Multi-RAW Processing
Creativity in the Photoshop Darkroom by Harold Davis, September 2009 (updated October 2010)
Intro | Multi-RAW Processing | Creating HDR Images by Hand [Part I] | Creating HDR Images by Hand [Part II] | Sharpening in LAB Color | Converting to Black and White | Using LAB Color Adjustments | Inverting Backgrounds with LAB | Intro to Compositing | HDR in Adobe Photoshop CS5 | Using Image Apply Image | Aging Photos Roundup | Making Colors Pop in Photoshop
My first and biggest “aha” revelation about digital photography took place the day I discovered multi-RAW processing—processing a single RAW photo file more than once. For me, the ability to process a RAW file multiple times—taking the best of each processing job for the final image—is the most important advantage that digital photography has over film photography.
If you don’t multi-RAW process, you can take photos with immediacy—but you are losing out on a great part of the richness of digital photography.
Let me back up a second to explain what I’m talking about. If you have a DSLR, it can probably be set to save your photos as RAW files, as JPEGs, or as both. RAW files have different file extensions (for example, NEF for Nikon and CR2 or CRW for Canon)—what they have in common is that these files store all the information from the time of exposure.
Essentially, a RAW file is a potentiality rather than a final rendition. Ansel Adams said of his work that a negative was a score, and the print the performance. In much the same way, a RAW file is the score, and what you do with it in the digital darkroom is the performance.
Embedded within the potentiality of the RAW file is a vast exposure range—as much as +4 to -4 f-stops in either direction from the exposure you made. If you do the math, since each f-stop has twice the exposure value of the previous f-stop, this represents a 2^8 or 256 times exposure latitude. So you can use RAW conversion to salvage poorly exposed photos—but more importantly, you can process the different parts of the photo to expose properly for each different part. Multi-RAW processing means that you are not stuck with one overall average exposure, which may be good in some parts and bad in others.
You can also use multi-RAW processing to selectively change white balance, saturation, and so on.
Got you interested? The best news is that multi-RAW processing is really a snap once you get the hang of it. Let me show you how it works using an actual example.
Sample File
I’ve provided a low resolution version of the red car reflections (red-car-reflections.tif) in TIFF format for you to experiment with and follow the example in this article. I chose to provide this file in TIFF format because I needed to lower the size and resolution of the file (I’m not about to let high resolution versions of my RAW negatives out into the world on their own!).
This TIFF file has the same settings and characteristics as the RAW file of the image, and you can use to it to try multi-processing and to follow along with the example in this article.
Note: In order to make sure that the TIFF file will open in ACR, check the “Automatically open all supported TIFFs” option in ACR preferences as shown below.
Photographing the Red Car
I recently spent some time photographing at a classic car show. The cars were polished up to the nines; what interested me most were the reflections in polished chrome, including the red car I’ll use as an example.
Unfortunately, I had an exposure problem, as you can see in the JPEG version of the photo shown in Figure 1. A single RAW conversion in ACR with default settings provides essentially the same results.
If I exposed for the sky (as in Figure 1), the reflections in the grill was definitely too dark. Had I reversed this and exposed for the dark grill area, the sky would have looked washed out. If you have this kind of exposure problem, you should be using multi-RAW processing.
Figure 1: Default version of the Red Car Reflections.
Organizing Your Files
Before you can process your files in the Photoshop Darkroom, you need to organize them on your computer. Programs like Adobe Lightroom can help you do this.
My own workflow starts with using a memory card reader to copy the RAW files from my camera to my computer. I store the files hierarchically in a chronology based on the date shot.
Once I have the RAW files on my computer, I can inspect them using Adobe Bridge, as shown in Figure 2.
Figure 2: The RAW file in Adobe Bridge.
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, September 17, 2009; 04:00 P.M. 
