I'm trying to blend one vertical line of multicoloured pixels (1px width, 200 px height) on the left, into another vertical line of multicoloured pixels (1px width 200px height) on the right, with a spacing of 500px between them, to create a 500x200 rectangle where each horizontal row of pixels is a smooth gradient between the corresponding end pixels on the left and the right.
Is there a standard way of doing this? I know how to gradient from one pixel into another, but I'm unsure how to do it for a whole set of pixels like this into another set of pixels. I could do it one-by-one but that would be very slow.
I'm using Paint.net; if there is a feature in it that does what I need I'd love to be pointed to it.