12 vs 14 bits? difference? 1000D

Started Jun 10, 2008 | Discussions thread
EricDP Regular Member • Posts: 456
Re: 12 vs 14 bits? difference? 1000D

thejaybird wrote:

the difference is the loss of highlight priority and probably less
headroom in the RAW file

Highlight priority may have come at the same time as 14bpc, but it isn't dependent on 14 bits. All 14 bits means is that you have more shades between any given colour. In areas where contrast is limited (often in shadows) you can stretch the curve without banding occurring. It may also be a benefit in low-contrast mid-toned photos (e.g. with fog, where then entire photo lives inside of one stop). You can stretch the curves out to their extremes and find a beautiful high contrast photo in there, and have no banding. If you had a jpg and tried that, it would look terrible.

Too many people compare the final image and try to see the difference, but you can't because your eyes don't see that may colours! More bits per channel is all about flexibility in post processing to recover images that might otherwise be throw away. If the image is perfect to start with, then the extra bits don't get you anything.

Here is a demonstration of (an extreme case of) the benefit of higher bit depth. In this case, it is 8 bit vs. 12 bit, and going up to 14 bit will yield even more improvement. Imagine the spectacular raw image of fog:

Now let's say you wanted more contast... if all you had was 8 bits per channel - i.e. you used jpg mode to take the picture - and you stretched the curve, you would end up with this:

But applying the exact same curve to a 12 bits per channel version of the image yields this:

The 12bpc still isn't perfect, but the colours are considerably smoother. Moving to 14bpc would improve this even more...

And that is all you get with more bits. More dynamic range is a completely different thing, also a good thing, but in no way related to more bits per channel.

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