From colorist and cineaste extraordinaire Will Tordella, a new manifesto on the emotional content hidden within the color spectrum of a video image: “Red Depth”. Knowing Will, I suspect his “Red Depth” blog will become a must read.
Here’s an excerpt from his first post:
The problem is that human perception of the color green is not as receptive as our appreciation of the red spectrum.
The reason is red’s long wavelength and that our eyes respond more to long wave ranges. This results in wrestling with it. In the video realm this has some very practical outcomes. (Most of the following can also be found on Wikipedia.)
For us to perceive the colors as equal, the green and blue are compensated for in the video signal. This causes red to have a “weaker” representation in the signal and during its life cycle with signal deterioration red suffers first which results in increased noise and smear.
In the past with analog signals the green was prioritized color. The issue with the red component is the same for analog as well as a compressed digital signal. The red’s area is reduced, hence it is more pixelated. Problems also can arise with focus when shooting in predominately red light.
And so we have a little “Red Death,” if you will, like the light of a star begun it’s descent to the end of life.
Things get more technical here. (But don’t let it put you to sleep. Red Death is Life and Death when we’re talking about the effect of an image on audiences.)
Red Death is not an illusion – it arises from something called chroma subsampling. Most video codecs do not represent color in full resolution as a way of achieving greater compression by taking advantage of the way that the human eye is more sensitive to brightness (“luma”) than color (“chroma”).
It’s slightly more complicated though: the brightness is actually made up of the sum of the three color components: Red, Green and Blue. And they’re not encoded as RGB, that would be require more bandwidth, they’re encoded as YUV. Y corresponds roughly to the green component, and the U and V are Y minus the red component and Y minus the blue component (a gross approximation, actually – if you want the whole formula look here).
In most codecs, the U and V components are sampled at a lower resolution than the Y. This is expressed in the three-way ratio you often see if you hang around video forums too much, e.g. 4:2:2 or 4:2:0.
A common example of this notation is in the codec name “ProRes422” the 422 bit comes from 4:2:2 meaning for every a 4×2 rectangle there will be 4 Y samples in each row 2 UV samples in the first row (half the horizontal resolution) and 2 UV samples in the second row. So ProRes422 has half the chroma resolution of the luma.
This means the red channel on its own has one quarter the resolution of the overall picture.
Our eyes literally have a greater physical capacity for immediately responding to the color red than they do any other color.
So actually that is more breadth on the red side then, isn’t it? It is therefore our responsibility (as can be true outside of the color spectrum) to provide the depth. We must plumb the depths as it were. Red seems to beckon us like a siren of the rainbow, with its sweet, sultry song.
So let us accept that single invitation as an excuse to stare deep and longingly into the whole sumptuous image. Let us be seduced, and perhaps provide some flirtation ourselves. Let It passionately and boldly course through our veins (as if we had much choice.) Let it bleed into our psyche. The color is caught up in life and death. It gushes, it spurts, and it imbues. It vibrates, it glows and it captivates.
Let us plunge into the whole spectrum of possibilities. Cinema, at it’s heart is moving imagery given life. We give it life, and we receive life from it. The best can fill it in and from every direction. We are sat down to observe, and so we shouldn’t take that lightly.
Look and listen well. I am best at looking.
So here it is. We will take in all of it. We will obsess. We will squint. We will ponder and mull. We will lust. Review, re-watch and freeze-frame. Follow the motion. Follow the emotion.
We will pull this dying light back from possible oblivion, and see what it reveals. We will listen. Turn your best ear and lean in.
So, that is to say, let’s watch some movies.
(minor editing and reformatting)
Check out the full post on Will’s Google Plus. It goes into great depth on the use of color on the TV Show Hannibal.