Thursday 4th August 2022
So today we did more colour correction. So we learnt about different contract operations like gamma, colour correct and contrast. Colour correct is worst then gamma as it blows out the shot and gets rid of the detail. However, a gamma operator takes the midpoint of the graph bulges and changes the curve of the line when looking at a colour lookup. Then, the contrast operator rotates around the midpoint of the line changing the white points and black points. It also adds more control points against the line to have more control over the contrast. This makes the contrast operator more natural to use and will modify the pivot used. However, the contrast tool is made by Roy. Local contrast is a tool that can make the shot darker or lighter. It edits the 3/4 tones in the shot. It blushes the curver one way or another. The inverse gamma does it in the opposite way. 1/4 or 3/4 works best in the local contrast. It does nothing to the 0.5 and it's more convenient then to move a slider then draw it each time. It's best to be working on RGBA then all when doing this. You don't have to worry about premulting and unpremulting as there is no alpha. With colour mult you need a lower resolution and you pick up the average values on the plate. You can use an eye dropper tool to get different values but this helps preserve luminance and add stops. Luma/Chroma changes the colour temperature using exposure and changes it. Like from RGB to LAB1 and then you would change it back to RGB. It doesn't change the brightness only makes it more blue. The chroma channels blur then smooth the plate and sharpening the chroma node preserves the luminance. It uses the black points and white points to expand the range then blur. But for a matte you need a value between 0 and 1. Light wrap added over a plate of object you can increase the intensity you put on the foreground than over. It is an alternative tool and gives you a different bleed than other tools. You can control how much light can bleed on the plate and around the object. The light can actually wrap round and doesn't just float like a halo. You can use a switch node to see what different light wrap node to use and this can narrow down the bleed so it's very close to the edge. God rays if using this tool you must always must be checking yourself otherwise it can lead you to make a mistake and the boundary box can grow. The god rays are apart of the background so you must merge to change to plus as it is a lighting pass that you add to the comp.
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