Color spaces

One of the subjects I receive numerous questions about is which color space I use. Well, here is the answer: my color space of choice, as well as the one I use virtually for nearly all my photographs, is Chrome Space 100, Joseph Holmes.

The choice of color space is a subject on which there is a certain level of confusion. What I want to do in this essay is answer some of the most frequent questions I receive to shed light on this subject.

We will also be addressing this subject, hands-on and in person, with Uwe Steinmueller, Joseph Holmes and myself during the Fine Art Digital Photographer’s Summit this year in November. There is only so far you can go with an essay, and eventually attending a workshop such as the Summit is the best way to study, practice and return home with the skills you need to take your work to the next step. Everyone’s work is different, and at some point you have to have an expert look at your work and answer your questions personally, face to face, while looking at your prints.

This being said let me address some of the most common questions regarding color spaces.

Question 1:

If I am using Adobe RGB in the camera, what is the point of using a wider color space like Pro Photo RGB in Photoshop? I shoot everything in RAW. So does that mean that I am actually capturing the entire Pro Photo RGB color range in the camera in the RAW format even though the camera is set to Adobe RGB?

No. What you are capturing are the colors that your digital camera can record, independently of the color space (or color balance for that matter) you select in the camera. A RAW file is not an actual photograph until it has been converted in a RAW converter. Until then any color information is only tagged to the RAW file and later interpreted by the raw converter using either the choices made in the camera or the choices made in the raw converter. The tagged information is only a "recommendation" made by you, or by the camera, at the time you took the photograph.

When you convert your photographs you are free to chose any color space and color balance you like. Clearly, choosing a wide color space is to your benefit, which is why some photographers use ProPhoto RGB and why I use Chrome Space 100. If you do not indicate a color space or color balance during raw conversion then the raw converter will either use the choices that were tagged onto the raw file in the camera, or use the default choices set in the RAW converter.

A color capture device, i.e. a camera or scanner, does not capture color in any given color space nor are the colors captured by this device designed to fit a specific color space. The goal of a color capture device is to capture as many of the original colors as possible. It is then the responsibility of the user to save the image in a color space large enough to store all the colors captured by the camera or the scanner.

Think of the color gamut in an image capture as a collection of items you are bringing back with you from a trip. Once home you need to store these items somewhere. You choose a storage space. Hopefully this space is large enough for you to put everything in there without any problem. However if the space is too small to store all your items you will have to throw some of them away. It is the same with image captures and color spaces. Unless you use a color space able to store all the colors in your original capture, some of these colors will have to be thrown away.

To me the real question is why Canon (and other manufacturers) does not offer the choice of a wide color space in their cameras since Adobe RGB is not able to represent all the colors that the 1DsMk2 is able to record.

A graph showing the respective size of the ProPhoto RBG (wire frame), 1DsMk2, and Adobe RGB (on top) color spaces. The 1DsMk2 space fits nicely in the ProPhoto RGB space. The Adobe RGB space on the other hand only covers part of the 1DsMk2 space meaning that some colors captured by the 1DsMk 2 will be lost if photographs are converted to Adobe RGB. This graph, and the others in this essay, was created in Chromix ColorThink.

Question 2

What is the advantage of using Chrome Space 100 Joseph Holmes instead of Adobe RGB or ProPhoto RGB?
I use Chrome Space 100 for several reasons. First, it is a wide color space, wider than Adobe RGB. Two, it is the same color space I use with scanned film, thereby simplifying my workflow. Three, this color space includes Chroma Variants, which allows me to increase or decrease saturation by changing the color space rather than by using Photoshop Color Saturation sliders. I find that using the sliders changes not only the saturation (chroma) but also the hue and the brightness of each color. These changes are subtle, and are more noticeable with some images. However, they are unwanted changes, and having a solution that cancels them out –namely using Chroma Variants instead of the sliders- is a singnificant improvement.

The regular Chrome Space 100 color space together with two Chroma Variants: +50 saturation (represented as a wire frame in the graph) and –50 saturation (represented as a solid color in the middle of the graph).

Chroma Variants is something that I have only found featured in this specific color space. I may be wrong, and there may be other uses of the same concept out there that I don’t know about. Chroma Variants are basically color spaces that are variations of the original Chrome Space 100 color space. Each variant is either more or less saturated than the original color space. The saturation changes are done in 6% increments. There are 36 Chroma Variants total. 18 are oversaturated variants and 18 are under saturated variants when compared to the original color space. The total saturation variation available through the 29 Chroma Variants goes from +99% to –99%. The –99% variant gives you a black and white photograph.

The list of Chroma Variants is located under Edit > Convert to Profile in Photoshop CS2

To change to a new Chroma Variant you use Photoshop “Assign Color Space” command and choose the Chroma Variant of your choice in the drop down menu. Clicking the preview button in the dialog box enables you to see the changes before clicking OK.

