A COMPREHENSIVE INTRODUCTION TO
PHOTOSHOP SELECTION TECHNIQUES
Compiled by <<coldbing>>
Have you ever had difficulties making selections and thought there was a better way? Let's
review both quick solutions, and on the other side, comprehensive and details techniques for
making selections. Each approach has its place in your workflow. The more methods you know
how to use, the faster and more effectively you'll move in Photoshop.
SELECTION IN PHOTOSHOP
Photoshop selects pixels based one of the three properties, as shown in the image below:
1. Chroma: is the color of the pixel. Color of a pixel is the level of RGB values and color
based select tools like the Magic Wand. Select by color uses the RGB & percnt; as a
criteria to group pixels based on the set tolerance values.
2. Luma: is a selection based on Illumination levels. Illumination levels are whiteness of the
image, which is nothing but higher values for all the three R, G and B channels.
Photoshop doesn't have a native interface for a Luma based selection, but many existing
tools can be hacked to get a similar result.
3. Masks: are based on spatial position. Pixels are selected and discarded or masked by a
parallel layer bound to corresponding image layer. Masks are grayscale and brightness of
the mask is called an Alpha level, which is the degree of opaqueness of the corresponding
layer pixel. It's also called the Transparency/Opacity channel as in RGBA etc.
A NOTE ON MASKS
In this article, words like Masks and Alpha will be used interchangeably. The process of
transferring images to layer masks will be shown once and then used repeatedly without
explicitly mentioning thereafter.
Open a new image that you want to use as a mask. Double-click the background layer and
create a new layer, which is "Layer 0." Make a new layer, which is "Layer 1," on top of it and fill
with a uniform color, then hide "Layer 1."
Go to "Layer 0" a