Nov 30, 2008

RAW workflow, an introduction

Back in August I was thinking of doing an informal review of the various RAW workflow applications out there to determine which one would suit me best. I figured with three months off, I'd have plenty of time to do a writeup; I'm not sure how that never came to fruition. Hopefully I still remember enough to come up with something moderately useful in the next few installments. I definitely do not recall enough for a comprehensive review; my methods were neither stringent nor controlled.

Before jumping in, this is an introduction for beginners. What is RAW? Why should I use it? What's the difference between RAW workflow software and Photoshop?

The first digital camera I had, the Canon G1 in 2000, could save files to either RAW or JPEG format. At the time, I couldn't quite figure out the benefit of using RAW files. They were bigger, and they were a pain to "process" on the computer before I could post them online or do anything with them. This recent (and in my opinion, heavily flawed) comparison of the two options reflected my thinking back then: JPEG were easier to post online, RAW files were a hassle and used up all the space on my 128MB CF card. However, when I got my for dSLR, I spent more time playing with RAW, looked into RAW workflow software and eventually moved to shooting RAW exclusively.

The JPEG format was standardized in 1994, and is pretty much the standard for photos stored and displayed online. Pretty much every camera can save its images as a JPEG. JPEG uses a "lossy" compression format, meaning that it will drop detail information to make a smaller file. Most cameras have some quality settings for JPEG to balance the file size and detail level. At the highest quality level, detail is not a problem with JPEG. The primary issue with JPEG is that the range of possible colour values for each pixel is limited compared to RAW. Every pixel is stored as three values representing red, green and blue. In JPEG, each of these values is an 8-bit number, meaning it can range from 0-255.

Now unlike JPEG, there isn't a single RAW format. Rather the term refers to a camera specific format that contains all the "raw" data captured from the camera's sensor, before it's compressed into JPEG. As cameras improve, the RAW files contain more and more data that ends up being lost when compressed to JPEG. On my G1, the RAW file contained 8-bits for each colour component, no better than the JPEG. On modern dSLRs though, the RAW file contains up to 14-bits for each colour, a range of 0-16383. All this extra data is lost when compressing to JPEG. The camera picks a subset out of that range for each colour in order to get the proper white balance and drops the rest. Details in very bright or very dark areas may also be lost in the compression. Camera settings such as contrast, brightness, saturation and sharpness are also applied before saving to JPEG, and cannot be fully undone. Though not available on most point-and-shoot cameras, some form of RAW is available on some high end models and pretty much all dSLRs.

The larger RAW files gives much more flexibility to save not-quite perfect photos, especially when the white balance or exposure are off. These two changes in particular are practically impossible to do well after compression to JPEG. The extra data also lends itself to better results in general with other tweaks, reducing ugly "colour banding". With 4GB CF cards costing under $20, storage is no longer a significant problem; I'd much rather be able to recover an almost-perfect shot. Although modern displays can only show JPEG's 8-bits per component, technology is on the verge of improving this within the next few years. At some point in the future, all the extra data in RAW files would likely translate to richer colours and more detail in bright and dark areas than JPEGs would ever allow.

In addition to the file size, the other primary complaint about RAW files is the time required for processing. Back in 2000, the RAW conversion software that came with my G1 let me open a .CRW (Canon RAW) file, make some tweaks, and then save a JPEG version of the image. It might take a few minutes to go through this process, but even if it took me 3 minutes a photo, then going through say 300 photos from a wedding would still take 15 hours!

This is where the RAW workflow software comes in. Instead of following your average application's model of opening a file, editing and saving (much like Word or Photoshop), workflow software is specifically designed to expedite working photographers process of converting RAW files to JPEGs (or other publishing formats).
Usually this process goes through three main phases:
1) sorting photos, applying "tags" to make them easier to search later, and selecting the photos for publishing over a set of hundreds or thousands of photos taken over a shoot (known to photographers as "editing")
2) tweaking individual image settings of the selected good photos, and changing the picture to appear as desired (known as "postprocessing")
3) converting to a final JPEG (or other format) and printing, or publishing to DVD or the Web.

Workflow applications tend to combine all 3 steps into a single application. Photoshop on the other hand, is a general image processing app, aimed not only at photographers, but also for artists, video postprocessing and editing, game developers, web designers, graphic designers, publishers and even scientist, engineers and architects. Photoshop gives you amazing capabilities for step 2, but you'll need separate applications for steps 1 and 3. Workflow software on the other hand, gives the full package, but lacks the majority of Photoshops features in step 2. You'll be able to complete common photographer postprocessing tasks that apply to the entire image very quickly, with a UI and hotkeys designed specifically for efficiency: fixing white balance, exposure, contrast, saturation, "curves", cropping, sharpenning, noise reduction. However, any "special effects" will require a more advanced processing application. You probably won't be able to do stuff like cut the ex-girlfriend out of one image or insert grandma into another, changing the colours or license plate of a car, or removing wrinkles and adjust the unevenly large right eye of your aspiring models.

On the argument of RAW processing taking a long time, you'll realize that step 1 (and perhaps 3) are steps that are required if you take JPEGs anyways. Step 2 will take significant amounts of time if you process each image individually. However, if you just stick to the automatic settings (as you would have by shooting JPEG), and convert to JPEG, it takes about an extra 6 minutes for every 100 images, which is probably manageable for most photographers.

I took a look at three apps: Phase One's Capture One 4, Adobe's Lightroom 2, and Bibble Lab's Bibble 4.10. There's a number of other contenders. Camera manufacturers each have their own RAW conversion software, which I haven't looked at. Apple has Aperture, which is available on Mac only. It's a very serious contender, but since I use Windows, I haven't taken the time to review it. Hopefully I'll have individual discussions up soon.

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