Resize Animated Gif File Without Destroying Animation

Resize animated GIF file without destroying animation

if you have imagemagick access, you can do this:

system("convert big.gif -coalesce coalesce.gif");
system("convert -size 200x100 coalesce.gif -resize 200x10 small.gif");

this is most likely possible with the imagemagick plugin if you don't have system() access

NOTE: this may create a larger filesize though a smaller dimensions image due to coalescing essentially deoptimizing the image.

UPDATE:
If you don't have ImageMagick access, you should be able to use a combination of the following steps to resize an animated gif (assuming you have GD access):

1. Detect if the image is an animated gif: Can I detect animated gifs using php and gd? (top answer)
2. Split the animated gif into individual frames: http://www.phpclasses.org/package/3234-PHP-Split-GIF-animations-into-multiple-images.html
3. Resize the individual frames: http://www.akemapa.com/2008/07/10/php-gd-resize-transparent-image-png-gif/
4. Recomposite the frames into an animated gif again: http://www.phpclasses.org/package/3163-PHP-Generate-GIF-animations-from-a-set-of-GIF-images.html

This is definitely much more intensive than the ImageMagick route, but it should be technically possible.

If you get it working, please share with the world!

How to resize gif with standard php functions without losing the animation

It is possible to resize an animated GIF using GD (what you call "standard PHP").

You need to split the image into individual frames, resize them and then put everything back together.

You can see a more detailed explanation here.

However, I would really suggest you to use imagick, since it's easy to install and much easier to use for advanced tasks like this.

EDIT This is the relevant part from the answer I linked above:

If you don't have ImageMagick access, you should be able to use a
combination of the following steps to resize an animated gif (assuming
you have GD access):

1. Detect if the image is an animated gif: https://stackoverflow.com/questions/280658/can-i-detect-animated-gifs-using-php-and-gd
   (top answer)
2. Split the animated gif into individual frames: [http://www.phpclasses.org/package/3234-PHP-Split-GIF-animations-into-multiple-images.html][2]
3. Resize the individual frames: [http://www.akemapa.com/2008/07/10/php-gd-resize-transparent-image-png-gif/][3]
4. Recomposite the frames into an animated gif again: [http://www.phpclasses.org/package/3163-PHP-Generate-GIF-animations-from-a-set-of-GIF-images.html][4]

How to resize animated gif file using imagemagick without destroying animation using C#?

I think you have to extract every single frame from the gif first, resize every single frame and then put it back together.

Edit: like this? Not tested nor builded...

int maxFrames=32;
ImageMagickObject.MagickImage imgLarge = new ImageMagickObject.MagickImage();  

// first extract all frames from gif to single png files
for(int frame=0; frame<maxFrames;frame++)
{
   object[] o = new object[] { String.Format(strOrig+"[{0}]", frame)
       ,  String.Format("tmp{0}.png", frame) };
   imgLarge.Convert(ref o);    
}
// resize every single png files
// add resized filenames to stringbuilder
StringBuilder filenames = new StringBuilder();
for(int frame=0; frame<maxFrames;frame++)
{
   object[] o = new object[] { String.Format("tmp{0}.png", frame)
                , "-resize"
                , size 
                , "-gravity"
                , "center"
                , "-colorspace"
                , "RGB"
                , "-extent"
                , "1024x768"
                , String.Format("tmp-resized{0}.png", frame) };
   filenames.Append(String.Format("tmp-resized{0}.png", frame));
   filenames.Append(Environment.NewLine);
   imgLarge.Convert(ref o);    
}
// write resized filenames to file
File.WriteAllText("tmp-resized-files.txt", filenames);
// create resize animated gif based on filenames in the tmp-resized-files.txt
   object[] o = new object[] { "@tmp-resized-files.txt"
       ,  strDestNw };
   imgLarge.Convert(ref o);    

Imagemagick animator keeps resizing my images when making gif

Try repaging your images after you open them so they forget any previous virtual canvas sizes:

convert *95w*.png +repage -delay 30 -loop 0 anim.gif

Resize gif file without distortion with Rmagick and Carrierwave

Finally I solved the issue but the resultant GIF file is pretty big, it goes from 500 kb to 4 MB aprox.

process :fix_resize_issue_with_gif

def fix_resize_issue_with_gif
  if file.extension.downcase == 'gif' && version_name.blank?
    list = ::Magick::ImageList.new.from_blob file.read

    if list.size > 1
      list = list.coalesce
      File.open(current_path, 'wb') { |f| f.write list.to_blob }
    end
  end
end

PNG-Preview of animated GIF with ImageMagick is distorted

In Imagemagick, if you want a preview image for all formats including gif and want just the first frame of the animation for the preview, then just add [0] to the filename, such as animation.gif[0]. This will take the first frame of the animation and the only frames of the other formats such as JPG and PNG that only allow one frame. The appended [0] does not hurt the other formats.

So use

image.suffix[0] in place of just image.suffix

for generating a single image preview

How to resize and save gif file with Magick++ without animation loss

I found a solution! Thank you MofX for right direction!

   Geometry newSize = Geometry(m_newSize.width(), m_newSize.height());
   newSize.aspect(true); 
   list<Image> frames;
   readImages(&frames, imagePath.toStdString());
   for (auto& image : frames)
        image.resize(newSize);
   writeImages(frames.begin(), frames.end(), newImagePath.toStdString());

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