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Book Review: The Art of Raw Conversion, reviewed by Nick Latito
Wednesday, September 20 2006 @ 05:24 PM EDT

Nick Latito (chiark on Groklaw -- he said I could tell you that) volunteered a while ago to review for us No Starch Press's "The Art of Raw Conversion," and here is his review. The book is more formally titled "The Art of Raw Conversion: How to Produce Art-Quality Photos with Adobe Photoshop and Leading Raw Converters", by Uwe Steinmueller and Jürgen Gulbins, ISBN 1-59327-067-4, published by No Starch Press and available from them and from the usual suspects, like Amazon and O'Reilly. You can view a sample chapter here.

It's about how to get high quality results with your digital camera, specifically how to work with the RAW files your digital camera generates to filter out imperfections, how to understand color management, adjust exposure, etc., or as the opening sentence puts it: "Our goal in this book is to demonstrate a reliable workflow that will help you achieve optimal image quality from your digital camera using the RAW file format." I gather they call them RAW files because they are describing the raw data the digital camera takes in when you take a picture.

I asked Nick to give me a sentence or two about him, and this is what he wrote:

Nick Latito confesses to being fascinated by digital imaging from the early days - remember Digiview on the Amiga in the 80s? Now using a Nikon D70, Photoshop CS2 and shooting RAW purely for pleasure, he's taken a look at "The Art of Raw Conversion" to see if it can improve his output and make his life easier.

As you will see, he really enjoyed the book and learned from it. His main complaint is that he'd have liked it to be longer. Note the postscript also.


Groklaw Book Review: The Art of Raw Conversion,

~ by Nick "chiark" Latito

First off, a slight caveat to Groklaw readers: this book, and therefore this review, really pays no attention to the Open Source marketplace. The only operating systems covered are Mac OS X and Windows, and the software covered is of a similar nature.

Introducing RAW

The audience of Groklaw is composed of geeks, law fans and parties with an interest in either or both topics. Some of you will have a better understanding of how digital cameras work than others -- some may have a much better understanding than I. If you already know what RAW is, skip on a few paragraphs, for I'm going to spend a while introducing what RAW actually is.

Digital cameras, in the vast majority, produce pretty decent JPEG images out of the box when you point them at something and press the shutter release button. What happens is that a shutter moves out of the way (in most cases), allowing the sensor to collect light at each pixel site (of which a 6 megapixel camera will have 6 million), which in turn produces a voltage at that pixel site. Things are complicated somewhat when you consider that each pixel site -- with the exception of Foveon sensor-equipped cameras -- only captures monochrome information, hence something else is needed to capture colour images: a colour filter is placed over each pixel site. Three primary colours can make up colours in the additive light model employed by computers, so three colour filters are used. That doesn't lend itself nicely to a repeatable (tessellated) pattern, so one red, one blue and two greens are used to make a two by two square. For the reasons why, Google "Bayer filter".

Your battery-powered camera's processor, tuned to give a compromise of size and battery life against performance and functionality, has to take the raw voltages from the sensor, apply correction curves, interpolate the data into a colour image, sharpen the image and generally work hard to produce an image prior to compressing the whole lot using cosine transformations and all sorts of gubbins to make a JPEG compressed image.

Many cameras now give the option to save the unmolested data from the sensor, or raw data, in place of or as well as the JPEG image and a handful don't even offer anything other than raw images out of the camera. The disadvantages of this are the size of the data -- as it's largely uncompressed data, it takes more space -- and that you have more control over the image which adds another decisive step requiring work into your current processing workflow.

The advantages are many: when you push that button on your camera and capture JPEG, your camera makes decisions which throw away information or make alterations difficult. Digital processing introduces the concept of adjustable white balance, which is something that film photographers have to understand but don't have much control over, other than changing film stock or applying filters to correct colour casts: to change white balance on a RAW image, just dial in appropriate settings on your converter. Your image is not subject to JPEG artefacts. Your sensor probably captures more than 255 levels of intensity at each site, but that's what JPEG is limited to, being an 8 bit per primary colour format: RAW will capture more, normally either 12 bits (4096 possible values) or 16 bit (65536 possible value) at each site.

Each different camera manufacturer has its own format for RAW images which often changes from model to model, so a RAW converter has to understand each manufacturer and each model to provide the best range of possibilities to the photographer.

On to the book!

So, with the understanding of what RAW can do for you, how can you use it? This book makes no apology for referencing the most popular image processing solution in its subtitle, that being Adobe Photoshop CS2, and if you're looking for help and advice using Linux, the GIMP or DCRaw, you'll not even find mention in this book.

