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[jcafaro10]

Originally Posted by Delirium

I believe all Quartz color and alpha values are floats between 0.0 and 1.0, where 0.0 would be 0, and 1.0 would be your 255.

How does an image get turned into a data array specifically? I'm trying to figure out why I'm getting bad accesses on some images. I think it has to do with how I'm calculating the byteIndex but not sure. The problem occurs at some point during the for loop where the byteIndex is becomes the size of the rawData array which is obviously not good.

	CGImageRef image = [imageView.image CGImage];
	CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
	NSUInteger width = CGImageGetWidth(image);
	NSUInteger height = CGImageGetHeight(image);
	NSUInteger bytesPerPixel = 4;
	NSUInteger bytesPerRow = bytesPerPixel * width;
	NSUInteger bitsPerComponent = 8;
int size = height*width*bytesPerPixel;	
	unsigned char *rawData = malloc(size); 
	CGContextRef context = CGBitmapContextCreate(rawData,width,height,bitsPerComponent,bytesPerRow,colorSpace,kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
    CGColorSpaceRelease(colorSpace);
	CGContextDrawImage(context, CGRectMake(0,0,width,height),image);
	CGContextRelease(context);
	
	for(int x = 0; x < width; x++)
	{
		for(int y = 0; y < height; y++)
		{
			int byteIndex = (bytesPerRow * x) + y * bytesPerPixel; 	
			int red = rawData[byteIndex];
			int green = rawData[byteIndex+1];
			int blue = rawData[byteIndex+2];
		    int alpha = rawData[byteIndex+3];
			//printf("%d,%d: %d,%d,%d,%d\n",x,y,red,green,blue,alpha);
		}
	}