In 30 Days to Learn Photoshop, Photoshop

How Does Quick Selection Tool in Photoshop Works?

Now the question is that how does it work? How does it automatically detect edges?

If I go to the proper explanation, I need to write the whole mathematical algorithm here. I am certainly not going to do that. Instead I can explain it in simpler words. What Quick Selection Tool does is that it measures the contrast among the adjacent pixels. If there’s a huge change in value, it’ll know by itself that an edge is present out there.


Fig. 4

Let’s understand this with the help of Fig. 4. Suppose I am dragging my cursor from the baby’s right hand towards his left hand. I am making sure that my cursor doesn’t cross the baby’s body. While I am dragging my mouse, Photoshop, in the background, calculating the difference in the RGB values of the nearby pixels. If there’s a huge jump, Photoshop knows that there’s an edge present out there. For example the RGB values of skin color is quite different than the RGB values of the white background.

Vaibhav Sharan
A man who is curious, thrifty, and learner. Entrepreneurship flows in his blood. Ardent follower of BATMAN. Nothing is abstruse if one has strong will power. Check out my BRAND NEW website: I Innovate Magazine.
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