View Full Version : strange patterns in green screen

10-24-2011, 05:16 PM
greetings, i am having strange patterns showing up in green screen. the shot has been massaged in photoshop so that the green is even. and yet it doesn't cut out the green in either a32 or 64 bit. you guys have been great in the past, what stupid thing am i missing?

10-25-2011, 01:50 AM
We need pictures to better diagnose the problem.


10-25-2011, 02:13 AM
Dithering pattern powered by color space?
You can control Dithering in Effects window, Processing tab.

10-25-2011, 06:29 AM
here's that pic attachment to aid in diagnosis. also included is a reduced size copy of an original. i have tried the dithering switches to no avail. the pattern changes wildly with different resolutions but still no clip.

thanks for your assistance.:bangwall:

10-25-2011, 06:32 AM
So you're using in fresh scene test 1.bmp as background image in Effects window, pressing F9, and receiving green screen.bmp as result?

10-25-2011, 06:40 AM
i am using test 1.bmp as a foreground image, setting foreground clip, high and low colors as: r1 g182 b69 and then pressing f9 and getting green screen.bmp as a result. try it and see what you get. this is confusing.

10-25-2011, 06:46 AM
I got this, repeating every step what you said in previous post in LW v10.1


Foreground Key toggled on, Low & High clip colors the same 1,182,69

10-25-2011, 06:49 AM
But if I open Image Editor and toggle Dithering to something else than Off, I am getting a lot of black dots.

10-25-2011, 06:50 AM
here is another version of what i am getting.

10-25-2011, 06:52 AM
well that's what i want... but this is what i am getting. i tried it on my twin phenom II and got the same thing. i will try it again and let you know. thanks for your efforts.

10-25-2011, 06:57 AM
i have now tried it on my discovery edition of lw 10 and i get the same thing. i need to find someone to pull my hair out, i'm too bummed to do it myself...

10-25-2011, 07:02 AM
I don't see anything in this thread to indicate you have checked your dithering settings, which Sensei is suggesting may be your issue?

10-25-2011, 07:12 AM
sorry, my fault. yes i did go to all available settings including none. 9.6.1 and 10.1
i am still stumped but thanks. something is wrong here. but i don't know what it is or why it's the same on two hardware and software platforms. but i thank you all for your help.

10-25-2011, 09:11 AM
Why are you trying to do this with Green Screen?

If you have "massaged" this image in PS, they you could just as easily set up an Action template to remove the Green altogether and saved it out as an Alpha transparency in TGA32, PS, or PNG formats.

Anyway, I'm no expert on this but, the last image with the thumbnail posted, where it looks like you have a green glow, seems to me that when you set you Low and High values to the same setting means you have a single color with no range outside of that single color. That glow looks like reflected light from the backdrop flooding back onto the subject and there are shades in that area that are outside that zero range you have defined. In keying software I have used this was covered under the "knee" setting. In anycase again this could have been solved in PS with this particular subject it appears by simply turning it into a Greyscale image rather than a color one.

Hope this offers some ideas you find helpful.

Good Luck

10-25-2011, 12:22 PM
thank you so much. these are great suggestions. some of which i am moving on right now as a work around. others just didn't occur to me at all. i cannot overstate how helpful all of you are. such patience with my stupidity.

thank you all sincerely.