On Sat, Oct 23, 2021 at 12:53 PM smoothgroove <smoothgro...@gmx.net> wrote:
> Thanks for your clear response, I see the problem. > > I'm wondering if there is any way to somehow lower the threshold for dark > green areas in order to reduce/suppress shadows in the foreground stream? > For example to somehow preprocess the foreground to reduce the contrast of > the green content? > > In general, since there are different applications of chromakey, it would > be > very useful to be able to control the threshold of darker green content > with > a "shadow" parameter to the chromakey filter. > > 1) using for example a brick wall as a background image -> shadow from > foreground image is desired > 2) using a landscape as a background image -> shadow from foreground image > is not desired > I think despill can do that, but need to revisit that. > > thanks, roman > > -----Original Message----- > From: ffmpeg-user <ffmpeg-user-boun...@ffmpeg.org> On Behalf Of Paul B > Mahol > Sent: Sunday, 12 September 2021 20:56 > To: FFmpeg user questions <ffmpeg-user@ffmpeg.org> > Subject: Re: [FFmpeg-user] How can chromakey ignore shadows ? > > On Sun, Sep 12, 2021 at 8:34 PM smoothgroove <smoothgro...@gmx.net> wrote: > > > Using chromakey=0x00ff00:0.24:0.14 > > > > Is there any way to completely knock out the chromakey background, i.e. > > ignorning the lighting level, shadows and structure of the chroma > > background? > > > > In the examples: > > > > - The arm is casting a shadow on the greenscreen which is reflected in > > the result. > > - the face being near to the light automatically causes the chroma > > background to darken, which causes the replaced image to unnaturally > > darken. > > - a fold in the greenscreen fabric shows up in the replaced background > > > > What is required is chromakey being insenstitive to the chroma > > brightness, that is to totally punch out the background. How could > > this be accomplished? > > > > chromakey operates in YUV colorspace and use only U and V component to set > transparency. > And as such it will only set to transparent color some radius around UV > point as can be seen with this command: > > ffplay -f lavfi -i > > color=s=512x512,geq=lum=N:cb="X":cr="Y":a=255,format=yuva420p,chromakey=0x00 > ff00:0.24:0.14 > > Notice how very dark green and very bright green are not set to transparent > color. > _______________________________________________ > ffmpeg-user mailing list > ffmpeg-user@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org > with subject "unsubscribe". > > _______________________________________________ > ffmpeg-user mailing list > ffmpeg-user@ffmpeg.org > https://ffmpeg.org/mailman/listinfo/ffmpeg-user > > To unsubscribe, visit link above, or email > ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe". > _______________________________________________ ffmpeg-user mailing list ffmpeg-user@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email ffmpeg-user-requ...@ffmpeg.org with subject "unsubscribe".