How can I convert a picture with any color and form to its shape? As an example I attached an input image and desired output. I need to make this conversion with ruby and ruby-vips gem. Generally speaking, I need to fill anything that is not alpha channel with single color.
You can use [ ] to get bands out of an image. Your image is RGBA, so 0, 1 and 2 are R, G and B, and 3 is A.
alpha = image[3]
You can use ranges as well, so eg.:
rgb = image[0..2]
Gets the first three bands. bandsplit breaks an image into an array of one-band images:
r, g, b, a = image.bandsplit
The alpha has 0 for transparent and 255 for solid, and it sounds like you'd prefer the inverse of that. Therefore:
mask = image[3].invert
