iOS save combined image

Question

I´ve created an draw module, where i am able to draw over an background image. The "drawings" are an transparent PNG, and i combine it when ill save the image.

But the problem here is that the contrast is sometimes bad to see (see image below).

Before (on paint mode):

After (when ill multiply both images):

(hard to see any yellow).

I multiply both images with:

  UIGraphicsBeginImageContextWithOptions(size, false, 0.0)
  bottomImage!.draw(in: CGRect(x: 0,y: 0,width: size.width, height: size.height))
  topImage!.draw(in: CGRect(x: 0,y: 0,width: size.width, height: size.height), blendMode: CGBlendMode.multiply , alpha: 1.0)
  combinedImage = UIGraphicsGetImageFromCurrentImageContext()
  UIGraphicsEndImageContext()

Any ideas how can i get better colors?

Answer 1

Cut the part about the blend mode. Just draw the "painting" ( topImage ) directly onto the background ( bottomImage ).