It seems to be an overlay/color to alpha's problem, you would like to remove the yellowish thing which define those straight edges?
if I am right, you are using an image on a layer above to "burn"...? Am I?
If so can you provide us that image that you use to "burn"?
if I am right, you are using an image on a layer above to "burn"...? Am I?
If so can you provide us that image that you use to "burn"?