Hey thanks a bunch Matto to have a look @ those frames ! Although I didn t get everything in details (shame ...) , i understood the colorspace conversion is losing some data as there is no equivalent in RGB.
>Hey, Seb, > >I don't think there is any particular problem with ppmtoy4m/y4mtoppm; > testing with colorbars/whatnot shows that the output of a cycle is > pretty faithful to an input. > >One thing though: in the frame you sent me, about 10% of the pixels > are clipped in the initial conversion to R'G'B' --- these are Y'CbCr > values in the orginal frame which lie outside of the R'G'B' color > cube. When they are clipped (projected/forced into the R'G'B' cube), > they will generally appear brighter (the Y' of the clipped pixel will > be higher than the original Y' value). > >Perhaps this is what is happening? >In other words, this is classic colorspace-conversion lossiness, which > is affecting 10% of the pixels in your frame (with an average shift > of +10 in G for those pixels...). > >(I have no good suggestion for fixing this --- maybe passing the entire > stream through the Y'CbCr->R'G'B'->Y'CbCr process, so that there will > be no visible transition between the frames with 'effects' and those > without? > Did that ... the result is OK but still we feel the difference with the original frames. but well no difference between frames in the video itself that is for sure >Or doing the work in Y'CbCr colorspace [all non-ideal for > a few reasons]. > I was thinking about this option but couldnot find any tool to handle compositing of YUV images or y4m frames.. (i am testing y4merge though...) why would you think this is not ideal anyway ? >Or writing tools which will handle negative R'G'B' > values. Or writing a luma-preserving clipping algorithm....) > > i am afraid this option is not an option to me (for now ... need to understand few things first still ;-) ) Cheers and thanx again Seb >-m > > > > > >------------------------------------------------------- >SF.Net email is sponsored by: Discover Easy Linux Migration Strategies >from IBM. Find simple to follow Roadmaps, straightforward articles, >informative Webcasts and more! Get everything you need to get up to >speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click >_______________________________________________ >Mjpeg-users mailing list >Mjpeg-users@lists.sourceforge.net >https://lists.sourceforge.net/lists/listinfo/mjpeg-users > > > > ------------------------------------------------------- SF.Net email is sponsored by: Discover Easy Linux Migration Strategies from IBM. Find simple to follow Roadmaps, straightforward articles, informative Webcasts and more! Get everything you need to get up to speed, fast. http://ads.osdn.com/?ad_id=7477&alloc_id=16492&op=click _______________________________________________ Mjpeg-users mailing list Mjpeg-users@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/mjpeg-users
