A UIImage category to read a single pixel as a UIColor

UIView+getUIColor.h

//
//  UIView+getUIColor.h
//  PRL_iPad_Catalogue
//
//  Created by Nigel Barber on 30/03/2011.
//  Copyright 2011 Mindbrix. All rights reserved.
//

@interface UIImage (getUIColor)

- (UIColor *)getUIColor :(int)xx :(int)yy;
@end

UIView+getUIColor.m

//
//  UIView+getUIColor.m
//  PRL_iPad_Catalogue
//
//  Created by Nigel Barber on 30/03/2011.
//  Copyright 2011 Mindbrix. All rights reserved.
//

#import "UIView+getUIColor.h"


@implementation  UIImage (getUIColor)

- (UIColor *)getUIColor :(int)xx :(int)yy
{

    // First get the image into your data buffer
    CGImageRef imageRef = [self CGImage];
    NSUInteger width = CGImageGetWidth(imageRef);
    NSUInteger height = CGImageGetHeight(imageRef);
    CGColorSpaceRef colorSpace = CGImageGetColorSpace( imageRef );
    unsigned char *rawData = malloc(height * width * 4);
    NSUInteger bytesPerPixel = 4;
    NSUInteger bytesPerRow = bytesPerPixel * width;
    NSUInteger bitsPerComponent = 8;
    CGContextRef context = CGBitmapContextCreate(rawData, width, height,
												 bitsPerComponent, bytesPerRow, colorSpace,
												 kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
    CGColorSpaceRelease(colorSpace);
	
    CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
    CGContextRelease(context);
	
	int byteIndex = (bytesPerRow * yy) + xx * bytesPerPixel;
	
	CGFloat red   = (rawData[byteIndex]     * 1.0) / 255.0;
	CGFloat green = (rawData[byteIndex + 1] * 1.0) / 255.0;
	CGFloat blue  = (rawData[byteIndex + 2] * 1.0) / 255.0;
	CGFloat alpha = (rawData[byteIndex + 3] * 1.0) / 255.0;
	
	free(rawData);
	
	return [UIColor colorWithRed:red green:green blue:blue alpha:alpha];
}



@end