Adjusting Exposure in ACR/Lightroom v. Photoshop

I'm sure this has been covered before but I'm not quite sure how to find it.

When I open up a RAW image file in ACR and adjust exposure using the exposure slider I get a lot of latitude up to EV +2.0 if not more - basically as long as I am not clipping the exposure adjustments act just as they would if I had shot at a greater exposure in camera. Little noise, sure, but basically all is good. Where things get ugly is if I forget to do this in ACR and wait until Photoshop proper (CS4 in my case).

When I create an exposure adjustment layer in PS and up it even a little bit, the results are horrible! I get banding, clipping, weird tone mapping - basically not a very useful tool in my book. Even up as little as EV +0.7 it's bad.

Why is this? Or is it something I'm doing wrong? I'm just wondering why I have so much more latitude in adjusting exposure using ACR v. Photoshop when on the surface I would think they'd do the same thing, same file depth etc.

In ACR are you working with Raw? It makes a difference -- let us know so we can give you some informed ideas!

In ACR file says X.CR2, below that Adobe RGB; 16 bit. I'm assuming that's a Raw file, correct? When it opens up in PS I have no idea what it's converting it to but I believe it's >12 bit since I always have to convert to 8 bit to save it as jpeg.

Here's an example. Same picture, shot in Raw, uploaded into ACR. The only difference between the two is adjusted exposure +1.1 in ACR, and the other one I adjusted exposure in PS as a layer adjustment set to +1.1. So by this I'm assuming that the settings are different (ie, +1.1 EV in ACR not the same as +1.1 EV in PS) and/or that it's always better to adjust exposure in ACR. I guess I was just surprised to see there was such a big difference.

IMAGE LINK: http://www.flickr.com …pan_hong_kong/7​049602235/

IMAGE LINK: http://www.flickr.com …pan_hong_kong/7​049602227/

Well, yes, Raw data is better for doing this type of thing, due to the nature of, well, the Raw data.

Once you open a file in Photoshop it has been converted/rendered to an RGB image. As the note at the bottom of the ACR preview says, ACR is converting to a 16 bit-per-channel image, which is the better options when doing "serious" work in Photoshop, but still it has been "rendered" -- it's no longer Raw, and there are limits to what you can do.

So yeah, it's good to maximize your work with Raw files in ACR!

Exposure in Adobe Camera Raw/Lightroom and Exposure in Photoshop serve two entirely different purposes. In Photoshop, the Exposure adjustment (direct or adjustment layer) is primarily for working with HDR images. In ACR/Lightroom the Exposure slider works in the way photographers think about adjusting exposure.

From Photoshop Help files: "The Exposure and HDR Toning adjustments are primarily designed for 32-bit HDR images, but you can also apply them to 16- and 8‑bit images to create HDR-like effects."

PixelMagic, are you talking about the Exposure Adjustment Layer? I would have never guessed that it was designed for HDR files...you don't know unless you know, right?

'Course it can be used for "regular" images, but with less latitude than you have with Raw files for sure!

One major difference between ACR and PSCS proper is that ACR starts to perform its various operations with linear data. Thus Exposure is a linear shift of all the data upward or downward, think of it as moving the entire histogram to the right or to the left. This is the same as what happens when you alter the EV in the camera, all the light is affected equally. One of the final operations it performs before sending the RGB image to PS is to apply a gamma tone curve, which expands the shadows and compresses the highlights. The TRC has also been modified from its basic gamma 2.2 shape by the various edits you did in ACR. The result is that the image in PS has already been skewed, twisted and distorted and editing it has become more difficult, requiring much more complex algorithms.

Hey thanks, that makes sense (not saying I understand everything you just said, but it makes sense . What I can clearly see is the non-linear adjustment in PS you talked about vs. linear in ACR. In PS, the surfer's skin tones and shirt (midtones and shadows) did not receive the same exposure adjustment as the white water (highlights), whereas everything was adjusted relatively equally using exposure slider in ACR and I can see further proof of that as I watch the histogram slide to the right while maintaining the same shape.

And I never realized Exposure adjustment in PS was intended for HDR or 32-bit images - so is it more linear when used there? Just curious

I rarely use Exposure adjustment in PS anyway (mostly just Curves or Levels), but it's good to know how it works and all the more important to make those adjustments in ACR or LR when you need to.

tonylong wrote in post #14218658
PixelMagic, are you talking about the Exposure Adjustment Layer? I would have never guessed that it was designed for HDR files...you don't know unless you know, right?

'Course it can be used for "regular" images, but with less latitude than you have with Raw files for sure!

Exposure works the same way when applied directly to the image via the Image > Adjustments menu or to an adjustment layer via the Layers palette. I remember learning the difference between the Exposure slider in ACR and Exposure in Photoshop in similar thread a few months ago. I checked several references and they all say the same thing although they are all sketchy on the details. Exposure in Photoshop basically allows you to manually tonemap an HDR image.

Here's the link to the offical Adobe explanation: http://help.adobe.com …c9d8124ebb76a73​-8000.html

And from the Photoshop CS5 Bible:
"The Exposure tool was designed to be used in HDR images with much greater tonal ranges, even though it does work with 8-bit and 16-bit images. A good rule to follow is to use the Contrast and Brightness tool when working with 8-bit images and the Exposure tool when working with HDR images. Then, if you can’t get the lighting correction you need with the Contrast and Brightness tool, you can use the Exposure tool to get a better result."