1. C API

1.1. 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.

1.2. 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 
     2 
     3 #include <stdio.h>
     4 #include <stdlib.h>
     5 #include <string.h>
     6 #include <time.h>
     7 #include <magick/ImageMagick.h>
     8 
     9 int main(int argc,char **argv)
    10 {
    11   ExceptionInfo
    12     exception;
    13   
    14   Image
    15     *image,
    16     *rgimage,
    17     *gbimage,
    18     *brimage;
    19   
    20   ImageInfo
    21     *image_info;
    22   char
    23     * infilename,
    24     * rgfilename,
    25     * gbfilename,
    26     * brfilename;
    27   PixelPacket * ipix, *rgpix,*gbpix, *brpix;
    28   
    29   unsigned char M[3][256*256];
    30   unsigned char r,g,b;
    31 
    32   infilename = argv[1];
    33   rgfilename = argv[2];
    34   gbfilename = argv[3];
    35   brfilename = argv[4];
    36   
    37   int i,j;
    38   
    39   /*
    40     Initialize the image info structure and read an image.
    41   */
    42   InitializeMagick(*argv);
    43   GetExceptionInfo(&exception);
    44   image_info=CloneImageInfo((ImageInfo *) NULL);
    45   
    46   (void) strcpy(image_info->filename, infilename);
    47   image=ReadImage(image_info,&exception);
    48   if (exception.severity != UndefinedException)
    49     CatchException(&exception);
    50   if (image == (Image *) NULL)
    51     exit(1);
    52   /*
    53     Turn the images into a thumbnail sequence.
    54   */
    55   
    56   fprintf(stderr, "\nImage Info:\n"
    57           "name: %s\n"
    58           "colorspace : %d\n"
    59           "type : %d\n"
    60           "columns: %ld rows : %ld\n"
    61           "depth: %ld colors: %ld\n"
    62           ,
    63           image_info->filename,
    64           image->colorspace, 
    65           GetImageType(image, &exception),
    66           image->columns,
    67           image->rows,
    68           image->depth,
    69           image->colors
    70           );
    71 
    72   ipix = AcquireImagePixels(image, 0, 0,
    73                             image->columns ,image->rows,
    74                             &exception);
    75   fprintf(stderr, "\ncounting ... \n");
    76   memset(M,0,sizeof(M));
    77   for(i=0; i < image->columns*image->rows ; i++)
    78     {
    79       r = ScaleQuantumToChar(ipix[i].red);
    80       g = ScaleQuantumToChar(ipix[i].green);
    81       b = ScaleQuantumToChar(ipix[i].blue);
    82       //if(i%100<10) fprintf(stderr, "(%d,%d,%d)\n", r,g,b);
    83       M[0][r*256 + g] < 255 ? M[0][r*256 + g] += 1:0;
    84       M[1][g*256 + b] < 255 ? M[1][g*256 + b] += 1:0;
    85       M[2][b*256 + r] < 255 ? M[2][b*256 + r] += 1:0;
    86     }
    87   
    88   fprintf(stderr, "Writeing file...\n");
    89   rgimage = ConstituteImage(256,256,"I",CharPixel,M[0],&exception);
    90   gbimage = ConstituteImage(256,256,"I",CharPixel,M[1],&exception);
    91   brimage = ConstituteImage(256,256,"I",CharPixel,M[2],&exception);
    92   
    93   fprintf(stderr, "Writeing file: %s\n", rgfilename);
    94   (void) strcpy(rgimage->filename, rgfilename);
    95   WriteImage(image_info, rgimage);
    96   fprintf(stderr, "Writeing file: %s\n", gbfilename);
    97   (void) strcpy(gbimage->filename, gbfilename);
    98   WriteImage(image_info, gbimage);
    99   fprintf(stderr, "Writeing file: %s\n", brfilename);
   100   (void) strcpy(brimage->filename, brfilename);
   101   WriteImage(image_info, brimage);
   102   
   103   image_info=DestroyImageInfo(image_info);
   104   
   105   DestroyExceptionInfo(&exception);
   106   DestroyMagick();
   107   return(0);
   108 }
   109 
  

  {/rimg.c}^e

  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
  

  {/Makefile}^e