C API

起因

• 做生物图象处理, 先用python, 速度实在太慢, 用c 选图像库, ImageMagic看上去不错. 可惜, 文档实在太简洁了, 好在open source, 看着源码摸索着走.

开端

• ImageMagic的C API有两种, MagickWand 和 MagickCore , Manual两种API都有一个例子程序. MagickCore是一个低阶的API, 但是更灵活, 将仔细讨论. 读取图像, 计算RGB分量的联合分布R-G , G-B, B-R:

     1 #include <stdio.h>
     2 #include <stdlib.h>
     3 #include <string.h>
     4 #include <time.h>
     5 #include <magick/ImageMagick.h>
     6 
     7 int main(int argc,char **argv)
     8 {
     9   ExceptionInfo
    10     exception;
    11   
    12   Image
    13     *image,
    14     *rgimage,
    15     *gbimage,
    16     *brimage;
    17   
    18   ImageInfo
    19     *image_info;
    20   char
    21     * infilename,
    22     * rgfilename,
    23     * gbfilename,
    24     * brfilename;
    25   PixelPacket * ipix, *rgpix,*gbpix, *brpix;
    26   
    27   unsigned char M[3][256*256];
    28   unsigned char r,g,b;
    29 
    30   infilename = argv[1];
    31   rgfilename = argv[2];
    32   gbfilename = argv[3];
    33   brfilename = argv[4];
    34   
    35   int i,j;
    36   
    37   /*
    38     Initialize the image info structure and read an image.
    39   */
    40   InitializeMagick(*argv);
    41   GetExceptionInfo(&exception);
    42   image_info=CloneImageInfo((ImageInfo *) NULL);
    43   
    44   (void) strcpy(image_info->filename, infilename);
    45   image=ReadImage(image_info,&exception);
    46   if (exception.severity != UndefinedException)
    47     CatchException(&exception);
    48   if (image == (Image *) NULL)
    49     exit(1);
    50   /*
    51     Turn the images into a thumbnail sequence.
    52   */
    53   
    54   fprintf(stderr, "\nImage Info:\n"
    55           "name: %s\n"
    56           "colorspace : %d\n"
    57           "type : %d\n"
    58           "columns: %ld rows : %ld\n"
    59           "depth: %ld colors: %ld\n"
    60           ,
    61           image_info->filename,
    62           image->colorspace, 
    63           GetImageType(image, &exception),
    64           image->columns,
    65           image->rows,
    66           image->depth,
    67           image->colors
    68           );
    69 
    70   ipix = AcquireImagePixels(image, 0, 0,
    71                             image->columns ,image->rows,
    72                             &exception);
    73   fprintf(stderr, "\ncounting ... \n");
    74   memset(M,0,sizeof(M));
    75   for(i=0; i < image->columns*image->rows ; i++)
    76     {
    77       r = ScaleQuantumToChar(ipix[i].red);
    78       g = ScaleQuantumToChar(ipix[i].green);
    79       b = ScaleQuantumToChar(ipix[i].blue);
    80       //if(i%100<10) fprintf(stderr, "(%d,%d,%d)\n", r,g,b);
    81       M[0][r*256 + g] < 255 ? M[0][r*256 + g] += 1:0;
    82       M[1][g*256 + b] < 255 ? M[1][g*256 + b] += 1:0;
    83       M[2][b*256 + r] < 255 ? M[2][b*256 + r] += 1:0;
    84     }
    85   
    86   fprintf(stderr, "Writeing file...\n");
    87   rgimage = ConstituteImage(256,256,"I",CharPixel,M[0],&exception);
    88   gbimage = ConstituteImage(256,256,"I",CharPixel,M[1],&exception);
    89   brimage = ConstituteImage(256,256,"I",CharPixel,M[2],&exception);
    90   
    91   fprintf(stderr, "Writeing file: %s\n", rgfilename);
    92   (void) strcpy(rgimage->filename, rgfilename);
    93   WriteImage(image_info, rgimage);
    94   fprintf(stderr, "Writeing file: %s\n", gbfilename);
    95   (void) strcpy(gbimage->filename, gbfilename);
    96   WriteImage(image_info, gbimage);
    97   fprintf(stderr, "Writeing file: %s\n", brfilename);
    98   (void) strcpy(brimage->filename, brfilename);
    99   WriteImage(image_info, brimage);
   100   
   101   image_info=DestroyImageInfo(image_info);
   102   
   103   DestroyExceptionInfo(&exception);
   104   DestroyMagick();
   105   return(0);
   106 }
  

  CC = gcc
  MFLAGS = `Wand-config --cflags --cppflags`
  MLIBS = `Wand-config --ldflags --libs`
  
  all: wand core
  
  wand: wand.c
          $(CC) $(MFLAGS) wand.c $(MLIBS) -o wand
  core: core.c
          $(CC) $(MFLAGS) wand.c $(MLIBS) -o core
  
  mf: $(CFILE).c
  #       if $CFILE then
          $(CC) $(MFLAGS) $(CFILE).c $(MLIBS) -o $(CFILE)
  rimg: rimg.c
          $(CC) $(MFLAGS) rimg.c $(MLIBS) -o rimg
  
  run-rimg: rimg 
          ./rimg t1.png rg1.png gb1.png br1.png   
          ./rimg t2.png rg2.png gb2.png br2.png
          ./rimg t3.png rg3.png gb3.png br3.png