I use the following method to get a decompressed uiimage from file system.
However the UIImageView is colored as red when I turn on the color blended
layer, even though the UIImageView is set to Opaque.
The images on file system don't have alpha channel. I tried set
CGContextSetAlpha(bitmapContext, 1), but still has blended layer.
Anyone know how to remove alpha channel when using CGContextDrawImage?
- (UIImage *)decompressedImage
{
CGImageRef imageRef = self.CGImage;
CGRect rect = CGRectMake(0.f, 0.f, CGImageGetWidth(imageRef),
CGImageGetHeight(imageRef));
CGContextRef bitmapContext = CGBitmapContextCreate(NULL,
rect.size.width,
rect.size.height,
CGImageGetBitsPerComponent(imageRef),
CGImageGetBytesPerRow(imageRef),
CGImageGetColorSpace(imageRef),
kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Little
);
// kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Little are the
bit flags required
// so that the main thread doesn't have any conversions to do.
CGContextDrawImage(bitmapContext, rect, imageRef);
CGImageRef decompressedImageRef =
CGBitmapContextCreateImage(bitmapContext);
UIImage* decompressedImage = [UIImage
imageWithCGImage:decompressedImageRef
scale:[[UIScreen
mainScreen] scale]
orientation:UIImageOrientationUp];
CGImageRelease(decompressedImageRef);
CGContextRelease(bitmapContext);
return decompressedImage;
}
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