[GEM-dev] pix_chroma_key not acting as I expect?

[Mathieu Bouchard]

On Tue, 25 Apr 2006, chris clepper wrote:

> On 4/25/06, B. Bogart <ben at ekran.org> wrote:
> >  I still could not get pix_chroma_key to key on "value 16,16,16" remember
> > our green is 0,240,0 not 0,255,0. (which I guess is YUV 0,0,0)? what
> > should the YUV range be like for this video?
> I may have bungled some of the code in that object.  Try 128, 50, 50
> and a range of 30 or so for a green background.  I was able to key out
> a fairly typical green screen with that.

there's [rgb2hsv], [hsv2rgb], but do [rgb2yuv] and [yuv2rgb] exist yet?

There's [#rgb_to_yuv] and [#yuv_to_rgb] which works for both single pixels
and whole pictures, but they use JPEG-style yuv, which goes 0..255 instead
of the legacy range 16..239 (and such) which are due to NTSC/PAL voltage
specifications. (Both ranges of YUV are in wide use).

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| Mathieu Bouchard - tél:+1.514.383.3801 - http://artengine.ca/matju
| Freelance Digital Arts Engineer, Montréal QC Canada