointer, 1);
	}

	jpeg_finish_compress(&cinfo_compress);
	fclose(outfile);
	jpeg_destroy_compress(&cinfo_compress);

	if (imageData) {
		delete imageData;
		imageData = NULL;
	}

	if (image_buffer)
		delete [] image_buffer;
	
	return 0;
}

int main(int argc, char* argv[])
{
	string strImageName = "1.jpg";
	int flag1 = read_JPEG_file(strImageName);
	if (flag1 == 0) cout<<"read ok!"<<endl;
	else cout<<"read error!"<<endl;

	strImageName = "2.bmp";
	int flag2 = write_JPEG_file(strImageName, 80);
	if (flag2 == 0) cout<<"write ok!"<<endl;
	else cout<<"write error!"<<endl;

	string strSrcImageName = "a.jpg";
	string strDstImageName = "b.jpg";
	int flag3 = TestImage(strSrcImageName, strDstImageName);
	if (flag3 == 0) cout<<"test ok!"<<endl;
	else cout<<"test error!"<<endl;

	return 0;
}

参考文献：

1、  http://libjpeg-turbo.virtualgl.org/

2、  http://www.linuxsir.org/bbs/thread374093.html

3、  http://blog.sina.com.cn/s/blog_a5b979d30101af56.html

4、  http://blog.csdn.net/jwzhangjie/article/details/8807409

5、  http://blog.csdn.net/hongwazi_2010/article/details/9153087