advice needed for working with green screens

[Eric5]

I've been using (or attempting to use) AP to remove the background green screen from several objects I photographed.  I used plenty of lighting and the screen appeared as uniform as possible.  However, AP doesn't seem to be able to completely eliminate the screen and I find myself taking a lot of time trying to remove all the green.  I've used several of the selection tools.  I thought at first the best one might have been to select sample color (green) and then remove, but I found that a much fainter green remained and this caused fringing around the object.  So far, the best method I've found is to use the freehand tool and carefully trace around the object, then refine, but this takes a lot of time.  When I used to work with video programs, they had screen keyers and it was basically a one shot deal with threshold manipulation and I could extract the object with excellent results in a couple of minutes... with AP, this is taking me an hour or more for the best selection. 

Any advice would be welcomed!  Although I can get the results I want, it is taking a lot of time and I don't think it should.  Thanks in advance. 

[stokerg]

Hi Eric5,

You could try using the selection brush, with Snap To Edges enabled on the context toolbar, to select the green and then delete it.  That worked on a sample image i've downloaded.  The select sampled colour gave me very mixed results and i'm not entirely sure why.  Would you be able to either attach a sample image or upload one to our Dropbox here and i'll see if i can offer further advise  

[Eric5]

Thanks, but I already tried both of those (selection brush and sampled color).  Although sampled color seemed to show fastest results that was not the case as it didn't seem to get all the colors.  Two applications were actually needed to finally achieve a good result.  Just takes too much time.  The selection brush gives the best results but takes a lot of time.  I guess for now I will continue using the brush.  Too bad there's not a chroma key or similar built in for such tasks.  Using such a keyer for video makes an hour job a 2 minute one.

[v_kyr]

I sometimes use CutOut which supports chroma key, green and blue screen handling for such tasks.

[R C-R]

Have you tried using the Flood Select ("Magic Wand") Tool set to a very low tolerance with "Continuous" ticked? If the background screen really is nearly uniform, with no colored light reflected back onto the foreground object & no shadows, it should be quick & easy to get all the screen color & nothing else selected.

[Eric5]

I put a separate light on the green screen today and tried some more tests.  The green did remove much easier with the flood select tool, but the amount of fringing along the edges of the sample increased, as well as the amount of green within the sample.  I tried using the defringe filter and selected the fringe color (mainly white), but couldn't get it to remove.  Not sure what else I could try to defringe.  I read a tip about using the "minimum filter" which I tried in various amounts, but it took away too much of the object as well.   I also tried a highlights only burn along the edges, but this still ended up darkening the remaining edge too much.    

Now this is just my opinion, but whoever said green screening was the way, at least for digital imagery, may have been wrong.  I have had nothing but issues tackling imaging this way, as opposed to video where I had little, if any, issues.  Therefore, I usually avoid imaging this way, but recently I have had time to try experimenting with the technique, and to try improving upon it, in the event I need to use it more in the future.  

 

[R C-R]

Just now, Eric5 said:

The green did remove much easier with the flood select tool, but the amount of fringing along the edges of the sample increased, as well as the amount of green within the sample.

If you started by clicking & dragging on some part of the green screen in the image with the "Continuous" option ticked, no part of the green in the sample should have been selected unless there was a close color match to the screen green along some edge of the sample & the tolerance setting was too high to avoid selecting both.

If the sample edges do not appear to be a close match to the screen green, zoom in along an edge to look for green light reflected from the screen onto the edges. This is usually caused by a combination of the sample being too close to the screen & not enough white light illuminating the sample from all sides.

Short of reshooting the sample with more effective lighting, the only way to fix this is by refining the selection, which can be tedious.