What is a color space? Why do I need to know it? How do color spaces tie into my understanding of cinematography as a film student? These are hopefully some of the many questions you’ve asked yourself at one point or another while you were working with color spaces in post production. From the get-go, what you do need to know is that each of the color spaces that will be mentioned in this article are industry standards that must be adhered to if you want your audience to see your images the way you intend.
Section I: The Electromagnectic Spectrum
To understand color space, you first need to understand the electromagnetic spectrum. Our eyes, which are biological miracles, can see a small slice of a vast visible spectrum; this spectrum is called the electromagnetic spectrum. It consists of only seven main colors: Red, Orange, Yellow, Green, Blue, Indigo and violet (ROY G BIV). The human eye can see roughly 10 million variations of those seven colors.
Ok, but what about black and white? Aren’t those colors as well? Black is the absence of color (sucks in color like a black hole), while white is culmination of the entire color spectrum (reflects/bounces light).
Section II: How Color Space Was Born
In 1931, the Commission Internationale de l’Eclairage (CIE) aka the International Commission on Illumination created the CIE 1931 Color Space, the most accurate representation of what and how many colors the human eye can see; there were slight revisions in 1960 and 1976 (adding more accurate calculations to the charts and sectioning it off into color portions), but most people in the film and photography industry still adhere to the 1931 chart. All color spaces are located inside the 1931 color space except for the Academy Color Encoding System (ACES), which is still in beta testing right now.
Section III: Color Gamut
A gamut is a defined as an entire range or series of related things. A color gamut is a range of visible colors a device can capture (camera) or reproduce (monitor);. Because each camera captures colors in its own unique fashion, we photographers/cinematographers can’t accurately ascertain which colors the device is actually reproducing unless those colors are physically defined in a standardized space. This is where color space comes into play.
Section IV: Color Space
A color space is a standard/mapping system that takes those colors the camera reproduces and defines them within a space that we can all see. Some examples of color Spaces are sRGB (Internet Standard), Adobe RGB (Photography Standard), REC.709 (Television Broadcast Standard), REC.2020 (UHD Not Standard Yet) and DCI P3 (Cinema Standard). The larger the color space, the more the gamut can expand.
Section V: A Brief History of sRGB
In the late ’90s the Internet was still on the rise, and color uniformity across monitors in terms of color space was still a wild west. In light of this issue in 1996, Hewlett Packard and Microsoft decided to create a color space/standard called SRGB; this color space is still the world-wide standard for all Internet images and videos. The two companies decided to use consumer-grade CRT (Cathode Ray Tube) monitors as their main reference/inspiration for the SRGB color space; the reason the color space is so limited is because the monitors they took their inspiration from were so limited. As display technology advances in the range of colors it can display, so does the color space. Adobe RGB was released in 1998, and the size of the color space was twice the size.
Section VI: What Occurs When Placing a Larger Color Space Into A Smaller One And Vice Versa
Let’s say you want to place an image with an sRGB color space into a DCI P3 color space. What’ll happen is the colors will look oversaturated, almost neon. This is occurring simply because the smaller color space is attempting to spread its small tonal range across a larger one; the small amount of colors can’t replicated the complexities/nuances of the wider tonal range, so they end up brightening up instead of actually replicating the correct colors.
Now, you try placing a DCI P3 image into an sRGB color space. What occurs is opposite. Color becomes desaturated, and you lose the small complexities/nuances/details that the colors once had. Because the wide tonal range can’t be replicated as accurately as it should, colors such as bright red will become a muted orange. The vibrance and richness are lost and colors end up losing their definition.
Section VII: The Color Space To Place Your Footage Into In DaVinci When Your Are Grading
If you’re shooting RAW video, you won’t have to worry about color space when it comes to the acquisition phase (acquiring the image), but with a compressed image, color space matters because the footage will be confined to a color space during the acquisition phase; once it’s been confined there’s little you can do to change it. Now, when it comes to placing your RAW footage into a color space, it really depends on what your output/delivery is going to be. If you’re putting your images onto the Internet, you’re going to want to grade in sRGB. If you’re putting your images out for broadcast use, REC.709 is the way to go. If you’re delivering to UHD BluRay, REC.2020 is the color space to go to. Finally, if you’re sending your images out to digital-cinema-standard projectors, you’re going to want to use DCI P3.
Without color spaces, universal viewing conformity would not be possible. Use the color spaces accordingly, and the audience will see the footage as you intended while grading in post.