Bug #48052 for GD: GD::Image->_image_type does not recognise jpeg image if it starts with a comment tag

The code checking the type of a image is the following: sub _image_type { my $data = shift; my $magic = substr($data,0,4); return 'Png' if $magic eq "\x89PNG"; return 'Jpeg' if $magic eq "\377\330\377\340"; return 'Jpeg' if $magic eq "\377\330\377\341"; return 'Jpeg' if $magic eq "\377\330\377\355"; return 'Jpeg' if $magic eq "\377\330\377\356"; return 'Gif' if $magic eq "GIF8"; return 'Gd2' if $magic eq "gd2\000"; return 'Xpm' if substr($data,0,9) eq "/* XPM */"; return; } But there a many other values for the 3. and 4. byte. After the magic, the JFIF-Headers starts. And GD is only happy if the image _header_ starts with: 340: JFIF tag 341: EXIF data 355: A generic pointer 356: A generic pointer / copyright entry see also: http://de.wikipedia.org/wiki/JPEG_File_Interchange_Format But there are other tags which are valid i guess. I used ffmpeg to capture a frame from a video sequence and that jpeg has a comment field as a first tag (0xfe) so that GD doesn't recognize it. (See the attached file) Why do you check the 3. and 4. byte at all? Isn't checking the magic enough? If you think its necessary, you should at least add the comment tag as a valid tag i think.