Game Development Reference
Compander sandwich; or rather, an 8-bit sandwich on HDR
Compander bread (Fig. 21.8).
Figure 21.8 The Effect Controls
panel with the “HDR Compander
sandwich.” Note that Fast Blur
does not need to be part of the
“sandwich” because it operates
at 32 bits.
On the instance of the HDR Compander effect applied before
8- or 16-bit effects, set the Mode value to Compress Range. Set
the Gain value to the highest brightness value on the layer. For
this HDR layer, my red value is set to 3, so I set the Gain property
to 3 as well. You can also use the Gamma property to adjust the
levels and luminance a little.
Then you apply another instance of the HDR Compander
effect, and stack it after all 8- and 16-bit effects. This time, set
the Mode value to Expand Range. Set the Gain value to the
same number you used for the compressing version of the HDR
Compander effect. In my case, I'm going to use a Gain value of 3.
When you're done adding these instances of the HDR Compander
effect, your HDR color will return (Fig. 21.9).
Now, I realize these results are not without fl aw. Some of the
original subtle nuances are lost through this process. Although
we would get much better results if all effects could pro-
cess in 32 bits, this effect is a valuable work-around until that
The HDR Highlight Compression Effect
The HDR Highlight Compression effect is very simple. It
compresses 32-bit color values to conform to 8-bit color val-
ues. That's it. There is an amount slider that basically functions
as a Blend with Original parameter that we see in so many other
effects. But it does pay to note that the values really do become