ADDITIONAL SYSTEM INFORMATION :
I was using OpenJDK 16.0.2, but I had also tried to run my program on JRE 8 and it seems to be old problem with
every Java version.

A DESCRIPTION OF THE PROBLEM :
When I try to read animated gif frame by frame, only a first frame has desired size and the rest of frames seems to be cropped by lines with all transparent pixels.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
try the following code:

        int frames_count;
        ArrayList<BufferedImage> anim;
        BufferedImage img;
        
        ImageReader img_reader;
        ImageInputStream img_stream;
        
        img_reader = ImageIO.getImageReadersByMIMEType("image/gif").next();
        img_stream = ImageIO.createImageInputStream(new File("animated-gif-file.gif"));
        img_reader.setInput(img_stream);
        
        frames_count = img_reader.getNumImages(true);
        anim = new ArrayList<BufferedImage>();
        for (int i=0;i<frames_count;i++) {
            img = img_reader.read(i);
            System.out.println("Frame "+i+" width: "+img.getWidth());
            anim.add(img);
        }
      

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
I was expecting to every gif frame (img) has the same size of 32x32 pixels.
ACTUAL -
for my 32x32 gif image (with two frames of animation) it will print in command line:
Frame 0 width: 32
Frame 1 width: 18

Like I have written further frames are cropped by transparent pixels.


FREQUENCY : always