Absolutely nothing – unless you happen to be a photographer trying to scrape every last ounce of quality out of your digital pictures.
Perhaps you’ve heard photographers talking about RAW, so what is it? Let’s begin with the familiar JPEG format most digital cameras produce. JPEGs do not contain all the information that registered on the camera’s sensor when you pressed the shutter release. When you pressed it the computer inside your camera took the data from the sensor, applied white balance, sharpening, saturation, and several other variables to that image. Then it applied compression using the JPEC codec which basically throws away data it considers to be superfluous to the image, which is why JPEG is described as a “lossy codec.”
RAW is sometimes described as a digital negative but that’s not an entirely accurate description. RAW images are, as their name suggests, all the unprocessed data your camera’s sensor collected when you pressed the shutter without any processing carried out by the software inside your camera. Instead of allowing your camera to process that data without much interaction from the photographer, RAW files are processed back at your computer with lots of interaction with the photographer. RAW files aren’t really images until they have been processed or interpreted in some way by some other software. When you see the thumbnail of a RAW image on your MAC you are actually seeing one possible interpretation of the image data but there are countless other interpretations.
So here is the attraction; your camera pretends to be smart but really it is smart at math and it cannot really evaluate your specific subject with a photographer’s eye. When it captures image data from the sensor it processes the image to get the math right and it then throws away data it considers unimportant. Math is important to calculating exposure but it is not the sole concern. The correct exposure for a black cat in a coal cellar is very different from the exposure for a white cat in a snow storm but your camera tries to expose them both similarly (usually as 18% gray if you’re interested). When you shoot in RAW you get a second bite at the cherry as you are able to apply different settings to the RAW data as it is converted to an image in your computer, to compensate for problems you experienced out in the field.
RAW is not a real picture format as such; it is all the raw data the sensor collected. Before you can see the picture the RAW file first has to be processed. Your computer may do this on the fly or it may extract the compressed image within the RAW file to show you a preview of what the image might look like, but it is only a preview. When you want to work on a RAW file you must first process it. This is power of RAW. Instead of your camera guessing about how to process an exposure the photographer gets to decide how to interpret and process the image data and, as no data has been thrown away, the photographer gets something of a second chance to correct exposure mistakes.
In real world terms this means that if you under-expose a shot by more than a stop it will be hard to rescue that shot as a JPEG, but as a RAW file you will be able to create an image almost as if you got the exposure correct in the first place. This is especially useful in any less-than-ideal lighting situation such as using available light indoors, anything dark, anything with very high contrast but just about any shot can benefit from the flexibility RAW provides. These days I use RAW for all my shots unless speed is an issue. RAW files are much bigger than compressed JPEGs; they take up more space on your storage card and they take longer to write to it and when you’re taking action shots in burst/continuous mode, this bottle neck can be a limiting factor.
Perhaps you are getting the feeling that RAW image processing is not a simple subject. It can be tricky to get used to but it is worth pursuing if you want to make the best possible images from your camera. If your camera is not capable of storing RAW data (most digicams are not) or if you’re already perfectly happy with every image that your camera produces then spending time learning about RAW images is probably not worth your effort. If, however, you have a DSLR (digital single lens reflex) or a prosumer digicam that is capable of storing RAW images, and you recognize that your camera, smart though it seems to be, does not always set the exposure or white balance to the optimum values for the subject and conditions, then learning to use RAW can help you produce better pictures.
As RAW processing is a complex subject, you might need a book to supplement the information available on the web or that came with your image processing software of choice. There are many books on RAW available to you and here are three of the many that deal with the subject of RAW, listed in their Amazon sales rank.
Real World Camera Raw with Adobe Photoshop CS2
By Bruce Fraser
ISBN-10: 0-321-33409-4, 336 pages
Photoshop CS2 RAW
Using Adobe Camera Raw, Bridge, and Photoshop to Get the Most out of Your Digital Camera
By Mikkel Aaland
ISBN 10: 0-596-00851-1, 232 pages
The Art of RAW Conversion
How to Produce Art-Quality Photos with Adobe Photoshop CS2 and Leading RAW Converters
by Uwe Steinmueller and Jürgen Gulbins
No Starch Press
ISBN-10 1-59327-067-4, 240 pages
* * * * *
Real World Camera Raw with Adobe Photoshop CS2, by Bruce Fraser (Rank: #2,362)
As you can see from the Amazon sales rank, this book has sold well for Bruce Fraser. Flipping through it you can see why. The book is aimed directly at the photographer already using Photohop but not yet using RAW. If this is you, this book is a solid choice. Fraser does a good job of walking you through various processes and workflows, explaining the compromises of automation against creative control along the way. The processes he describes contain screenshots that let you know you are on the right path making it exceeding hard to get lost while following this book.
