Changing Image through pixel manipulation(iphone specific) - iphone

Question

Similar questions must have been asked many times but this one is a tad different.
I am manipulating pixels of a image loaded in ImageView control from the photo library using the pixel values read from another image (rocks.jpg) .
Below is the code for the same:--
CGContextRef ctx;
CGImageRef imageRef = [self.workingImage CGImage];
UIImage* image2 = [UIImage imageNamed:#"rocks.jpg"];
NSUInteger width = CGImageGetWidth(imageRef);
NSUInteger height = CGImageGetHeight(imageRef);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGColorSpaceRef colorSpace2 = CGColorSpaceCreateDeviceRGB();
CGColorSpaceRef colorSpace3 = CGColorSpaceCreateDeviceRGB();
CGImageRef cgimage2 = image2.CGImage;
NSUInteger width2 = CGImageGetWidth(cgimage2);
NSUInteger height2 = CGImageGetHeight(cgimage2);
struct pixel* pixels = (struct pixel*) calloc(1, width * height * sizeof(struct pixel));
struct pixel* pixels2 = (struct pixel*) calloc(1, width2 * height2 * sizeof(struct pixel));
NSUInteger bytesPerPixel = 4;
NSUInteger bytesPerRow = bytesPerPixel * width;
NSUInteger bitsPerComponent = 8;
NSUInteger bpr2 = bytesPerPixel * width2;
//size_t bpp2 = CGImageGetBitsPerPixel(cgimage2);
NSUInteger bpc2 = 8;
CGContextRef context = CGBitmapContextCreate(pixels, width, height,
bitsPerComponent, bytesPerRow, colorSpace,
kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), imageRef);
CGContextRef context2 = CGBitmapContextCreate(pixels2, width2, height2, bpc2, bpr2, colorSpace2,kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace2);
CGContextDrawImage(context2, CGRectMake(0, 0, width2, height2),cgimage2);
NSUInteger numberOfPixels = width*height;
while (numberOfPixels > 0)
{
if(pixels->g == 250)
{
pixels->r = pixels2->r;
pixels->g = pixels2->g;
pixels->b = pixels2->b;
pixels->a = pixels2->a;
// pixels->r = 0;
// pixels->g = 0;
// pixels->b = 0;
}
pixels++;
pixels2++;
numberOfPixels--;
}
ctx = CGBitmapContextCreate(pixels,
width,
height,
bitsPerComponent,
bytesPerRow,
colorSpace3,
kCGImageAlphaPremultipliedLast|kCGBitmapByteOrder32Big );
if (ctx == NULL)
{
NSLog(#"The context is null");
}
CGColorSpaceRelease(colorSpace3);
CGImageRef img2 = nil;
if (ctx != nil)
{
img2 = CGBitmapContextCreateImage (ctx);
}
//CGContextDrawImage(ctx, CGRectMake(0, 0, width, height), rawImage.CGImage );
UIImage* rawImage = [UIImage imageWithCGImage:img2];
CGContextRelease(context);
CGContextRelease(context2);
CGContextRelease(ctx);
//self.workingImage = rawImage;
//[self.imageView setImage:self.workingImage];
//[imageView setImage:rawImage];
imageView.image = rawImage;
if (pixels != NULL)
{
pixels = NULL;
free(pixels);
}
if (pixels2 != NULL)
{
pixels2 = NULL;
free(pixels2);
}
The problem is that though I can read the pixel values and also manipulate them but the end result is that the second image(rocks.jpg) gets loaded in the view instead of the manipulated image being loaded.
Can someone help me out on this.??
Thanks in advance.