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make background transparent instead of white

Mar 31, 2014, 03:52
Post: #1
make background transparent instead of white
I guess this is a beginner question. I've actually image edited for years, mainly with Ulead PhotoImpact and some with Photoshop. I did the bulk of my work in PhotoImpact and just used Photoshop for what I could not do in PI. Now PhotoImpact has been abandoned and I've dumped Windows as my OS in favor of Kubuntu Linux. That's why it would be great for me to build up my skill in Gimp and not need those Windows-based programs.

So here's what I'm doing. I'm editing an image to be used in LibreOffice Writer as an icon. LibreOffice in Kubuntu uses 26x26 PNG files for icons. I had set up an image, but it looked stupid in LO Writer because of its white background. I wanted to take that image and simply replace everything white with clear – make it transparent. I found a cool Youtube tutorial on the subject, which instructed me to do this:

Layer ==> Transparancy ==> Add Alpha Channel

click Magic Wand Tool (aka Fuzzy Select Tool), then click on white space

This worked brilliantly so far. However there were still some white spots. The tutorial advised: “Use eraser tool to erase remaining white parts that didn't go transparent yet.” I've tried that, but it does not respond. It probably has to do with however Gimp works its layers, which I have not mastered yet. I remember layers were very different in PhotoImpact and Photoshop. Here's a screenshot of the image in Gimp, magnified so that you can see. It's only 32x32, which I mistakenly thought was LO Writer's needed size (it's actually 26x26).

[Image: Rot_Casescreenshot.png]
image hosting free

Anyway, it would be great if I could remove those final white specs and replace them with clear. I have other images I want to do the same in.
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Mar 31, 2014, 04:44
Post: #2
RE: make background transparent instead of white
Hi, and welcome.
Have a read of this topic.
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Mar 31, 2014, 06:49 (This post was last modified: Mar 31, 2014 06:50 by iForStyle007.)
Post: #3
RE: make background transparent instead of white
If the colors are clean-solid and there isn't any white in it besides the background you can use the "color to alpha" filter.

Colors > Color to alpha
- Click the color box in the "color to aplha" window, pick white for your image (of all blue, black & white,) click ok

For more distorted/not pure solid images (for example if some of those pixels are light grey:
1. Layer > Transparency > Add alpha chanel
THEN,
2. Fuzzy select the background(white)
3. Select > Invert... (to invert to select the blue & black)
4. Select > shrink...
- 2 to 3 pixels (or more) , click ok
5. *optional step* Select > Feather... (to smooth edges after you delete the background)
6. After you shrink the selection to a little smaller than the colored edges:
- Select > invert (to reselect the background; white)
7. Push delete to clear all the white.

"In order to succeed, your desire for success should be greater than fear of failure." BC
[Image: 29uocaf.png]
iFS007 tut vids on YT ~ auto color B&W landscape tut
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