Set background color to transparent
1. Open GIMP (https://www.gimp.org/).
2. Opend an image file File -> Open…
3. Select transparency Layer -> Transparency -> Add Alpha Channel
4. Click a color in the image to activate the transparency process, which make one color to transparent over the image. (A box of Color to Alpha will pop up)
5. Adjusting the Opacity threshold (% of transparency of a selected color).
5.1. Can select another color to make it transparent by changing Color using Color picker in the second row of Color to Alpha.
6. Output the image file File -> Export as…, click Select File Type, then choose PNG image (Must choose .png
file, .jpg
file will not have transparency effect).
7. Rename file, then Export.
Extend the transparent background
1. Open setting Layer -> Layer Boundary Size
2. Adjust Width and Height of image, then adjust offset of image over the layer, then click Resize.
3. Extend content to layer Image -> Fit Canvas to Layers
4. Export