The book looks and feels like a classy affair: it's a full-colour production on quality paper, and it appears that great care has been taken with the layout and design. It's bang up-to-date, and the bibliophiliac in me really appreciates it. Throughout the book, a fresh design has been used which works well with the subject matter. Callouts are used in the place of footnotes, keeping the feel modern. Illustrations are clean, clear and -- as they should be -- illustrative! The first page is a superb work of art beautifully presented that really does inspire, and each chapter starts in the same way. The quality of the included photographic work is very good. Coming in at just over 200 pages (240 to be exact), my impression is that the ethos is quality, not quantity.

The book starts by providing a detailed background to digital imagery and the tools you'll need. Even though I considered that I knew how things worked in some detail, there were still revelations in 7 pages: I'd rather that you took that as a comment on how rich the information is rather than a comment on my knowledge.

Following on from the basics are fourteen pages introducing colour management, hammering home its importance in getting the results that you want. This is an appropriate treatment of a potentially massive topic. Part of me would have liked more detail in here, and more concrete examples of how to get it right, but going deeper would take a lot more words backed with a lot more examples.

The book then opens up into the main objective: how to get the best out of your raw images now that you have the necessary background. Emphasis is placed that you should develop your taste and work according to what you feel is right, not necessarily what automated tools tell you that you want. Examples throughout the book show what is possible, and I'll reiterate that they're great but occasionally a bit more commentary or example would have been nice. The corollary is of course that others would find such commentary obvious, but I always like to understand what options someone had at steps to produce their final work.

Workflow is covered, and again I would expect that even seasoned professionals will find something in here, even if it's just affirmation that they're doing the right thing at the right time. The point that exposing correctly in camera will give you an easier path to perfection is well made. There are some assumptions on background made, and being honest I would have liked a bit more explanation here of some of the very basics to ensure that everyone's understanding is common.

We then come to the particulars of each software package covered, which takes 100 pages of the book. The author's aim is to show you that there's no one tool that does everything perfectly, and in that it succeeds. The largest section herein covers Adobe Camera Raw, followed up by Pixmantec Rawshooter, Apple Aperture, then a conglomerate of other raw converters. Adobe LightRoom is then given a fair crack of the whip, and the author's enthusiasm creeps through here: I sense that there might have been a struggle to fill the allocated pages, as a half-page picture illustrating no more than shortcut keys is included.

This was interesting for me, but it won't realistically mean I rush out and buy something else resulting from it. As an amateur, I can't justify spending more on another tool just to fill a specific gap that I haven't found by myself.

A brief chapter covering some image perfection techniques is next and, being frank, I believe that people reading this book will probably already know the content here in much more detail than presented. I also get the sense that this might have been added to bulk out the book: a page is apparently devoted to showing three screen grabs detailing the effect of the healing brush.

Back to the potential audience, batch processing is briefly but well illuminated which largely wraps up the main content. Chapters cover off the DNG format, how to use metadata, quality conversion to black and white, and how to profile your camera, which is a fascinating if very involving process.

As mentioned, the book does ooze quality -- it's beautifully laid out and produced. The language used is clear and appropriate for the topic, and there's only a couple of phrases that hint that authors are not native English speakers. That fact never once gets in the way of the book's ability to communicate, enlighten and entertain.

I did learn a lot from the book and enjoyed reading it. It's written with an easy and enthusiastic style by people who are passionate about their art. There are some topics which appear out of place in such a book and my honest feedback is that I'd drop some of these sections and expand on the core, or even just include more of the authors' superb examples of work, perhaps showing more of what they feel as right and wrong and the decisions they made at the various stages in their workflow to produce the finished articles.

It really does highlight that there is an art to this rather than a repeatable formula that gives perfect results every time, but at the same it time equips you with the background understanding, approach and tools needed to get the best. I liked the book, but I would have liked to have seen more of some bits and less of others. With that in mind, I'd recommend it to keen amateurs who own a DSLR and attach a caveat to check the content to ensure you're not, for example, expecting a manual of how to use Camera Raw in CS2 but rather a discussion on techniques and approaches to help achieve your own style and vision. As such, it succeeds but I'm left with a feeling of wanting a little more.

Postscript -- A note on open source

Whilst there are very capable image processing solutions, such as the GIMP, and raw interpreters such as dcraw it seems to me that open source has yet to address the needs of the professional or even keen amateur photographer. Photoshop is one major functional area keeping me on closed source, meaning that my next purchase will be a Mac as I now have a way out of Windows. When Linux gets great colour management as part of the OS, it will help. Adobe cannot be deaf to the fact that they have people clamouring for Photoshop on Linux. It was the most wanted application in a recent poll! I'd love to see this improve in the very, very near future, and it appears that people are actively working to crack this particular nut.

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