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 "wandMagickWand.h"
#include "magickMagickCore.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[125];
    
    description=MagickGetException(wand,&severity); 
    sprintf(err_msg,"%s
Error_Type is %d
",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(1920*1200*2);
   pRed = (char*)malloc(1920*1200*2);
   pGreen = (char*)malloc(1920*1200*2);
   pBlue = (char*)malloc(1920*1200*2);
    
   memset(pDestImage,0,1920*1200*2);
   memset(pRed, 0, 1920*1200*2);
   memset(pGreen, 0, 1920*1200*2);
   memset(pBlue, 0, 1920*1200*2);
   
   pDestImage = GetGrayPixelFormat_16bit( "C:\Users\Yajun Dou\Desktop\12.jpg", 1920, 1200, pDestImage);

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

   if(GetRGBPixelFormat_16bit("C:\Users\Yajun Dou\Desktop\12.jpg",1920,1200,pRed,pGreen,pBlue)==false)
   {
       printf("GetRGBPixelFormat_16bit Failed!
");
   }

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

    return 0;
}

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
",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
",IMageDepth);


    //得到图像宽度和高度
    int Height;

    Height = (int)MagickGetImageHeight(magick_wand);

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

    int Width;

    Width = (int)MagickGetImageWidth(magick_wand);

    printf("The Current Image Width is %d
",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
",MagickGetImageChannelDepth(magick_wand,RedChannel));
    printf("GreenChannelDepth is %d
",MagickGetImageChannelDepth(magick_wand,GreenChannel));
    printf("BlueChannelDepth is %d
",MagickGetImageChannelDepth(magick_wand,BlueChannel));
    printf("GrayChannelDepth is %d
",MagickGetImageChannelDepth(magick_wand,GrayChannel));*/



    if(Width != width || Height != height || IMageDepth != 16 || ImageChannels != 3)
    {

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

        //设置图像深度
        if(MagickSetImageDepth(magick_wand,16) == MagickFalse)
        {
            ThrowWandException(magick_wand);
        } 
        //设置灰度通道深度
        if(MagickSetImageChannelDepth(magick_wand,GrayChannel,16) == 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
",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,0,0,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
",IMageDepth);


    //得到图像宽度和高度
    int Height;

    Height = (int)MagickGetImageHeight(magick_wand);

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

    int Width;

    Width = (int)MagickGetImageWidth(magick_wand);

    printf("The Current Image Width is %d
",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
",MagickGetImageChannelDepth(magick_wand,RedChannel));
    printf("GreenChannelDepth is %d
",MagickGetImageChannelDepth(magick_wand,GreenChannel));
    printf("BlueChannelDepth is %d
",MagickGetImageChannelDepth(magick_wand,BlueChannel));
    printf("GrayChannelDepth is %d
",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
",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,0,0,width,height,"R",ShortPixel,pRed);
    MagickGetImagePixels(magick_wand,0,0,width,height,"G",ShortPixel,pGreen);
    MagickGetImagePixels(magick_wand,0,0,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