Notice anything different? All three primary colors have changed position, with Green and Blue being practically off the chart. The size of the triangle is significantly larger. What this means is that the Pro Photo color space envelope is capable of reproducing a significantly larger array of colors than either sRGB or Adobe RGB and even colors that are outside the range of visual perception.  


The trick here is to understand the concept of working from the top down when it comes to resolution and color accuracy. Always develop your images in your editing software using a color space that will contain every possible color. For this I recommend working in the Pro Photo color space. Once you convert an image to a smaller color space, you are converting the color information to a smaller range of colors. Once those colors are converted, they can't be recovered. You can indeed switch the images color space back, but the colors won't be the same as the original, because they were converted to fit the previous color space. Converting back and forth can actually cause problems with how the color is reproduced. So, start large and stay large.


Never destroy the original and always make copies of the original that are designed for the media you intend to display the image, be it monitor, internet, or in print.


You may now find yourself asking, "why can't I set my camera to Pro Photo color space?"


The answer is simple.


What you set in your camera doesn't matter unless you're shooting JPG images. The color space isn't controlled by your camera, unless you convert an image in-camera to JPG. The camera writes the JPG image into a color space which is used when you open the image for editing on your computer. This is referred to as the "Embedded Profile. " If you're working with JPG files out of the camera, you are working with the the lowest quality common image file format. 8 bit files with a RGB color space.


JPG files are great for the internet, and most internet photographs will be best displayed using the sRGB color space.


RAW files though, can contain a wider range of color than sRGB. The Adobe RGB color space will cover most of the color any current DSLR can create and just about any color that can be printed on any current InkJet printer. In addition, you should be thinking about the future? Given the pace that technology changes, it isn't unreasonable to believe that 10 years from now, we'll have a better ability to display and reproduce a wider range of color. For this reason, I believe it is imperative that you shoot your photographs in RAW mode and insure that you develop your RAW images in the Pro Photo color space.


If you're shooting RAW format files, the actual range of colors isn't effected by your camera setting. You're passing pure raw image data from the sensor to the file and on to your editing software. By forcing your editing software to work in the Pro Photo color space, you'll be working with the largest range of possible colors. In truth, you probably won't even be able to see the full range of color because most computer monitors can't show them. Not even my very expensive Apple 30" Cinema display. Don't believe me, here is the color profile for my monitor.

So What Is All This Gamut Stuff Anyway?

Understanding Color Gamuts

By: Gary Gray


I'd like to introduce you to the basic concepts behind color management of your photography. This isn't a "Master" class on the finer points of color reproduction, but more of an introduction for those of you who are just trying to learn something new and something relevant to your photography. If you've already studied this aspect of digital imaging, you may just want to skip it.


Have you ever gone into your camera's configuration and set the color space? You'll probably have a couple of choices if you do. One will be sRGB and another called AdobeRGB. Most digital SLR's come with a default setting of sRGB. Very few digital cameras can produce a range of color that exceeds the AdobeRGB color space.


To complicate matters, we have color spaces in Photoshop and Lightroom and even other photo editing software. And if you want to get really complicated, you can look at your monitor and your printer calibrations. You'll end up scratching your head, but if you don't get a grip on your color, you'll never get your images to really look nice when you convert them or print them and even display them on a computer monitor.


Not all color spaces are created equal. To decide which color space to use, you need to understand how you intend to use your photographs.


Personally, I intend to make prints. When I make those prints, I want them to contain all the range of color they can obtain without losing something to a conversion. This is why I do all my editing in Lightroom & Photoshop using the Pro Photo Color Space. I'll show you why using a few color space graphs. These are screen captures of actual graphs from loaded profiles in my Mac Pro using the Colorsync utility. What I'll be showing you are 2D renditions of what is actually a 3D space, but it illustrates the differences between the different profiles quite nicely. The entire horseshoe area in color is the theoretical limit of human vision. The area defined by the "x" marks and lines (triangular area) is the gamut, or range of color that can be reproduced by any particular color profile or device.


