Get Pixel color of UIImage

Question

How can I get the RGB value of a particular pixel in a UIImage?

Answer 1

Try this very simple code:

I used to detect a wall in my maze game (the only info that I need is the alpha channel, but I included the code to get the other colors for you):

- (BOOL)isWallPixel:(UIImage *)image xCoordinate:(int)x yCoordinate:(int)y {

    CFDataRef pixelData = CGDataProviderCopyData(CGImageGetDataProvider(image.CGImage));
    const UInt8* data = CFDataGetBytePtr(pixelData);

    int pixelInfo = ((image.size.width  * y) + x ) * 4; // The image is png

    //UInt8 red = data[pixelInfo];         // If you need this info, enable it
    //UInt8 green = data[(pixelInfo + 1)]; // If you need this info, enable it
    //UInt8 blue = data[pixelInfo + 2];    // If you need this info, enable it
    UInt8 alpha = data[pixelInfo + 3];     // I need only this info for my maze game
    CFRelease(pixelData);

    //UIColor* color = [UIColor colorWithRed:red/255.0f green:green/255.0f blue:blue/255.0f alpha:alpha/255.0f]; // The pixel color info

    if (alpha) return YES;
    else return NO;

}