How can I get the specify point's color in the UIImage?

Question

For example, I have a UIImage, I would like to know the image position (300, 200) is which color, how can I do so? Thanks.

Check this - http://stackoverflow.com/questions/448125/how-to-get-pixel-data-from-a-uiimage-cocoa-touch-or-cgimage-core-graphics — rishi, Nov 08 '12 at 06:35
you should try the technique matt describes here: http://stackoverflow.com/questions/1042830/retrieving-a-pixel-alpha-value-for-a-uiimage -- of course, using a color destination bitmap. the benefit is that you don't need to allocate and draw the whole image to access the value of one pixel. — justin, Nov 08 '12 at 06:42

score 4 · Accepted Answer · edited Nov 08 '12 at 07:52

Call this method form uitouch move..

-(void) getPixelColorAtLocation:(CGPoint)point
{
    unsigned char pixel[4] = {0};
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef context = CGBitmapContextCreate(pixel, 1, 1, 8, 4, colorSpace, kCGImageAlphaPremultipliedLast);

    CGContextTranslateCTM(context, -point.x, -point.y);

    [self.layer renderInContext:context];

    // NSLog(@"x- %f  y- %f",point.x,point.y);

    CGContextRelease(context);
    CGColorSpaceRelease(colorSpace);

    NSLog(@RGB Color code "%d  %d  %d",pixel[0],pixel[1],pixel[2]);
}

You can get color code of touch point in RGB colr combination. try it

How can I get the specify point's color in the UIImage?

1 Answers1