We'll start with the most basic and that is the sRGB color profile. This is the color space used by most common computer monitors and is well within the range of most modern digital SLR's
Notice the three "x" marks on the graph. These represent the range of each primary color, Red, Green & Blue. The "x" marks show you the maximum value of that particular color that can be reproduced using this profile. The triangular area is the usable color space of the sRGB color profile. Now, lets take a look at Adobe RGB..
Now, compare the size of the triangular area to that of the sRGB color space. Notice that the triangle is a bit larger, most notably in the Green and Blue areas. What this means is that the Adobe RGB color space contains more colors.   Next, we'll take a look at the Pro Photo color space.    

Notice the "x" marks and the overall size of the triangle? My monitor can display a range of color that is close the the Adobe RGB color space. There are a few brands of monitor out there which have a wider gamut, and the costs for those monitors is exceptionally high. Your typical home computer LCD display will have a smaller gamut of viewable color then the Apple Cinema displays. You get what you pay for.


So, if your monitor can't display a color gamut larger than the Adobe RGB color space, why bother using anything other than the Adobe RGB color space for your photographs?


It comes back to "what are you doing with your images?"


If you're printing your images, you'll want to keep the color as close to the original color as possible. Adobe Photoshop will allow you to "soft proof" your image files to any color space. Soft proofing is where the software takes the full range of colors and compares it to the color space you intend to use and it gives you a visual warning of areas where the color is "out of gamut" or can't be reproduced. This allows you to check color accuracy for print images than can't been seen on your monitor. It gives you a way of seeing where your boundaries are for the gamut of your particular printer and allows you to tweak your image's color, keeping it closer to your visual intentions.


What about those "out of gamut" colors? How do they affect what I see on my print?


Since inkjet printers use a CMYK color space, any color that is out of gamut when it is sent to your printer has to be converted to a color that is within the gamut of your printer to stay within a CMYK color space. This is known as "Rendering Intent."


If you are working with Adobe Lightroom, you'll have two basic choices when creating your print. These are the two most common used in digital photography.




In perceptual rendering, the entire color gamut is compressed to meet the new color gamut. This more or less remaps everything to something else. The colors that are already well within the new range of colors are affected less, but for colors that are right on the outer limits or exceed the outer limits of the new color space, the change can be more severe. As a result of this type of conversion, images may have a greater degree of color inaccuracy, but the relationship between all colors in the image are well maintained so the overall image has a good balance between the colors contained in the image.


Relative Colorimetric


With this method of color space conversion, any color that is already within the new color space is left untouched. This maintains a perfect color match for most of the information. Any color that is outside of the new color range has to be converted and any out of gamut color is converted to the nearest color that is inside the new range. This can result in two colors that are supposed to be different actually looking the same.


My personal preference when making prints is to use Perceptual Intent when rendering color spaces from Pro Photo to CMYK.


So, to maintain the highest possible quality from your Digital SLR here's what you should consider doing.


Set your color space in the camera to Adobe RGB. The reason for this is to insure you are getting the largest gamut out of your in camera jpg files when you shoot JPG mode.


Set your camera file type to RAW. The reason for this is to insure the master image file has the widest range of color and the most detail possible to begin with. The only reason to shoot JPG mode is if you never intend to print your images and you never intend to edit your images and you are more concerned with saving file space than you are with the quality of your image.


You can always convert a RAW image to a JPG image. You can NOT convert a JPG image to a RAW image.


Set your working color profile in your photo editing software to Pro Photo. This insures that you never modify the color range of your RAW file and that in the future you'll have a greater range of color to work with from your RAW files.



Only convert the color space of your images when you are creating an image for output to the Internet, Monitor or for Print. Always optimize your color space selection for the type of medium you are using. Keep your original in the largest color space and bit depth possible and avoid multiple conversions, as each conversion will alter the image and thusly alter the color rendered.



Clear as mud?