My workflow is to scan my films or convert my Raw files to the main Chrome Space 100 color space, then change to the Chroma variant of my choice in Photoshop using the Assign Profile command.
This color space is available for $100 (for all 29 variants) by emailing Joe Holmes at jh@josephholmes.com You can also read additional information and download a PDF file with detailed information about this color space at http://www.josephholmes.com/profiles.html

Note that a free color space called Ekstaspace PS 5 is available for download from this link. Although it will give you a good estimate of the nature of Holmes Color Space, this free color space is not comparable in quality to the one for sale. It also does not include Chroma variants.

A photograph converted from RAW to the standard Chrome Space 100 color space
(no Chroma Variants used)

The same photograph converted from the regular Chrome Space 100 to the -50 sat. Chroma Variant (top) and +50 sat. Chroma Variant (bottom). The difference is very noticeable and only due to color space changes. No other adjustments were made to the image. To get this effect without Chroma Variants you have to use the Saturation controls in Photoshop.

Question 3

In your article on the new 1dsMk2 Canon camera, you mentioned that you use Joseph Holmes' Chrome Space 100. I've tried his free Ektaspace PS 5 as well as the ProPhoto space recommended by Bruce Fraser. I've found the ProPhoto to be both more saturated and more luminous, so naturally, I'm wondering if it's worth the money to buy Joe's for-sale color space files.

A graph of the sRGB, Adobe RGB, Chrome Space 100 and Pro Photo RGB color spaces created with Chromix ColorThink. I used different renderings for each color space to show how they visually compare to each other. A visual representation such as this one is the best way to visualize the respective size of each color space.

As I just mentioned there is a significant difference between the free color space available on Joseph Holmes web site and the one for sale on the same site. I use the one that is for sale, not the free one. There is no doubt that the free space will not deliver the same quality results. As usual, you get what you pay for.

On the subject of ProPhoto vs. Chrome Space 100, I converted the same RAW file with Capture One into both color spaces and I could not see a difference when comparing the two resulting photographs in Photoshop. This may be due to how many colors my monitor can reproduce or to my choice of photograph. It is also possible that I will get different results with different photographs, especially with photographs that have a particularly large color gamut. However, my belief is that since both are wide gamut color spaces the differences are not very noticeable. The main difference between these two color spaces are the Chroma Variants that come with Chrome Space 100. The other difference is that ProPhoto RGB is a larger color space than Chrome Space 100. Logically, a larger color space is able to hold more colors and therefore should show a difference in color quality. However, as I said, I have not seen a difference so far. But, to be completely thorough, and not loose colors in my photographs, I now convert many of my RAW files to both color spaces. This is easy to do in Capture One since you can create several conversion setups, save them under different names in the Process Tool dialog box (on Mac OSX), and then elect to have the same photograph converted to any number of these different setups as you like, simply by selecting the ones you want to convert to. You only need to click the Process Image button once and the photograph will be converted into two different TIFF files automatically, one file for each color space in this instance.

Note that Chrome Space 100 was designed for scanned Ektachrome transparencies and not for converting RAW files. There can therefore be minor differences when this color space is used to convert RAW files. However, in my experience it works very well with both scanned film and Raw files. Although it is unlikely, your experience may prove otherwise and if so make sure to let me or let Joseph know.

Question 4

How do you compare color spaces from a technical and objective standpoint?
By using Chromix ColorThink or, if you work on a Macintosh, by using ColorSync Utility. You will have to buy Chromix ColorThink while ColorSync Utility is part of Apple OSX.

The ColorThink logo says it all in regards to the purpose of this software

Chromix is a more complete software package than ColorSync Utility. However, both allow you to perform the same functions, which is comparing color spaces, looking at the technical data of your profiles and study how profiles & color spaces operate and interact. You can also rename profiles, inspect them, fix errors, make various changes etc. I personally use both tools mainly to study and compare profiles and color spaces. Doing so is educational and allows me to predict how colors will be modified and eventually how they will appear in print.

Do not hesitate to email me your questions or comments: alain@beautiful-landscape.com
Also make sure to visit my website at http://www.beautiful-landscape.com

This is one of the many techniques we will teach during the 2006 Summit. We will also work with you 1 on 1 and help you with your own images and with how to use this technique, and many others, in your own work. Click here to read a detailed description of the 2006 Digital Fine Art Summit. Joseph Holmes will join the Summit 2006 as a guest instructor means you can ask this world class printing expert directly.

About the Fourth Annual Photography & Fine Art Printing Summit

The 4th Photography & Fine Art Printing Summit will take place November 10th to 13th, 2006, in Page, Arizona. Seats are limited. In addition to studying color management and color spaces, we will also do field photography in stunning locations such as Antelope Canyon, Lake Powell and Horseshoe Bend, as well as study Raw conversion, Photoshop processing, image optimization, printing. We will also conduct print reviews of your work created during the Summit. Find out all the details of this unique learning and photographing opportunity on the 2006 Summit page.