interpolation blend colors even when fully transparent about opencv HOT 3 OPEN

@asmorkalov
i provided more info about this ussue please reconcider

from opencv.

warpAffine applies interpolation to all channels, including alpha. It means, that alpha value on rectangle border is not strictly 0 or 255.

from opencv.

yes, but the problem is that when the background color is (255, 0, 0, 0) it is interpolating to red even though alpha is 0.

when image background is RGBA (0, 0, 0, 0)

when image background is RGBA (255, 0, 0, 0)

when image background is RGBA (0, 255, 0, 0)

background is fully transparent so it be (0, 0, 0, 0) or (255, 0, 0, 0) or (0, 255, 0, 0) should produce same results, the RGB channels should be ignored when alpha is 0

this wikipedia articles describes this problem
https://en.wikipedia.org/wiki/Alpha_compositing#Comparison
The most significant advantage of premultiplied alpha is that it allows for correct blending, interpolation, and filtering. Ordinary interpolation without premultiplied alpha leads to RGB information leaking out of fully transparent (A=0) regions, even though this RGB information is ideally invisible. When interpolating or filtering images with abrupt borders between transparent and opaque regions, this can result in borders of colors that were not visible in the original image. Errors also occur in areas of semitransparency because the RGB components are not correctly weighted, giving incorrectly high weighting to the color of the more transparent (lower alpha) pixels.

from opencv.