PNG transparency not blended properly in iPhone app?

Question

This is my first iPhone app in which I am importing images wholesale from Photoshop. Some aren't rendering properly.

The following image is a white button with rounded corners; the transparency overall is being preserved, but the blending from the image to the transparent pixels results in a white edge around each corner:

http://adambossy.com/media/images/white%20corners%20in%20app.png

The corners should look like this:

http://adambossy.com/media/images/normal%20corners%20in%20photoshop.png

I can't find PNG specs outside of those required for the splash screen and icon (72ppi, RGB, 8 bits/channel, etc.) so I am following those. The button image looks fine in my browser against a black background. However, when imported into the app (simulator AND device), it renders incorrectly.

Any ideas?

Answer 1

What type of button are you using?

use a custom UIButton

Answer 2

You might be experiencing problems with the clear color. Also, be aware that Xcode will optimize PNGs by default.