Apply the hdr compander effect, Hdr highlight compression effect – Adobe After Effects CS4 User Manual
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USING AFTER EFFECTS CS4
Effects and animation presets
Last updated 12/21/2009
Apply the HDR Compander effect to a layer once in the effect stack above low-dynamic-range effects, and once below
low-dynamic-range effects.
Because the first instance of the HDR Compander effect compresses the range of values through sampling, some
precision is lost. For this reason, use the HDR Compander effect only if you accept the tradeoff of some precision in
values for the sake of high dynamic range.
This effect works with 8-bpc, 16-bpc, and 32-bpc color.
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Color depth and high dynamic range color
Apply the HDR Compander effect
1
Apply the HDR Compander effect to a layer in a 32-bpc project.
2
Select Compress Range for Mode.
3
Set Gain to the maximum value to be represented in the compressed range—that is, the highest white value in the
image. Don’t set Gain too high; the more of the 16-bpc value that you use for highlights, the more compressed the
midtones (the majority of the pixels) will be, and the more data is lost in this process.
4
Set Gamma. Gamma affects the distribution of values in the range, allowing more precision in specific areas of the
range.
5
Apply whatever low-dynamic-range effects you choose to the layer.
6
Apply another instance of the HDR Compander effect to the layer. Make sure that the second instance of HDR
Compander is ordered after (below) any 8-bpc or 16-bpc effects you’ve applied.
7
Select Expand Range for Mode for the second instance of the HDR Compander effect.
8
Set Gain and Gamma to the same values as set in the first instance of the HDR Compander effect.
A more convenient way to use the HDR Compander effect is to apply the Compress-Expand Dynamic Range
animation preset. This animation preset consists of an expression and two instances of the HDR Compander effect:
The first instance has Compress Range selected, and the second has Expand Range selected. The expression automatically
sets the Gain and Gamma for the second instance to be the same as that which you set for the first instance. Insert
whatever low-dynamic-range effects you choose between these two instances of the HDR Compander effect.
HDR Highlight Compression effect
The HDR Highlight Compression effect compresses the color values in a high -dynamic-range image so that they fall
within the value range of a low-dynamic-range image.
Adjust the amount of compression by setting the Amount property for the effect. If the Amount value is set to 100%,
color values are compressed so that no pixel has any channel value outside the low dynamic range of 0.0–1.0. At
Amount settings less than 100%, the effect can still bring some detail into the visible range from highlight and shadow
regions.
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