I have two sprites that are essentially identical other than the top and middle part. One has a red top and one has a green top. Both have a layer of shading on top that takes over more of the red/green colour as the 4 animation animates. The red sprite looks great, but something feels off with the green sprite. Both sprites are essentially identical. I used GIMP's Colour Map > Swap to change the green to red for each level. I believe the problem is that the green I'm using as a base is too far off the shading colour. Previously it looked too close to the shaded colour so I swapped it for a darker green. Does this sound like it might be the problem - could colours too far apart cause something to appear jerky?