Lightroom 3, Adobe Camera Raw and Photoshop CS4

Posted on April 29, 2010 by Bahi Para

Categories: Blog

Some good news and updates recently for users of Lightroom and Photoshop CS4. Along with the good news is continued confusion in various online forums about Adobe Camera Raw and its relationship with Lightroom so here’s an attempt to explain some of what the two have in common.

What is Adobe Camera Raw?

Adobe Camera Raw (ACR) is a software plugin used by Photoshop to decode (or “demosaic”) raw files. A version is supplied with every new copy of Photoshop (and Photoshop Elements) and the plugin is regularly updated as new cameras are released because new cameras mean new types of files for the ACR plugin to understand. Any new major release of ACR (like ACR 6.0, 7.0, etc.) is usually available only for the latest versions of Photoshop and Photoshop Elements. The current version for Adobe Photoshop CS4 is ACR 5.7, released last week and available from Adobe as a free download. It works with Photoshop CS4 and Photoshop Elements 8.

Links to the (free) Adobe Camera Raw 5.7 downloads:

Does Lightroom use Adobe Camera Raw?

No, not directly. Lightroom’s decoding (or demosaicing) of raw files doesn’t rely on the ACR plugin itself so installing a new version of ACR won’t change Lightroom’s rendering or allow it to read new types of raw files. However, Lightroom and ACR share functionality and code—it’s just that Lightroom’s implementation is contained within the application itself. A new release of the ACR plugin for Photoshop usually means a corresponding release of Lightroom. The two are independent but usually updated together.

Adobe Camera Raw 5.7 and why it’s important for Lightroom 3 beta 2 users

ACR 5.7, like Lightroom 2.7, offered support for raw files from newly released cameras but that’s not the reason for this article. Version 5.7 also included a nice surprise for users of Lightroom 3 beta 2. It turned out to include the code to allow it to decode raw files using the new raw decoding engine contained in the Lightroom 3 betas—specifically, Lightroom 3 beta 2. This code is what gives Lightroom 3 its much improved colour noise reduction (see previous articles here and here) and finer detail. Till now, if you were working in a Lightroom 3 beta and chose “Edit in Photoshop” (command-E on the Mac, ctrl-E on Windows), you’d see an error message in Photoshop CS4 (if you were using LR3 beta 2) or just wonky results (in LR3 beta 1). When you install ACR 5.7, that problem is gone, allowing you to work on a raw image in Lightroom 3 beta 2, then open the raw file (including your Lightroom edits) in Photoshop CS4 and continue to do pixel-level work. Very nice.

A few weeks back, we wrote about the new and old process versions for Lightroom 3; what ACR 5.7 offers is really a way for Photoshop to work on raw images that you edited in Lightroom using the 2010 process. It doesn’t allow you access to the new noise-reduction controls directly from Photoshop but it does appear to respect the settings that you used within Lightroom 3 beta 2.

Sidenote: when you work on a raw image in Lightroom and choose “Edit in Photoshop”, Lightroom doesn’t immediately create a TIFF and send it across to Photoshop—the ACR plugin within Photoshop reads the original raw file and the list of changes you’ve made in Lightroom and applies those changes itself. The TIFF gets created only when you save the file in Photoshop. Now that version 5.7 contains a raw decoding engine that’s compatible with Lightroom 3’s, this process works again for users of CS4 and Lightroom 3.

What all this seems to suggest is that there will be a version of ACR for Photoshop CS4 that will remain compatible with the final release of Lightroom 3, meaning that you don’t have to update to Photoshop CS5 immediately to keep tight integration between Lightroom and Photoshop. If that’s true, it’s a very welcome gesture.

The obligatory gasp about Photoshop CS5’s content-aware fill

Photoshop CS5 looks like a very strong release for a certain type of photographer. If you haven’t already seen the content-aware fill demonstration, you’ve been missing out so take five minutes to watch it now. It’ll make your jaw drop.