How to Use an Alpha Channel Mask for Making Selections in Photoshop

In this video we will be learning how to make an alpha channel mask in Photoshop which can help us in making selections in complex subjects like hair strands and thin branches of trees. Here’s the video:

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This video is from our Master Selections in Photoshop course, which has 36 videos and 6 hours of content. You can see the details of the full course by using the link below:

Master Selections in Photoshop course

Video Summary

In this Adobe Photoshop tutorial, Creative Pad Media demonstrates how to use Channel-based selections to create highly accurate masks for complex objects like trees and hair, which automated tools often struggle with.

Key Steps to Create an Alpha Channel Mask:

• Identifying Contrast: Instead of using the Layers tab, switch to the Channels tab [00:13]. Cycle through the Red, Green, and Blue channels to find which one offers the highest contrast between your subject and the background. For landscapes with blue skies, the Blue channel is typically the best choice [01:47].
• Creating a Duplicate: Never work on the original channel, as this will alter the colors of your image [04:51]. Right-click the channel and select Duplicate Channel (e.g., “Blue copy”) to work on a safe copy [05:18].
• Enhancing the Mask: Use Levels (Ctrl+L) to darken the darks and brighten the whites in your duplicate channel [06:07]. The goal is to make the background (sky) pure white and the subject (trees) pure black. You can also use a black brush to manually fill in any light areas within the subject to ensure a solid selection [08:34].
• Applying the Selection:
  1. Hold Ctrl/Cmd and click on the duplicate channel thumbnail to load the selection [09:32].
  2. Return to the Layers panel and click the Add Layer Mask icon.
  3. If the mask is backward (selecting the sky instead of the tree), simply click on the mask and press Ctrl/Cmd + I to invert it [10:35].
• Adding a New Sky and Reflection:
  • Drag in a new sky image and place it below your masked layer [11:04].
  • To make it realistic, you can flip the sky vertically and use a low-flow brush on the mask to “paint in” a subtle reflection on the water [15:59].