I'm working on a job that includes 100s of shots of paper cups that have white/light blue/light green/yellow/pink/grey graphics. My question is what is the fastest technique to getting these shots cut out?
Here's what I'm doing:
1) Shooting with a blue backdrop
2) Using Quick select. It takes about 30sec to get a tight selection from each shot.
3) Shifting edge by -2 to reduce the spill from the blue screen (the cups are mostly white)
I'm getting a good key this way, but I think there should be a faster way to do it. I've tested white and green backgrounds, the blue works the best. I've tried Color Range selecting, it takes 3 passes to get it right, Quick Selecting is faster and tighter. I've tried 3rd party plugins to key the blue, and the edges of the cups that are blue always end up sloppy.
Well, other than reshooting, it sounds like you are doing what you can.
When I shoot against any key (green, blue, white, black), I always put the object well ahead of the key color, light the object completely separate from the key and always remember even a small backlight for the object to help prevent spill from the background - basically assuming a standard 3-light setup. That doesn't always happen, I know. I do know that the main reason to use green for keying is that the blue channel tends to be noisier than green (there are 2x as many sensors in the green range vs. red or blue and the light info all comes from the green channel). I used to use the Disney Gamma Green from Home Depot for my green - it's far cheaper than key green and works great (used it here: http://holodad.com/ - the hologram scenes and "interior" ship scenes, etc.), but I don't think HD carries the Disney stuff anymore.
I know this is for video, BUT the principles are the same, nonetheless.
Since you are using blue, I suggest selecting the blue, but wait on fine tuning - instead save the selection first, then go to the channels tab and isolate the blue channel. Load the selection and then try selecting just the blue areas OR, if the object is mostly devoid of blue, use the blue channel as your selection, add the saved selection and go from there. You can also try subtracting either the green or red channels, too, then re-adding your prior selection.
Can you post a couple of the photos? I could try them and see what I can do.