Make Image Transparent in Gimp
Make your paper drawing or photo background transparent for use in 2D or 3D animation
This can be done in several ways. The method discussed here work best for high contrast images with distinct contours, like black drawing on white paper or a solid shape against an even coloured background. The first example down below shows a greyblack pencil drawing on white paper . (Tips for more complex backgrounds will be added later.) If you have a lot of images, more than 10 or so, the method for Blender is recommended (see Blender section), with that method you can save multiple images at once. With this Gimp method you need to save each image separately.
Preparing: If you like to have a standard size or even size of your image, like 400x400 or 1024x1024, then create such an image first and then drag or open the images to this base image. This might be a good idea if you have paper drawings that a scanner did not save exactly with the same size. To create a new image, choose File - New, enter the resolution size you’d like.
First, as a help, create a completely black layer and a completely white layer and move them to the bottom, you can turn these layers on and off later on to view spots that you’d like to get rid of. To do a black layer, make the active foreground Color black, click on the color icon to the upper left, drag the color so all the values show 0.0 or HTML notation says 000000.
Before we try to remove a color, we may need to enhance the contrast of the colors.
Another Method to remove the background is to choose the Fuzzy Select Tool or the similar “Select by Color”, both from Menu Tools - Selection Tools,. These are good tools for removing more complex, difficult backgrounds. There are a lot of settings you can try here but try to start with "Select by Composite". Make sure your image has an alpha layer. If not, click on Layer - Transparency - Add Alpha Channel. (If no alpha channel exists the area you remove will get a solid background colour.) Click on the color you want to remove. An area will be selected. Click on delete to remove. Experiment with Threshold. You may need to repeat the process several times and click on different nuances of the image to clean it up.