TECHNIQUE: How to Use Channels to Remove a Background

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*Technique
TECHNIQUE: How to Use Channels to Remove a Background
By Zee Helmick 2007
Jun 13, 2007, 01:06

BASIC: How to Use Channels to Remove the Background in Paint Shop Pro X

Removing the background from some photos can be tricky. Often, using the Selection tool or Magic Wand isn’t enough. Splitting the image channels to RGB can help you isolate your subject and remove the background. This tutorial will show you how to split and use channels to remove the background of an image in Paint Shop Pro X.

1. Let’s begin by opening an image and duplicating it (Shift+D). Close the original photo. For this example, I’m using an image from Dover Clip Art Angels. (This method is very helpful when attempting to remove the background from clip art.) This artwork has a white background that I want to remove.

2. Split the channels to RGB by clicking on Image > Split Channel > Split to RGB.

3. Three additional windows will open for each of the channels (red, green and blue). Select the image that has the most contrast between the subject you want to isolate and the background. In this example, it appears that the Blue channel has the most contrast. (The channel you choose will depend on your image.) Close the other two channels since we won’t need them.

4. Let’s increase the contrast even more by adjusting the values in the Highlight/Midtone/Shadow window. Click Adjust > Brightness and Contrast > Highlight/Midtone/Shadow (or type Shift+M). Use the sliders to adjust the image so that your image is as dark as possible.

5. Click OK.

6. If necessary, increase the contrast even more by adjusting the Brightness/Contrast. Click on Adjust > Brightness and Contrast > Brightness/Contrast (or type Shift+B). Experiment with values until your image is completely black with a white background.

7. Click OK.

8. Notice the small white pixels of white? Let’s paint those specks out with black. Be sure to zoom in if necessary.

9. Invert the image by clicking on Image > Negative Image.

10. Click on Effects > Edge Effects > Erode. This step will help remove more of the white background on the very edge of your image.
11. Keep this image open and switch back to your original photo.

12. You’re now ready to remove the background. Click on Layers > New Mask Layer > From Image. Choose the channel that you just created as the Source window. Create mask from Source luminance.

13. Click OK. The background should now be masked.

14. Click on Layers > Merge > Merge Visible.

15. If the edges of your image seem to be a little jagged, click on the transparent area with the Magic Wand tool and go to Selections > Modify > Feather (or type Ctrl+H). Enter a value in the field and hit OK.

16. Hit the Delete key on your keyboard once or twice to soften the edges of your image.

17. You can now copy this image and paste it onto the background of your choice.