In the negative column, this book can get repetitive. I know that repetition can be a useful learning device but the same solutions and concepts keep reappearing in a slightly distracting way. This is not the only reason that this book is bigger and bulkier than it needs to be.
We seem to have arrived at a place where we expect our technical books to be big and heavy; do we think that the bulk adds gravitas to the subject or that we are getting better value buying our books by weight? The paper in this tome is thick, the fonts are large and the margins are wide. At the same time, the photographic reproductions are too small and their quality isn’t good enough to precisely see the point being illustrated. Some of the before and after pictures are so similar, studying them becomes like a spot-the-difference newspaper cartoon puzzle.
Still, this book is worth reading especially if you are a photographer new to RAW, but already comfortable with image processing concepts like histograms and color spaces. This book does not stray off topic much and so it does not go into elements of Photoshop outside the scope of RAW. If this audience description fits you, Fraser’s book may be an equally good fit.
Photoshop CS2 Raw: Using Adobe Camera Raw, Bridge, and Photoshop to Get the Most Out of Your Digital Camera, by Mikkel Aaland (Rank: #32,583)
Mikkel Aaland’s book aims at the same audience as Fraser’s book with much the same scope; the photographer already familiar with Photoshop but not yet utilizing the RAW format. Again, tools outside of Adobe Camera Raw get little mention, although I did appreciate that Aaland did not try to sell ACR as the miraculous solution to all photographic problems and that he does tell his readers what are the equivalent tools within Photoshop itself, and when they are more useful..
Again, reproduction of the photographs themselves, are not that great — am I expecting too much of a technical manual?
Again, the point being illustrated, before and after, is often hard to appreciate. The artistic standard of the images is also uninspiring; many seem little better than standard snapshots. They do illustrate the concepts adequately enough but they don’t make you want to rush to your computer to try them for yourself. The book also suffers from that modern technical book problem of a slightly distracting layout. A subject is introduced but is then followed by many screenshots and illustrations, sidebars and foot notes which can make it hard to remain focussed on the topic in hand as a reader.
If Fraser’s book suffered from repetition and information spread a little thinly, Aaland’s book is slightly the other side of the scale with an attempt to cover everything RAW is capable of in slightly too few pages. Again, if you are Aaland’s target audience (not a PS beginner and not already a RAW convert) you will learn a lot from this book. Subjects are easy to find, the recipes and concepts are not hard to follow and it will certainly give your initial foray into the world of RAW a good kick off.
Art of RAW Conversion: How to Produce Art-Quality Photos with Adobe Photoshop CS2 and Leading RAW Converters by Uwe Steinmueller (Rank: #160,209)
Uwe Steinmueller’s book addresses the RAW process in a slightly different way and for a slightly different audience. This book is the only one of the three that acknowledges that there are converters worth using other than Adobe’s Raw Convertor; this is both its strength and its downfall. It covers a lot of ground, showing you what tools are available and this could be useful if you haven’t already bought into a tool or workflow. A large part of the book is condensed, mini-manuals for each of the tools described. It is interesting to see this comparison but, at the same time, it is of limited day-to-day use and the information could date exceedingly quickly. The book does also describe specific RAW techniques but not in as much detail as either of the the two better selling volumes.
This book alone would not make the best reference for advanced RAW tasks, however, if you are looking for an overview to some of the tools available, their similarities and differences, strengths and weaknesses, Steinmueller’s book is worth considering. It might also be useful if you are looking to establish a RAW workflow. If you have already decided on which tool you want to use, and most photographers only use one, then a large percentage of the content will not be that useful to you.
None of these nooks are perfect. Unless an author knows you personally and writes for you specifically, you are not going to find the perfect instruction book on a creative/technical subject such as RAW processing. That makes any book on RAW something of a compromise. If you are new to Photoshop none of these books are for you. If you have been using the RAW format for some time already then you may pick up some information from any one of these books but you will already be familiar with much of their contents. If you are somewhere between the two you will learn from any of these books but don’t rely on one of them alone. Supplement them with some of the great web resources available out there or, if money isn’t an object, take a class specifically in the RAW workflow. These are available through professional orientated photography stores and specialized trainers. If this is not an option, try to find a photo-buddy who is familiar with RAW to walk you through their process. RAW can be confusing and daunting to understand and to learn but once it clicks you will find it difficult to go back to editing JPEGs.