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The problem with this is that not all logos are at the top. In fact, in Australia, all logos are found in the bottom right. With my sampling pattern, on all the frames I have looked at, you sample at most 2 pixels from the logo (and only if it is very wide, your logos seem much wider than ours) so it is easy to discard logo sections, even with very simple threshhold/brightness testing.I have thought of another way to help refine the guesses. In frames such as your 2film3 frame it is easy to discover the vertical bounds (how high the frame is) and the right bound, but the left bound is difficult because of low brightness. However, you can take advantage of the fact that frames are (in every case I have ever seen) always pretty much centred horizontally (not necessarily vertically). So if the distance from the left of the screen to the bound is very different to that of the right side of the screen to the bound (or either are undecidable from the current frame) you can just take the smallest distance and use that for the other side. This allows you to get much better frames in general.I also have an easy way of picking up the tails on the 'g' and the like in subtitled frames, as they are easily missed at the moment. If you are interested I can elaborate.It is up to you how you go about it, though, as you are the one doing the hard stuff like working on the transform filter.
The problem with this is that not all logos are at the top. In fact, in Australia, all logos are found in the bottom right. With my sampling pattern, on all the frames I have looked at, you sample at most 2 pixels from the logo (and only if it is very wide, your logos seem much wider than ours) so it is easy to discard logo sections, even with very simple threshhold/brightness testing.
I have thought of another way to help refine the guesses. In frames such as your 2film3 frame it is easy to discover the vertical bounds (how high the frame is) and the right bound, but the left bound is difficult because of low brightness. However, you can take advantage of the fact that frames are (in every case I have ever seen) always pretty much centred horizontally (not necessarily vertically). So if the distance from the left of the screen to the bound is very different to that of the right side of the screen to the bound (or either are undecidable from the current frame) you can just take the smallest distance and use that for the other side. This allows you to get much better frames in general.
I also have an easy way of picking up the tails on the 'g' and the like in subtitled frames, as they are easily missed at the moment. If you are interested I can elaborate.
It is up to you how you go about it, though, as you are the one doing the hard stuff like working on the transform filter.