On Sun, Aug 15, 2021 at 3:43 PM Paul Buxton <[email protected]> wrote:
> Thanks both. > > I have implemented the algorithm in this paper > > https://www.researchgate.net/publication/275213614_A_New_Color_Correction_Method_for_Underwater_Imaging > > Which basically converts to an L A B (not CIELAB) colorspace, subtracts the > average value of the frame from each pixel and converts back. > > Yes I did put the linearisation /de-linearisation into the filter. Not > applying it produces noticeably incorrect results. Is there instead a way > to tell the filtergraph that the filter expects and outputs linear data? > There is no automated thing yet, but for converting to/from linear use zscale filter. Also if input is 8bit depth I doubt there can be recovered much if there is no red component in video. If input is in float that is completely different story.... > > I can investigate an integer version. > > > On Sun, Aug 15, 2021 at 2:31 PM Paul B Mahol <[email protected]> wrote: > > > On Sun, Aug 15, 2021 at 3:27 PM Nicolas George <[email protected]> wrote: > > > > > Paul Buxton (12021-08-15): > > > > I have my filter working nicely but it is a little slow. I have > > > > parallelised it where possible, but it is still a bit heavy. I am > > > wondering > > > > if there are any optimised implementations/approximations of some > math > > > > functions built in that I should use instead of the standard library > > > > implementations. > > > > Specifically any of > > > > pow() > > > > exp() > > > > log() > > > > > > > > I have done a quick grep of the code but can't see any likely > > contenders. > > > > > > I am not aware we have those. The kind of optimization you can do > > > depends a lot on your use case. Please give a little details. > > > > > > If you want to speed your filter up, the best would be to make it work > > > with integers. It would also allow to make reliable unit tests. > > > > > > > > > If you convert to/from linear light inside filter, that is wrong thing to > > do. > > > > > > > > > > Regards, > > > > > > -- > > > Nicolas George > > > _______________________________________________ > > > ffmpeg-devel mailing list > > > [email protected] > > > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > > > > > To unsubscribe, visit link above, or email > > > [email protected] with subject "unsubscribe". > > > > > _______________________________________________ > > ffmpeg-devel mailing list > > [email protected] > > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > > > To unsubscribe, visit link above, or email > > [email protected] with subject "unsubscribe". > > > _______________________________________________ > ffmpeg-devel mailing list > [email protected] > https://ffmpeg.org/mailman/listinfo/ffmpeg-devel > > To unsubscribe, visit link above, or email > [email protected] with subject "unsubscribe". > _______________________________________________ ffmpeg-devel mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
