Adobe Development and Auto Tone Algorithms

I shoot raw, and develop in Lightroom. (Version 2; just haven’t upgraded quite yet but I suspect the questions are the same for the recently released version 3.) Sometimes the results are pretty good out of the box, but usually they require a lot of manual tweaking to make the light work. I suspect they may be designed more for wedding and portrait and landscape photography and the like and less for the wildlife and macro photography I like to do. There are two areas I have questions about, the initial settings and the auto adjustments.

Here’s a harvestman with Lightroom’s default settings:

Here’s the same harvestman with manual tone adjustments. Notice how much clearer it is, and a lot closer to its “true” colors in the field:

And here it is again with auto tone:

In general, autotone seems to have more trouble with darker settings than with brighter ones. It may also have trouble with a darker figure at the center compared to a brighter background (not uncommon when shooting tiny bugs.) though that’s not obvious in this picture.

The initial tone settings on all photos are:

Exposure: 0.00
Recovery 0:
Fill Light: 0
Blacks: 5
Brightness: +50
Contrast: +25

Recovery 0 and Fill Light 0 make sense. A properly exposed photo doesn’t need either of these, and how much of which will vary widely from one photo to the next. Buy why set Blacks to 5? That’s almost always too high for my photos.

Why is Brightness set to to 50 and exposure to 0? Why not set exposure to .5 and Brightness to 0 instead? Or why 50 and not 45 or 55? or 25 or 65? How were these numbers arrived at?

Why is Contrast +25 and not +20 or +30? Where did these values come from? Is it plausible that they’re all multiples of 5?

Second question: Auto Tone. Sometimes it works and sometimes it doesn’t. It almost never picks a reasonable recovery or fill light value if a photo needs that. How is it calculated? Has Adobe ever explained what’s happening here? The one thing I’ve been able to determine is that cropping doesn’t seem to affect the results. I.e. Lightroom makes its adjustments based on the entire photo rather than the cropped portion. It might do better if it would just look at the piece of the image I want to keep.

As I said, I use Lightroom, but I suspect the questions are the same for Photoshop and anything that uses Adobe Camera Raw. Can one play with the algorithm at all? I know how to make a preset that chooses fixed values, or that uses Auto Tone, but I’d like a little more control, something that can consider the nature of the photograph itself before choosing the adjustments. Is there any way to do that?

One Response to “Adobe Development and Auto Tone Algorithms”

  1. Dolan Halbrook Says:

    I recently upgraded to 3 and noticed that the Auto Tone seems to be a fair bit better. Still not quite “magic” but fairly usable, for a guide if nothing else. It now uses fill light (yay!). Ultimately I tend to do things by eye at the end of the day. It’s time consuming, but since the finished photo is quite subjective I think you’ll only get so far. I’d love to see the algorithm they use as would you, but I’m guessing it’s considered proprietary :)

    You should download the LR3 trial and do a comparison. If nothing else I think 3 is worth it for the vastly improved noise handling — it’s like getting an extra stop from all your lenses for $99.

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