Color Spaces

Digital cameras offer one of two color spaces for taking pictures with aRGB and sRGB.

The amount of different colors that can be recorded by the camera is related to the bit depth size of the image file being used, and bit depth is really not related to color space. We discuss the bit depth of color images on the link Color Bit Depth.

Color space is analogous to a painter that may use a selection of paints having a unique base to them, to create a different color palette for their paintings.

The term color space generally refers to a range of reproducible colors by an output device.

RGB refers to the color space of the additive color palette, or all the colors that can be represented by mixing Red, Green and Blue light that the human eye can see.

Realistically your camera's image sensor captures a bit smaller subset of the RGB color space gamut.

Your camera offers two common industry standards for color space. Adobe RGB is the larger of the two, and sRGB which was designed for internet use.

Adobe RGB (1998) or aRGB, is just one of many possible color palettes that exist today as a subset within RGB color space. There are many different color palettes because for every different type of technology, or even piece of equipment, there exist a unique and limited capacity to replicate color in the same way. Adobe RGB has become an excepted international standard for use with digital image sensors because this meets the needs of the professional publishing for a universally accepted broad color palette standard.

The sRGB color palette is smaller than Adobe RGB (1998) color palette and exist inside the boundaries of aRGB. sRGB was created in partnership between Hewlett Packard and Microsoft cooperation predating the aRGB color space. This color palette was designed to help standardize color for display by TV monitors of an earlier time, making color reproduction more predictable, and practical for transmitting over the internet. All the colors of the sRGB color space can be reproduced with a 24 bit image where each component of RGB is an 8-bit image with 256 different shades of brightness, which offered a potential of 16+ million colors. There were some professional TV and Flat panel monitors that were designed to display a broader color palette, but these were vary expensive and commonly used in a professional environment. Today, high quality RGB monitor displays are a bit more common.

The Adobe RGB color space being larger than sRGB, and has a greater capacity to replicate more accurate Blue, Cyan and green colors.

When you select Adobe RGB or sRGB in your camera to save your images in, you have selected industry standards for how colors should be interpreted by your target medium, so that those colors can be displayed with some degree of predicability.

When you are ready and happy with your image on your camera's LCD screen or computer monitor, and your are ready to print, your printer has the limitation of not being able to produce all those colors the way you see them on the monitor. Each printer, monitor and scanner has it's own limits of replicating color accurately within the large color space of RGB, so these limits of color range on the output device can be considered the color space of the device.

Color space designations is like instructions for what those colors are to be displayed as. The display or output device, might have a set of endemic instructions (ICC profile), that tells it how map those colors for it's own reproduction methods and technology.

Adobe RGB does not look radically different than sRGB. In fact if you switch back and forth between the two displays you may not see any change at all. Part of this reason is likely to be connected to the limits of your camera's LCD display device. The full RGB color space or even Adobe RGB color space can not be represented on that device, so switching the color space back and forth will present no visible change. So you first must have a monitor that can display some of these subtle differences.

If you intend to use the RGB colorspace to work within, you need to accept a more rigid color management work flow to care for those subtle differences. You will save your RAW file from the camera in the RGB color space. Your color monitor needs to one that can display all the colors of that color space, and it should be configured to display color correctly in your work environment. Generally people will use a third party color calibration system for assisting the color display of their monitor, that works to display colors while considering the limits of the target output device.

Your image processing software needs to be set to work in the RGB work space environment, one like Adobe RGB (1998), or ProPhoto RGB, and those images files need to be saved as RGB files. When it comes time to print to your professional printing device, you use the ICC profile for that target printer. All of this is done to help ensure the best possible care for the color with as few changes as possible being made to the image, as it is printed by a completely different technology based on inks and light reflectance rather than a technology who's base was using light and projection.

People who work in RGB color space must also remember to convert the image to sRGB if they display their images on the internet. The general idea behind this is that not all web browsers are capable of reading the image file's color space and then understand how to display the Adobe RGB image. And remember not all monitors display RGB anyway. So to convert your image to the sRGB color space is to give your image a chance to display correctly in everyones monitor or browser. An RGB image that is displayed as an sRGB image, will look muted and a bit dull compared to the sRGB image displayed as an sRGB image.

If your camera is set for the sRGB color space, your RAW file is still a wide gamut color space. You can still process your image taking advantage with all the features of your RAW file editor on your computer. And just like the pro photographers that are using RGB and practice careful handling of their image in a color controlled environment, you should apply good handling techniques of your color and work environment as well, even if you shoot sRGB.

You should be using the best color calibration for your monitor that you can manage, and handling your color in a proper workflow, in a controlled lighting environment that will assist you with making better color, contrast, and brightness adjustments to your images as you see them on your monitor.

Which color space you choose to use will be in part a choice of what your intended audience will be.

If you are sharing images over the internet, to be displayed on everyones TV or monitor, or for incorporating into different digital video formats, or sharing over the web (internet publishing), or for video presentations like power point, then your target color space is sRGB.

If you want your images printed for you at most consumer printing houses, then your color space is most likely sRGB as most of these printers are set up for running sRGB full time. sRGB is the file type that most of you here will be saving your final image in for display, whether your print it, or you are using it for digital display.

RGB is mostly a publishing industry color space, where the larger color space and gamut is needed to accommodate the inks used in the printing processes. Some professional photographers shoot RGB with the publishing industry standards in mind, for stock image sales. Many of the Stock agencies will not take your image at all unless it is still in the cameras RAW file structure. With this, agencies can work the file as they need to as a controlled output.

An image shot as sRGB and saved as a jpeg will not help you get back what was once recorded by the image sensor in the RAW file structure.

