I'm doing a job that includes hundreds of simple photos on white backgrounds. Some of them have no shadows and so I can remove the background using the 0-255 slider from Layer Style:
However, some of them, like this one, have a shadow, and I can't use that technique because by the time I've slid it far enough to the left to remove the shadow I've also started turning portions of the image transparent.
I don't actually need a transparent background. I'm printing these on white paper. I remove the background just so there isn't a ghostly rectangle around the image. In other words, the "white" of some of these backgrounds shows up as a very, very light gray in the proof.
In the example above, you can see that it would be very tedious to do a careful selection to allow total erasure of the background.
Is there a way I could blend transparency from the outer edges of the photo rectangle inward, so that if there is a light gray cast to the "white" of the photos it transitions seamlessly to the white of the paper?
I am not a fan of Blend If. If your backgrounds are good enough to use it, then they will be suitable for other, better, methods. What you need is flexability.
There are a few tools that will help, like painting with a big soft brush with white, and brush mode set to Overlay. That will clean up the off white areas. Make the best selection you can of the background. Invert that selection and add a layer mask. You can now use other methods to clean up the layer mask.
You can use the same trick with the brush set to Overlay on the mask by Alt clicking the mask to open its alpha channel full screen, and painting with white or black to reinforce masked and unmasked areas. You can use the pen tool on nice hard lines, or the brush (set to normal again) together with the shift key to clean up straight lines.
It sounds like a bit of work, but it really shouldn't take too long with each image, and if that's what you have to work with, you don't have a lot of options.
I'm guessing that you know you can split the Blend If sliders by holding down the Alt(Opt) key to get a softer transition? I still don't like Blend If though.