More Complex Compositing

rThe previous series showed how to match footage/ images of similar colour/ lighting but what about those that are different completely in contrast. Take the example below as an example. Looking at the values in the info panel- you can see that the colours are really saturated.

comp12The tutorial briefly explained different ways of replicating the colours onto the cube- using a gradient in a levels layer or creating a custom object (cube in this case). The second option is the one being shown- so it was advised to set up the 4 views in 3D space, turning three into each of the colour channels- one for Red, Blue and Green.



Matching Levels with Proportions

The process shown will be able to use to prevent noodling or messing around with lighting in 3D – and can be used to match any object to a scene, as long as there is no major differences in lighting fundamentals/ directions.

In this tutorial, the match will be made by using a reference object to the scene. In this case- a cube made from three solids- one 100% or white, one 30% or grey and one 0% or black.

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The next thing is to match the values of the cube- to the values of another object in the scene. In this street scene- there are things that are obviously white- in this case the street sign that the cursor is on. The values are shown in the info panel.

Screen Shot 2016-11-28 at 13.59.13.png

Clicking on different white objects shows the values. They all vary, however they have something in common. The red value is the lowest and blue is the highest values. The green is about 15% higher than red in each case and the blue is around 25% higher than the green.

These values are going to act as the output white values for each RGB.

Screen Shot 2016-11-28 at 14.08.42.png

To find the black values, we look at another reference in the image and the replicate these in the output black channels. Then, you can copy and paste the values onto the original cube. Another thing to look at is matching the shading under the original statue cube – using a slider. However, I don’t need to worry about this just yet as I can replicate this in my own lighting.

Slam to Test the Match

The tool used here to evaluate the composite in our scene will be the expose slider. As the exposure slider is pushed upwards, a lot of detailing previously lost appears. As you can see- the blacks are no where near as dark as they need to be, a lot of grain is visible in the background etc. Also, as the exposure is lowered. It is apparent that the bright elements in the foreground are the self illuminating ones, whereas in the cubes case, it is the red faces.

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Clicking on the iris icon resets the exposure to 0%.

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Under the RBG input blacks at a higher exposure, these differences in the input black can be fixed though fixing the histogram.

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This process known as ‘slamming’ allows to see the sins hidden in the images- the shadows and levels being fixed.

Developing an Eye for Saturation

Premise- the foreground and background are matched but they don’t look right! This problem may lie with the saturation.

First, a second levels layer is created, to view the histogram. As the input white contrast increases, the three spikes below get further apart. The further apart the RGB are, the more saturated they are.

Screen Shot 2016-11-28 at 14.37.14.pngIf a black and white filter is moved above the histogram, you can see the differences are gone between the RGB.

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As the tint increases, these points aren’t as together, making it blend in more. The clump of red represents the red of the rubix cube.

Desaturation with Tint

Tint is used instead of the hue/saturation menu- why? And so begins the Nerdy detail into what the difference is between the two.

Shown below is simple graphic with red, green, blue, magenta, cyan and yellow. As the saturation increases the colours completely fade. This is because as they are saturated, they become pure grey. Technically, this is correct. However the eye views these differently.

Screen Shot 2016-11-28 at 14.46.39.png

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Next lets look at the tint effect. The tint effects takes into account that you eye sees green as brighter than red, and blue as darker. So yellow, being the opposite of blue, is perceived as the darkest . The level of tint can be died back, but the contrast remains. As you compare the tint to the saturation/ hue levels, you can see the difference – the tint very has more of a richness.

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