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strukturag / libheif

libheif is an HEIF and AVIF file format decoder and encoder.
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decode Grid image does not consider width or height is odd number #157

Open hongxiazhang opened 5 years ago

hongxiazhang commented 5 years ago

In function HeifContext::decode_full_grid_image and HeifContext::decode_and_paste_tile_image does not consider when original image width or height is odd number, when odd, for YUV420, one row or col UV is missing.

farindk commented 5 years ago

To make sure that we are talking about the same thing: do you mean that the full image has odd size or each of the tile images?

Odd sizes of the full image should of course be supported. I think I spotted the part of the code that has to be fixed, but I do not have an image to test against. Could you please attach a test image?

I checked the standard whether tile images may have odd sizes and strangely, I could not find any section that says that it is a requirement that the tile images have even size. In my view, having odd sized tiles is a very bad idea because it means that the color sampling grid changes for different parts of the image. I.e. we could only compose the tiled image in some 4:4:4 space or RGB. At the moment, I do not have a good idea how to support this such that it will not lead to false color edges. Hence, I'd prefer to consider this as a bug in the standard :-)

hongxiazhang commented 5 years ago

I mean the full image, for the tile all used 512x512. Here I attached a example image. image-00002485

farindk commented 5 years ago

Something went wrong with your image upload to github. Please have a look. You can also upload the image here: https://nextcloud.struktur.de/s/cwrZ41qozrPFaAg