Hi all,
attached is what I ended up getting to work.
#1. loading the video as rgb indeed messes up how pix_chroma_key works, I can't really describe how, but I had to make sure the videos were loading as yuv for it to work at all. Teresa, on OSX this is the default so don't worry about it.
#2. Chris's 128, 50,50 value for the RGB 0,240,0 seems to work, but where the heck did that number come from??
#3. I had to use a high range, about 80, but I think thats because of antialiasing between the green-screen and the figure.
So it looks good!
I can't do a checkout from sourceforge gem cvs this morning, but based on Johannes's new abstractions, I'd like to volunteer to make a keying color-picker. Maybe something that shows your video, allows you to click on a spot, and then feeds that into pix_chroma_key. Maybe even a range of pixels could be chosen.
I think the only way to get the pixel values is pix_dump right? Does it support dumping YUV?
Thanks all for your help.
.b.
On Wed, April 26, 2006 1:03 am, Teresa Ascencao said:
thanks so much for all that you have been helping me with! I really appreciate it.
teresa ascencao www.tascencao.com 416-929-6854
On 25-Apr-06, at 3:07 PM, Mathieu Bouchard wrote:
On Tue, 25 Apr 2006, chris clepper wrote:
On 4/25/06, B. Bogart ben@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).
_ _ __ ___ _____ ________ _____________ _____________________ ... | Mathieu Bouchard - tél:+1.514.383.3801 - http://artengine.ca/matju | Freelance Digital Arts Engineer, Montréal QC Canada
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B. Bogart