[magick-users] MagickTrimImage() problem/bug?

[Christian Magnusson]

Hi there,

 

I have tried to create an application which is supposed to download TV-guide
images, and later trim, crop and resize them.

 

It seems to be some problem with the MagickWand-object after I have
successfully called MagickTrimImage(). If the image was trimmed to a smaller
size, MagickCropImage() returns a malformed image.

 

Should be MagickWand be updated in some way after MagickTrimImage() is
called?   I have seen some convert scripts which call "+repage", but are
there any similar functions that should be used?

 

Can anyone give me some hints if it's a bug in ImageMagick, or if I should
try some other method.

 

/Christian

 

BTW: I have used ImageMagick-6.4.3-8.tar.gz during my tests

 

-----------------------------------------------

 

#include <stdio.h>

#include <stdlib.h>

#include <math.h>

#include <wand/MagickWand.h>

 

/*

This example describes that MagickCropImage() fails after MagickTrimImage
has been called (and trimmed the images to a smaller size)

Compile with:

  # gcc -g `MagickWand-config --cflags --cppflags` -o convert_bug
convert_bug.c `MagickWand-config --ldflags --libs` -Wl,-rpath,/usr/local/lib

 

 

  # wget http://xmltv.tvsajten.com/chanlogos/sport2.viasat.se.png

  # wget http://xmltv.tvsajten.com/chanlogos/tv3.viasat.se.png

  # wget http://xmltv.tvsajten.com/chanlogos/hits.canalplus.se.png

  

  (This first example works since the trimmed image has the same size)

  # ./convert_bug tv3.viasat.se.png

  original size w=100 h=100

  trimmed image to w=100 h=100

  Try crop image to w=50 h=100

  cropped image to w=50 h=100

  

  (This example fails and results into a 1x1 image)

  # ./convert_bug hits.canalplus.se.png

  original size w=100 h=100

  trimmed image to w=99 h=12

  Try crop image to w=49 h=12

  cropped image to w=1 h=1

  

  

  (This example fails and results into a 50x34 image (instead of 50x56))

  # ./convert_bug sport2.viasat.se.png

  original size w=100 h=100

  trimmed image to w=100 h=56

  Try crop image to w=50 h=56

  cropped image to w=50 h=34

  

*/

 

 

#define ThrowWandException(wand) \

{ \

  char \

    *description; \

 \

  ExceptionType \

    severity; \

 \

  description=MagickGetException(wand,&severity); \

  (void) fprintf(stderr,"%s %s %lu %s\n",GetMagickModule(),description); \

  description=(char *) MagickRelinquishMemory(description); \

  exit(-1); \

}

 

int main(int argc,char **argv)

{

  MagickBooleanType status;

  MagickWand *src_wand;

  

  if (argc != 2) {

      (void) fprintf(stdout,"Usage: %s image\n",argv[0]);

      exit(0);

  }

 

  MagickWandGenesis();

  src_wand=NewMagickWand();

  status=MagickReadImage(src_wand,argv[1]);

  if (status == MagickFalse)

    ThrowWandException(src_wand);

  printf("original size w=%d h=%d\n", MagickGetImageWidth(src_wand),
MagickGetImageHeight(src_wand));

 

  /* Trim the image and remove border */

  status = MagickTrimImage(src_wand,10);

  if (status == MagickFalse)

        ThrowWandException(src_wand);

  printf("trimmed image to w=%d h=%d\n", MagickGetImageWidth(src_wand),
MagickGetImageHeight(src_wand));

 

  /* crop the left part of the image */

  printf("Try crop image to w=%d h=%d\n", MagickGetImageWidth(src_wand)/2,
MagickGetImageHeight(src_wand));

  status = MagickCropImage(src_wand, MagickGetImageWidth(src_wand)/2,
MagickGetImageHeight(src_wand), 0, 0);

  if (status == MagickFalse)

        ThrowWandException(src_wand);

  printf("cropped image to w=%d h=%d\n", MagickGetImageWidth(src_wand),
MagickGetImageHeight(src_wand));

  

  status = MagickWriteImages(src_wand,"new.png",MagickTrue);

  if (status == MagickFalse)

        ThrowWandException(src_wand);

 

  src_wand = DestroyMagickWand(src_wand);

  MagickWandTerminus();

  return(0);

}