ofImage get individual pixels

feature requests
#1

ofImage has getPixels() which will return everything, but I wanted to just get one pixel, without creating a new temporary pixels list to copy into for then getting that one pixel.

What do you think about adding this?

  
  
unsigned char ofImage::getPixelNum(int num){  
	if (IMG->isValid()){  
		return (unsigned char)IMG->pixels[num];  
	} else {  
		return NULL;  
	}  
}

The trouble is, with colour and alpha images, there are more values per pixel, but thats down to the coder to pull in the right pixel values.