Inappropriate Images display due to overlapping in CGContext - iphone

Question

I can't find the solution for this:
I have 2 image Views both with different image - image_1(Jeans of Person) and image_2(Shirt of person). Now when I change the RGB value individually for image_1's or image_2's each and every pixel, I get the perfect result. But whenever one of my frame from the two, slightly overlap with other after processing both of them, then the problem occurs. Please help. This is how I am processing the image.
-(UIImage *)ColorChangeProcessing :(int )redvalue greenValue:(int)greenvalue blueValue:(int)bluevalue imageUsed : (UIImage *)image
{
CGContextRef ctx;
CGImageRef imageRef = [image CGImage];
NSUInteger width = CGImageGetWidth(imageRef);
NSUInteger height = CGImageGetHeight(imageRef);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
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 * 0) + 0 * bytesPerPixel,RED = redvalue,GREEN=greenvalue,BLUE = bluevalue;
for (int ii = 0 ; ii < width * height ; ++ii)
{
if(rawData[byteIndex] != '/0' || rawData[byteIndex+1] != '/0' || rawData[byteIndex+2] != '/0'){
if ((((rawData[byteIndex])+RED)) > 255)
{
rawData[byteIndex] = (char)255;
}
else if((((rawData[byteIndex])+RED)) >0)
{
rawData[byteIndex] = (char) (((rawData[byteIndex] * 1.0) + RED));
}
else
{
rawData[byteIndex] = (char)0;
}
if ((((rawData[byteIndex+1])+GREEN)) > 255)
{
rawData[byteIndex+1] = (char)255;
}
else if((((rawData[byteIndex+1])+GREEN))>0)
{
rawData[byteIndex+1] = (char) (((rawData[byteIndex+1] * 1.0) + GREEN));
}
else
{
rawData[byteIndex+1] = (char)0;
}
if ((((rawData[byteIndex+2])+BLUE)) > 255)
{
rawData[byteIndex+2] = (char)255;
}
else if((((rawData[byteIndex+2])+BLUE))>0)
{
rawData[byteIndex+2] = (char) (((rawData[byteIndex+2] * 1.0) + BLUE));
}
else
{
rawData[byteIndex+2] = (char)0;
}
}
byteIndex += 4;
}
ctx = CGBitmapContextCreate(rawData,
CGImageGetWidth( imageRef ),
CGImageGetHeight( imageRef ),
8,
CGImageGetBytesPerRow( imageRef ),
CGImageGetColorSpace( imageRef ),
kCGImageAlphaPremultipliedLast );
CGImageRef NewimageRef = CGBitmapContextCreateImage (ctx);
UIImage* rawImage = [UIImage imageWithCGImage:NewimageRef];
CGContextRelease(ctx);
free(rawData);
CGImageRelease(NewimageRef);
return rawImage;
}
Now on Any button action you can set R,G,B & image values and get the processed image after that. Then just try to place those processed images frame so that some of the part of one image is covered by another. Means if you have jeans image just try to place the small portion near belt over shirt image.

Answer 1

Finally I came up with the solution that is I was missing to check the alpha value. So the transparent image part was the one which created problems. Thanks all.