Digital Light & Color

After some comments elsewhere on 16 bit masking, I decided to run a quick test to see if there is a noticeable difference between 8 bit and 16 bit masks. Not sure if this comparison is valid or not.

I took an image with some deep blacks (don't know if that makes any difference) and converted to 16 black and white and 8 bit black and white. I then did a Composite on the two, with Absolute Difference. Initially, could see no visible difference between the two. However, when I did a Levels and Colour, Full Dynamic Range, the result was a grainy, sand-like image (actually would make a good mask to introduce graininess to an image) with some anomalies in the darkest black areas. I did the same thing on a 48 bit black to white gradient image and, although much less obvious, the result only showed a speckled "grain" difference. I was sort of expecting a banding, in the gradient image especially, but not even close to that.

So, what does this graininess actually represent, and how does a 16 bit versus 8 bit mask impact the final outcome of an image?

Marv

I would expect the difference to be more or less random noise, assuming you start with a 48-bit color image and then convert it to 16-bit and 8-bit black and white and then look at the difference.

Since both B&W image are derived from the same color image, the differences between them should be less than about 1/256 or about 0.4% at most which is why you need to amplify the difference to see it.

Thanks for the explanation. Sort of makes me wonder why some are so adamant on 16 bit masks.

Marv