Combining 2 or more masks in photoshop
This is another tutorial in my masking series. If this is the first time you are here you will need to start out reading and learning my Masking and removing backgrounds in photoshop tutorial first and then come back here as this tutorial will be building on what you learned there.
Sometimes there are images that are either to low quality or with backgrounds so busy that a one shot channel mask just will not work, and that’s when we pull out the big guns..
Creating multiple masks for different parts of the image and then combining 2 or more masks in photoshop into one finished mask.
Imagine that you are working with an image that is giving you trouble creating a mask in one go with channel masking or calculations. You can get part of the mask but there’s an area where the background and foreground is to close in colors to allow you to dodge and burn and enhance it to separate the foreground from the background.
Now you need to pull out all the tricks you know to create the mask in parts, and then combine the different masked out areas into one finished mask.
First take a stab at getting as much of the mask using channel masking or calculations masking and save that mask. Now try LAB and see if the area that doesn’t work for you in RGB will give you that area and save that as another mask. If that doesn’t work, trace the area with the pen tool, go to the paths palette and click the little icon in the bottom that creates a selection from the path, go back and create a new alpha channel and fill the selection with white. Keep pulling out all your masking tricks until all the parts of the object is selected using multiple masks.
Before going further, you will need to make sure that all the masks are white where the subject you want to mask out are, if not, hit control+i to invert those parts.
Now open up the calculations dialog. In the source 1 channel drop down list select the first mask, in the source 2 channel select the second mask. Now for the magic. Select the screen blending mode and your 2 masks will be combined into one. Only the areas above 50% grey will be combined, and anything below will be discarded, and that gives you a combined mask. If you have more masks to combine, use calculations again, this time selecting the combined mask you just create, and the next part of the mask puzzle until all parts have been combined.
