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 thanks, roman -----Original Message----- From: ffmpeg-user <[email protected]> On Behalf Of Paul B Mahol Sent: Sunday, 12 September 2021 20:56 To: FFmpeg user questions <[email protected]> Subject: Re: [FFmpeg-user] How can chromakey ignore shadows ? On Sun, Sep 12, 2021 at 8:34 PM smoothgroove <[email protected]> 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 [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe". _______________________________________________ ffmpeg-user mailing list [email protected] https://ffmpeg.org/mailman/listinfo/ffmpeg-user To unsubscribe, visit link above, or email [email protected] with subject "unsubscribe".
