Re: Trouble with using MagickGetSamplingFactors API

Hi Bob:
      I am so Sorry , I didn't describe my ploblem exactly.  I just want to strip the input image , and not to change the sampling factor and quality of the input image.

The test pseudo code like that:
***********************************************************************************
int main(int argc, char *argv[])
{
    MagickWand *wand = NULL;
    char *ptr_quality = NULL;
    char *p = NULL;
    register long number_factors = 0;
    double sampling_factors[3] = {0.0} ;
    char *ptr_sampling_factor = NULL;

    wand = NewMagickWand();
    MagickReadImage(wand, argv[1])

    ptr_sampling_factor = MagickGetImageAttribute(wand, "JPEG-Sampling-factors");
    for (p = ptr_sampling_factor; p != (char *) NULL; p = strchr(p,',')) {
        while (((int) *p != 0) && ((isspace((int) ((unsigned char) *p)) != 0) ||(*p == ','))) {                   
        p++;                                                                                                  
        }                                                                                                         
        sampling_factors[number_factors]=atof(p);                                                                 
        number_factors++;                                                                                         
    }                                                                                                             
    MagickSetSamplingFactors(wand, number_factors, sampling_factors);

    ptr_quality =  MagickGetImageAttribute(wand, "JPEG-Quality");
   MagickSetCompressionQuality(wand, strtoul(ptr_quality, NULL, 10));

   /* Note : It didn't work by using this method to set quality
    MagickSetImageAttribute(wand, (const char *)"JPEG-Quality", (const char *)ptr_quality);
  */

    MagickStripImage(wand);

   MagickWriteImage(wand, argv[2]);
   DestroyMagickWand(wand);
   return 0;
}
********************************************************************************************************************
Thank you .



------------------ Original ------------------
From:  "Bob Friesenhahn"<[email protected]>;
Date:  Wed, Jul 3, 2013 10:17 PM
To:  "google"<[email protected]>; 
Cc:  "graphicsmagick-apis"<[email protected]>; 
Subject:  Re: [GM-apis] Trouble with using MagickGetSamplingFactors API



On Wed, 3 Jul 2013, google wrote:

>        Thank you so much for your reply.
>        I had sovled my problem. And I have another problem,  when I call  MagickStripImage API to
> strip the image,  I got a new  image  which size was  larger than  input image's , I can't explain
> it. (Note: the two images have the sampling factors and quality. )
> Pseudo code like this:
> 
> 1.new MagickWand  object;
> 2.read input image
> 3.get the sampling factor and quality
> 4.set the sampling factor and quality
> 5.call MagickStripImage() to strip the image
> 6.write to output image.

We would be able to understand this issue better if you tell us what 
the original parameters were (sampling factor and quality) and the new 
parameters you used.

Bob
-- 
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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