为OpenCV1.0添加cvJpeg2Ipl函数

由于在OpenCV1.0中只提供了从硬盘打开JPEG图像进行解码，有些时候如果JPEG的图像数据是从内存载入的，就无法使用这些曾经很方便高效的接口。为了实现这个目的,我们通过修改OpenCV1.0源码,在其源码包中添加函数,实现把jpeg数据从内存复制到IplImage结构中,这为我们进行相应处理会方便很多,实现过程如下:

修改源码包目录下的otherlibs/highgui目录下的如下源码文件：

1、highgui.h，在其中添加函数的声明：

CVAPI(IplImage*) cvJpeg2Ipl(char *jpegData, int jpegSize);

2、grfmt_jpeg.cpp，在其中添加函数的实现：

1）、添加头文件：

#include "jpeglib.h"

2）、添加源代码：

void mem_init_source(j_decompress_ptr cinfo)

{

//cinfo->src->bytes_in_buffer = g_buf_len;

//cinfo->src->next_input_byte = (unsigned char*)g_buf;

}

boolean mem_fill_input_buffer(j_decompress_ptr cinfo)

{

return true;

}

void mem_skip_input_data(j_decompress_ptr cinfo, long num_bytes)

{

cinfo->src->bytes_in_buffer -= num_bytes;

cinfo->src->next_input_byte += num_bytes;

}

boolean mem_resync_to_restart(j_decompress_ptr cinfo, int desired)

{

return jpeg_resync_to_restart(cinfo, desired);

}

void mem_term_source(j_decompress_ptr cinfo)

{

}

// @jpegData: 内存中的JPEG图像数据流

// @jpegSize：数据流大小

CV_IMPL IplImage*

cvJpeg2Ipl(char *jpegData, int jpegSize)

{

IplImage *_pImg = 0;

jpeg_source_mgr jmgr;

struct jpeg_error_mgr jerr;

struct jpeg_decompress_struct cinfo;

cinfo.err = jpeg_std_error(&jerr);

jpeg_create_decompress(&cinfo);

jmgr.init_source = mem_init_source;

jmgr.fill_input_buffer = mem_fill_input_buffer;

jmgr.skip_input_data = mem_skip_input_data;

jmgr.resync_to_restart = mem_resync_to_restart;

jmgr.term_source = mem_term_source;

jmgr.next_input_byte = (unsigned char*)jpegData;

jmgr.bytes_in_buffer = jpegSize;

cinfo.src = &jmgr;

jpeg_read_header(&cinfo, TRUE);

jpeg_start_decompress(&cinfo);

int nRowSize = cinfo.output_width * cinfo.output_components;

int w =cinfo.output_width;

int h =cinfo.output_height;

char *bmpBuffer=new char[h*w*3];

JSAMPARRAY pBuffer = (*cinfo.mem->alloc_sarray)

((j_common_ptr) &cinfo, 1, nRowSize, 1);

while(cinfo.output_scanline < cinfo.output_height)

{

jpeg_read_scanlines(&cinfo, pBuffer, 1);

int start=nRowSize*(cinfo.output_scanline-1);

for(int i=0;i

{

bmpBuffer[start+i]=pBuffer[0][i];

}

}

jpeg_finish_decompress(&cinfo);

jpeg_destroy_decompress(&cinfo);

_pImg = cvCreateImage(cvSize(w,h),8,3);

for (h=0; h<_pImg->height; h++)

{

for (w=0; w<_pImg->widthStep; w+=3)

{

*(_pImg->imageData+h*_pImg->widthStep+w+0)=*(bmpBuffer+h*_pImg->widthStep+w+2);

*(_pImg->imageData+h*_pImg->widthStep+w+1)=*(bmpBuffer+h*_pImg->widthStep+w+1);

*(_pImg->imageData+h*_pImg->widthStep+w+2)=*(bmpBuffer+h*_pImg->widthStep+w+0);

}

}

delete bmpBuffer;

bmpBuffer=NULL;

return _pImg;

}

修改完成后得新编译安装OpenCV包即可，接下来就可以在程序中包含highgui.h头文件，然后就可以使用cvJpeg2Ipl函数了。