Auto Tone inconsistency

[Serggg]

An "Auto Tone" adjustment can be applied to an individual photo (Develop->Tone->Auto) as well as to a batch of photos (Library->Quick Develop->Tone Control->Auto)

As I can see those 2 ways of applying produce different results.

a) Individually:

b) In a batch:

Why are the values different?

I use Adobe Photoshop Lightroom Classic CC. 8.1 Release. Camera Raw 11.1. Build 1200465.

[JohanElzenga]

Auto Tone in Library is indeed slightly different from Auto Tone in Develop. AFAIK, the reason is that Auto Tone in the Library uses the Library previews as the base to calculate it, and Library previews are different (different color space) than Develop previews.

[GoldingD]

Auto tone in the Develop Module will base the tone on the most selected image. It will not auto tone each individual image separately.

You need to do this in the Library module, where it works properly (mostly)

As JohanEL54 stated, the Library Module previews are different from what the Develop Module uses. The previews that the auto tone are going to key of to modify the tone are by default available to lightroom before you go and click that auto tone button. In Develop, previews are created on the fly, and only the most selected image as the preview available at the time you clcik on the auto tone button.

[Ian Lyons]

davidg36166309  wrote

Auto tone in the Develop Module will base the tone on the most selected image. It will not auto tone each individual image separately.

I can assure you that above statement is incorrect. When multiple images are selected in Dev module filmstrip and Auto Sync is enabled then applying Auto will adjust each image independently of the others. The key being that 'Auto Sync' in Develop module is enabled. Note that is is only visible when multiple images are selected.

[GoldingD]

Actually, to clear this all up, read the following from an actual Pro:

https://blog.thomasfitzgeraldphotography.com/blog/2018/1/applying-lightrooms-auto-settings-to-multip...

[johnrellis · Accepted solution]

Why are the values different?

According to Adobe employee Simon Chen (Auto Tone of a batch of photos gives different results than if you do them one at a time | Photoshop...

This is what happens, when the Auto button is activated, it means Lr has loaded the full resolution negative. So the Auto is computed based on this full resolution negative.

When you apply Auto to a batch of photos, for performance reasons, Lightroom loads a lower resolution negatives cached in the camera raw cache (like Smart Previews) and computes Auto from that. Since the two input are different, the results could differ slightly.

Most of the time, the differences between batch and individual application of Auto are very small and hard for a human to notice, e.g Exposure of -0.31 versus -0.36. But sometimes the differences can be quite noticeable, as I observed in that same topic.

If you have examples where the differences are visually noticeable, please upload the masters to Dropbox or similar and post the sharing link in that bug report. Adobe appears to believe that the differences are very minor, so unless users post counter-examples, they'll continue  believing that.

[bob frost]

I apply a preset to batches in Library's Quick Develop that includes Auto (Latest LR Classic). But I don't see any difference between applying it to a batch of files that way, and applying it individually in Develop.  Thinking about this, I suspect this is because I don't use the ACR cache in LR. Yes, I have one set, but I have also set it to Read Only and it is empty (deliberately). I have a pretty fast computer and don't think using the ACR cache produces any noticeable speed-up for me, so I prefer to remove that unnecessary task from LR (it already has far too much to do IMO).

So I presume that applying my preset with Auto in Library (with Quick Develop) makes LR render a full preview for each file as it does not have a half-baked one in the ACR cache. Am I right in my thinking or have I missed something?

Bob Frost

[DdeGannes]

Lightroom uses the lightroom generated previews while it is working in the Library module, while working in the develop module lihhtroom will utilize the ACR cache when working with raw files. The develop module renders from the original file, or from smart previews if previously built and the original files are not available. Develop module does not utilize the preview files. ACR cache files assist while working with raw files in the develop module.

[JohanElzenga]

DdeGannes  wrote

Lightroom uses the lightroom generated previews while it is working in the Library module, while working in the develop module lihhtroom will utilize the ACR cache when working with raw files. The develop module renders from the original file, or from smart previews if previously built and the original files are not available. Develop module does not utilize the preview files. ACR cache files assist while working with raw files in the develop module.

I don't think that has anything to do with it. If I understand Eric correctly, then Lightroom uses a full size cached preview from the ACR cache when it calculates Auto Tone in the Develop module. But when Auto Tone is applied in batch through the Quick Develop block in the Library module, then it uses a smaller image from the ACR cache (for the sake of speeding up the batch process). If there is no ACR cache, then the question is what it will use instead.