ImageMagick提取图像原始数据（ImageData/RawData）

我用的是ImageMagickWand的接口，因为这接口比Core接口更上层，所以官方文档推荐用。

抽取整个图像文件字节数据：

http://www.imagemagick.org/discourse-server/viewtopic.php?f=1&t=20664

抽取图像像素的字节数据：

http://www.imagemagick.org/discourse-server/viewtopic.php?f=6&t=12135

ImageMagick附带的convert工具命令使用：

convert [-option] inputfile outputfile

以下时常用option：

-colorspace

-size

-depth

以下是提取原始数据的命令:

convert -colorspace gray -depth 16 inputfile gray:filename.raw

.raw文件会在convert工具的当前目录下生成,.raw文件就是没有文件头的原始图像像素的字节文件。

以下时Demo:

 // ImageMagick_use_test.cpp : Defines the entry point for the console application.
 //

 #include "stdafx.h"
 #include "wand\MagickWand.h"
 #include "magick\MagickCore.h"
 #include "stdio.h"
 #include "stdlib.h"
 #include "conio.h"
 #include "malloc.h"

 #define OUT

 void ThrowWandException(MagickWand* wand)
 {
     char *description; 

     ExceptionType severity;
     char err_msg[];

     description=MagickGetException(wand,&severity);
     sprintf(err_msg,"%s\nError_Type is %d\n",description,severity);
     //description=(char *) MagickRelinquishMemory(description); 

     printf(err_msg);
 }

 char* __stdcall GetGrayPixelFormat_16bit( const char* fileName, int width, int height, OUT char* pDestImage );

 bool __stdcall GetRGBPixelFormat_16bit( const char* fileName, int width, int height, OUT char* pRed, OUT char* pGreen, OUT char* pBlue);

 int _tmain(int argc, _TCHAR* argv[])
 {

    char *pDestImage = NULL;
    char *pRed =NULL;
    char *pGreen = NULL;
    char *pBlue = NULL;
    //Allocate 1024*5 Buffer in bytes
    pDestImage = (char*)malloc(**);
    pRed = (char*)malloc(**);
    pGreen = (char*)malloc(**);
    pBlue = (char*)malloc(**);

    memset(pDestImage,,**);
    memset(pRed, , **);
    memset(pGreen, , **);
    memset(pBlue, , **);

    pDestImage = GetGrayPixelFormat_16bit( "C:\\Users\\Yajun Dou\\Desktop\\12.jpg", , , pDestImage);

    if(pDestImage == NULL)
    {
        printf("GetGrayPixelFormat_16bit Failed!\n");
    }

    if(GetRGBPixelFormat_16bit("C:\\Users\\Yajun Dou\\Desktop\\12.jpg",,,pRed,pGreen,pBlue)==false)
    {
        printf("GetRGBPixelFormat_16bit Failed!\n");
    }

    free(pDestImage);
    free(pRed);
    free(pGreen);
    free(pBlue);

     return ;
 }

 char* __stdcall GetGrayPixelFormat_16bit( const char* fileName, int width, int height, OUT char* pDestImage )
 {
     MagickBooleanType status;

     MagickWand *magick_wand;

     char* pReturnDestImage = NULL;
     char* pReturnDestImageData = NULL;

     int IMageDepth;

     //Initialize Magick Enviroment

     MagickWandGenesis();
     magick_wand=NewMagickWand();

     //Read image
     status=MagickReadImage(magick_wand,fileName);
     if (status == MagickFalse)
         ThrowWandException(magick_wand);

     //得到图像深度
     IMageDepth = (int)MagickGetImageDepth(magick_wand);

     printf("The Current Image Depth is %d\n",IMageDepth);

     //convert image to grayscale
     status = MagickSetImageColorspace(magick_wand,GRAYColorspace);

     if(status == MagickFalse)
         ThrowWandException(magick_wand);

     status = MagickTransformImageColorspace(magick_wand,GRAYColorspace);

     if(status == MagickFalse)
         ThrowWandException(magick_wand);

     IMageDepth = (int)MagickGetImageDepth(magick_wand);

     printf("The Current Image Depth is %d\n",IMageDepth);

     //得到图像宽度和高度
     int Height;

     Height = (int)MagickGetImageHeight(magick_wand);

     printf("The Current Image Height is %d\n",Height);

     int Width;

     Width = (int)MagickGetImageWidth(magick_wand);

     printf("The Current Image Width is %d\n",Width);

     //得到像素的通道数
     int ImageChannels;
     Image* pImage = NULL;

     pImage = GetImageFromMagickWand(magick_wand);

     if(pImage == NULL)
     {
         return NULL;
     }

     ImageChannels = pImage->channels;

     /*printf("RedChannelDepth is %d\n",MagickGetImageChannelDepth(magick_wand,RedChannel));
     printf("GreenChannelDepth is %d\n",MagickGetImageChannelDepth(magick_wand,GreenChannel));
     printf("BlueChannelDepth is %d\n",MagickGetImageChannelDepth(magick_wand,BlueChannel));
     printf("GrayChannelDepth is %d\n",MagickGetImageChannelDepth(magick_wand,GrayChannel));*/

     if(Width != width || Height != height || IMageDepth !=  || ImageChannels != )
     {

         if(MagickResizeImage(magick_wand,width,height,LanczosFilter,1.0) == MagickFalse)
         {
             ThrowWandException(magick_wand);
         }

