Frame transparent color in animated gif file

[includeh10]

Frames in many animated gif files don't have transparent color, that is, transparent color index of the frames is not valid (Transparent Color Flag is zero). In the case, I guess, the frames use default transparent color : white - rgb=(255,255,255). But I can not find docs on google to confirm it. If you have knowledge about animated gif format, please let me know if my guess is true. BTW: all gifs of this kind found by me have white background, that is why I think there is default transparent color for this kind gifs.

[Chris Losinger]

here is the GIF Spec[^]. there is no default transparent color, AFAIK. typically the rendering code just picks a color like white or black, or the app lets the user choose a color when rendering transparent images, of any format, when there is no background.

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