iPhone: Changing CGImageAlphaInfo of CGImage
- by TechZen
I have a PNG image that has an unsupported bitmap graphics context pixel format. Whenever I attempt to resize the image, CGBitmapContextCreate() chokes on the unsupported format
(Error formatted for easy reading):
CGBitmapContextCreate: unsupported parameter combination:
8 integer bits/component;
32 bits/pixel;
3-component colorspace;
kCGImageAlphaLast;
1344 bytes/row.
The list of supported pixel formats definitely does not support this combination. It appears I need to redraw the image and move the alpha channel information to kCGImageAlphaPremultipliedFirst or kCGImageAlphaPremultipliedLast.
I have no idea how to go about doing this.
There is nothing unusual about the PNG file and it isn't corrupted. It works in all other context just fine. I encountered this error just by chance but obviously my users might have similarly formatted files so I will have to check my app's imported images and correct for this problem.