         //设置图像深度
         if(MagickSetImageDepth(magick_wand,) == MagickFalse)
         {
             ThrowWandException(magick_wand);
         }
         //设置灰度通道深度
         if(MagickSetImageChannelDepth(magick_wand,GrayChannel,) == MagickFalse)
         {
             ThrowWandException(magick_wand);
         }

     }

     // MagickWriteImages(magick_wand,"C:\\Users\\Yajun Dou\\Desktop\\12_trans1.bmp",MagickFalse);

     IMageDepth = (int)MagickGetImageDepth(magick_wand);

     printf("The Current Image Depth is %d\n",IMageDepth);

     int ImageDataLength;
     int ImageDataSize;
    /* //MagickGetImageBlob函数得到的是整个图像文件的二进制字节流,并非图像数据
     pReturnDestImage = (char*)MagickGetImageBlob(magick_wand,(size_t*)&ImageDataLength);*/
     MagickGetImagePixels(magick_wand,,,width,height,"I",ShortPixel,pDestImage);

     magick_wand=DestroyMagickWand(magick_wand);

     MagickWandTerminus();

     return pDestImage;
 }

 bool __stdcall GetRGBPixelFormat_16bit( const char* fileName, int width, int height, OUT char* pRed, OUT char* pGreen, OUT char* pBlue)
 {
     MagickBooleanType status;

     MagickWand *magick_wand;

     //Initialize Magick Enviroment

     MagickWandGenesis();
     magick_wand=NewMagickWand();

     //Read image
     status=MagickReadImage(magick_wand,fileName);
     if (status == MagickFalse)
     {
         ThrowWandException(magick_wand);
         return false;
     }

     //convert image to RGB three channels
     status = MagickSetImageColorspace(magick_wand,RGBColorspace);

     if(status == MagickFalse)
         ThrowWandException(magick_wand);

     status = MagickTransformImageColorspace(magick_wand,RGBColorspace);

     if(status == MagickFalse)
         ThrowWandException(magick_wand);

     //得到图像深度
     int IMageDepth;

     IMageDepth = (int)MagickGetImageDepth(magick_wand);

     printf("The Current Image Depth is %d\n",IMageDepth);

     //得到图像宽度和高度
     int Height;

     Height = (int)MagickGetImageHeight(magick_wand);

     printf("The Current Image Height is %d\n",Height);

     int Width;

     Width = (int)MagickGetImageWidth(magick_wand);

     printf("The Current Image Width is %d\n",Width);

     //得到像素的通道数
     int ImageChannels;
     Image* pImage = NULL;

     pImage = GetImageFromMagickWand(magick_wand);

     if(pImage == NULL)
     {
         return false;
     }

     ImageChannels = pImage->channels;

     /*printf("RedChannelDepth is %d\n",MagickGetImageChannelDepth(magick_wand,RedChannel));
     printf("GreenChannelDepth is %d\n",MagickGetImageChannelDepth(magick_wand,GreenChannel));
     printf("BlueChannelDepth is %d\n",MagickGetImageChannelDepth(magick_wand,BlueChannel));
     printf("GrayChannelDepth is %d\n",MagickGetImageChannelDepth(magick_wand,GrayChannel));*/

     if(Width != width || Height != height)
     {

         if(MagickResizeImage(magick_wand,width,height,LanczosFilter,1.0) == MagickFalse)
         {
             ThrowWandException(magick_wand);
         }

     }

     // MagickWriteImages(magick_wand,"C:\\Users\\Yajun Dou\\Desktop\\12_trans1.bmp",MagickFalse);

     IMageDepth = (int)MagickGetImageDepth(magick_wand);

     printf("The Current Image Depth is %d\n",IMageDepth);

     int ImageDataLength;
     int ImageDataSize;
     /* //MagickGetImageBlob函数得到的是整个图像文件的二进制字节流,并非图像数据
     pReturnDestImage = (char*)MagickGetImageBlob(magick_wand,(size_t*)&ImageDataLength);*/
     MagickGetImagePixels(magick_wand,,,width,height,"R",ShortPixel,pRed);
     MagickGetImagePixels(magick_wand,,,width,height,"G",ShortPixel,pGreen);
     MagickGetImagePixels(magick_wand,,,width,height,"B",ShortPixel,pBlue);

     magick_wand=DestroyMagickWand(magick_wand);

     MagickWandTerminus();

     return true;

 }

TIPS:MagickWandGenesis()函数是对于整个进程（全局的初始化），一般要在主线程中调用，如果每个函数都调用MagickWandGenesis()，MagickWandTerminus();必然带来巨大性能开销。以上是Demo，所以没管那么多，如果糅合到项目中，必然不能这么写。ImageMagickGetImagePixels,后面的shortpixel是指提取16bit的图像数据，"R" "G"等是指示通道顺序，所以可以"RGB"连接起来写.最后一个参数是输出数据的字节数组。

另外还可以调用MagickExportImagePixels这个接口来得到图像数据。ImageMagickGetImagePixels这个接口貌似是过时的接口，虽然能用。这两个API的参数是一样的。

reference：

http://web.mit.edu/usmanm/MacData/afs/athena/contrib/graphics/share/ImageMagick/www/convert.html