An image shot as RGB and saved to the cameras RAW file structure allows you to choose how you want to manage that image file in the color space of your choice, for all future uses.

sRGB images saved in jpeg format can print straight from the camera or flash card to a printing house like Costco or Walmart

Camera RAW files are not considered a recognize image file format and must be given a jpeg or tiff image format designation for printing at most printing houses. A camera RAW file can have a color space designation of RGB or sRGB.

A choice between using aRGB and sRGB gives you just as many colors for the image to work with, they are just different colors.

Color Spaces - RGB & sRGB

Color Spaces - settings of the monitor

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Your monitor's display settings makes a big difference in what choices you make when editing your pictures. If your monitor is not calibrated to a similar standard that other people's monitors are, then your pictures are going to look different on their monitors. And of course this is also true about printing, if you monitor is not close to correct display standards, then you will have a much harder time trying to print correct colors, exposure and gamma setting for your prints.

This is something you might care about if you share images over the internet, or are building webpages. sRGB color space with a gamma of 2.2 is a common setting for building webpages and sharing images over the internet. This is because at the time the internet was gaining it's popularity, more people were working with Windows based computer platforms, and Microsoft was building internet image standers for that purpose. This same sRGB standard has become a standard for poplar digital camera use, and thus has become a standard for consumer printing labs like that of Costco or Walmart, that can print direct from your camera or flash card if you shoot sRGB as a color space, and save your file in the Jpeg format. The point here is if you shoot in sRGB color space and save your images in the jpeg format, then you can print at these print labs, and the images will look much like the image does from your camera monitor, assuming you have not made adjustments to the camera LCD display.

The Gamma adjustment of your monitor display is a non-linear brightness adjustment algorithm that is needed to make the natural lighting of your scene appear natural when viewed on your electronic monitor. We mentioned before that monitors build for Microsoft Windows computers (with Gamma setting 2.2) were designed to show colors primarily to match that of the TV's of the day, and the needs of the internet.

Macintosh Monitors (with Gamma setting 1.8) were primarily set up to better assist the Publishing Industry, and so needed to be able show broader color gamuts of the RGB color space.

I have an old Apple Cinema Display that came set up at Gamma 1.8. As I am building this website I have adjusted adjusted my Gamma to 2.2 to match that of monitors of people that will most likely be viewing the internet through. This is so my pictures have a better chance of looking normal to your eyes of those view the internet.

The following displays the differences between the two most popular Gamma Settings. This image set was edited in sRGB color space, with my monitor set for 2.2 Gamma display. Now the colors are purposefully more saturated for this image to give the feeling of a warm sunset color, so the colors are not intended to represent color accuracy of the moment, the look was an aesthetic choice.

	sRGB Gamma 2.2 The image was edited under this condition
	sRGB Gamma 1.8 what this image edited at 2.2 gamma will look like whe displayed on a monitor with set at 1.8 gamma
	RGB Gamma 2.2 RBG display of sRGB image appears with duller colors. This is only to show what can happen to an RGB image if you can not control your color space.

Right or Wrong or whichever view you prefer in the above example, the point here is that how your monitor is set will effect your editing choices. In fact, I can't draw much conclusion for you in part because I don't know how your monitor is set up as you are viewing this.

But if you set your monitor and color space to a standard that is designed to work best for a specific output, you have a better chance of predicability of the outcome of the results.

What you do need to understand though is any color spaces can produce good saturated well exposed images, it's when you take your image out of the common workspace from which the image was edited in, is when you start to get variances. When you transfer the image from one technology to another, like printing the image, you need the assistance of ICC printer profiles that are correct for the output device and compatible with your color work space standard, like RGB with a Gamma of 1.8, or sRGB with a Gamma of 2.2.

Gamma settings on your monitor that are lower than they should be will make the image look a little darker over all, while gamma settings that are higher will make the image look a bit over exposed, or lighter.

So even if you have a Mac monitor, your images will look darker on computer monitors designed for the Window based systems, and the inverse is also true for images created on monitors with gamma set to 2.5, like windows based machines, when viewed on Macs they will seem a little bright.

Most people don't own third party color correction systems for their monitors, but in general this is one of the better ways to make adjustments and manage display differences between different out put devices. On some windows based machines, this maybe your only real option adjusting gamma, that is, through a third party color management program.

With Mac you most certainly can make fine adjustments in gamma, as these tools are available under System Preferences/Displays/color/Calibrate. It is pretty easy.

For people with older Mac systems that want to publish on the web, and share images over the internet, and use low budget printing houses for their prints, you can do what I did and re-calibrate your monitor to a Gamma 2.2 like the newer Mac monitors which are set at that current 2.2 default. A Mac can perform this procedure because their graphics cards allow for this adjustment. For making these adjustments in a MAC, see: The System preferences pane/Displays/color/calibrate.

Color Spaces - Settings of the Printer

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You do have the options of shooting in RGB in the camera, but for predictable results, you need the assistance of a third party color managements system to help you out, your image editing software needs to be set to a work space of RGB by default. You should have the ICC profile for your printer loading into your image editing software so that the color management system can adjust your monitor display those colors that will print out as you are editing your image.

Most commercial printing houses will print enlargements in sRGB and some will offer RGB as an option. Call ahead and find out how they are set up.

I prefer a printing house that offers an ICC printer profile as an option to download for my editing software. Not all labs offer this. The ICC profile describes the specific color space for the printer for it's inks, and specific paper, and surface that you are to print on. This information can be used by your image processing software, to display color and light on the monitor to help editing choices for the look of your final product.