Mid-December. Last blog of the year. Early darkness and grey, usually rainy days. Nothing to be glad about. Except that this year is coming to a close and Covid-19 vaccines have just been approved for both Canada and the US. This crap will soon be behind us. The only reason to rejoice. But you know what would be worse? Not adhering to public health measures, getting sick and dying a few weeks before you are scheduled to get a vaccine. That prospect should really make you determined to stick it out. And it would really really make your family angry if it happened. So don’t drop your guard now. Just a few more months. Hang in there.
And while you hang in, a little treatise on photography. There are many confusing concepts in photography. When I find one, I research it, then share it with you, hopefully making your photography life easier in the process. Today’s choice: colour, specifically colour profiles, colour gamut, the choices available and why one choice is better than another (or is it?). Read on to find out.Every creature or device that sees colour information does so within the bounds of a range perceptible to that creature or device. We know from science that there are wavelengths of light visible to us and wavelengths that are not. Hopefully you also know that light does travel in waves – well, waves and packets, but we won’t go there. For today’s exercise, let’s just say waves. We also know (hopefully) that our imaging devices suffer the same fate, and can either detect or display specific wavelengths of light and not others.
The challenge comes when we use devices that detect certain wavelengths, software that is capable of processing and storing data on a different range of wavelengths, and projection devices that interpret and emit yet different wavelengths. And more difficult yet is the act of having all of them communicate so that red is red is red. The often confusing advice I’ve read or received about how to have all of these interact is the subject of this piece.
Does any of the following advice sound familiar? Set your camera to Adobe RGB. When importing your photos, use Profoto RGB. When printing your photos, use Adobe RGB. And when sharing or posting your photos to social media, use sRGB. Seriously?
I’ve found a much more useful instruction, and it doesn’t take as long to repeat. It is this: don’t throw away colour information until you have to. In other words, work with as wide a colour space as possible for as long as possible, ensuring as much information as possible is retained, and scale that down only when you have to.
How to apply that in a practical sense, at the camera, on import and when exporting?
Almost all cameras can now shoot in RAW. From a colour perspective, this means that all of the colour information that the sensor can detect is recorded when shooting in RAW. So in keeping with our principle of retaining as much information as possible for as long as possible, everyone should always shoot in RAW.
Why then is there a setting for colour space in the camera? Simply because a RAW file is not an image. It is data. In order to see a preview image (if shooting mirrorless or with live view) or to review your images in-camera afterward, the camera has to be told how to interpret the data. As of this writing, the only two colour spaces used in-camera are Adobe RGB and sRGB.
Maybe this is a good spot to talk about what colour spaces are. They are really standards set by leading companies such as Adobe to identify the number and breadth of colours that can be handled by software or a device. Colour spaces define the relationship and separation between the colours and just how many shades of any one colour will be included.
The notion of even creating a colour standard first appeared in the 1970’s, when a standard to which all companies should aspire was set by the International Commission on Illumination (CIE). The way to illustrate a colour space was also created at that time. Generally, it involves what I call the “spatula” diagram, in which the CIE standard is plotted in three dimensions and the colour space offered by software or a device is overlaid on it. Strangely, the third dimension (which illustrates the visible shades of any particular colour) is often not represented in a standard diagram (as in the examples here) but can be found with a quick search, if of interest.
All photography-related colour spaces were invented when digital photography and digital printing first began to gain a foothold at the consumer level in the late 1990’s and early 2000’s. As you can anticipate, the colour capability of software and devices has expanded over time, meaning that older colour spaces are smaller and later colour spaces are larger. There are actually many different colour spaces, but typically only 3 are used by photographers, more in printing. And “gamut” is a word associated with colour spaces to identify the range of colours available in that space. “In-gamut” or “out-of-gamut” are terms that you may encounter as you work with these spaces.
First on the scene was sRGB, invented by HP and Microsoft in 1996. It stands for, wait for it, “standard red green and blue”, defining the range of colours capable of being produced by combining 8-bit red, green and blue primary colours. That means 256 different colours, which doesn’t sound like a lot, but works well in many situations. Being first out of the gate, sRGB has set the standard for most digital devices and is still the standard colour space for digital output to a screen. Consumer grade monitors purchased today offer up to full sRGB capability. Even entry-level monitors can offer 75% or more of this colour space. But the full colour space itself only takes up about 35% of the CIE standard, so there was a long way to go.
Next up was Adobe RGB, invented of course by Adobe, in 1998. It expanded the “standard” colour space to reflect the fact that printers could now print more colours, and it was aimed at printing. Even so, it occupies less than 50% of the CIE standard. Also, for some strange reason, although cameras, software and printers include that colour space, most monitor manufacturers don’t, or include a small portion of it. I recently purchased a 99% coverage Adobe RGB monitor, and it was fairly hard to find and expensive. But they are available to those who need them professionally or have decided that they are a good investment.
Last up is Prophoto RGB. This colour space was invented by Kodak in 2003, again specifically for printing. It covers about 90% of the CIE standard, which means trillions of colours. To use it, photographs must be stored and edited in 16-bit mode, which creates a problem when using some of the legacy filters in Adobe Photoshop that only operate with 8-bit photographs. This colour space, as noted in the diagram, appears to include imaginary colours that don’t actually exist, at least not in the CIE standard. To my knowledge, there are no monitors or printers claiming to display ProPhoto colour spaces.
All of this is well and good, but what does it mean to you as a photographer? Remember what we said at the start: don’t throw away colour information until you have to. For me, that means the following:
- Always shoot in RAW to collect ALL the data from the sensor.
- If needed, set the colour space in my camera to Adobe RGB, to allow for review of the files before import.
- Import into software using ProPhoto RGB as the defined colour space.
- Set my monitor to Adobe RGB colour space.
- Print using Adobe RGB colour space. Note that if sending to a lab, they will specify the colour space to be used.
- Post on my website or share to social media using sRGB colour space. Note that social media software companies will apply their own often more narrow colour spaces to your photographs as you submit them, so don’t be discouraged if your photograph doesn’t look the same as when you created it.
One question rightly to ask is what will my colours look like moving from one colour space to another? Well-tested and well-designed products such as Adobe’s software ecosystem or high end monitors from ASUS or BenQ will translate the colours as accurately as possible. You may notice some difference in shading, but it should be minor. It’s like translating from English to French – some translation protocols will be better than others. But long-established players will do it right.
Taking this walk into the world of colour has helped me to unconfuse the confusion. Hope it has for you as well. Be well, stay safe. And all the best for the coming year.