User Manual

Hover over a node to view its Color Bit Depth setting.
TIP: When working with images that use 10-bit or 12-bit dynamic range or greater, like
Blackmagic RAW or Cinema DNG files, set the Depth menu in the Inspector to 16-bit
float or 32-bit float. This preserves highlight detail as you composite.
Combining Images with Different Color Depths
You can combine images with different color depths in a single composition. When images of
different color depths are combined, the image from the background input of the node
determines the bit depth output, and the foreground image is adjusted to match.
Advantages of Floating-Point Processing
There are two major advantages to floating-point processing that make the additional RAM
requirements and longer render times worth your while. The first benefit is that floating-point
values are more accurate than integer values. The second benefit is the preservation of shadow
and highlight values that go beyond the normal tonal range.
Greater Accuracy
Using 16- or 32-bit floating-point processing prevents the loss of accuracy that can occur when
using 8- or 16-bit integer processing. The main difference is that integer values cannot store
fractional or decimal values, so rounding occurs in all image processing. Floating-point
processing allows decimal or fractional values for each pixel, so it is not required to round off
the values of the pixel to the closest integer. As a result, color precision remains virtually
perfect, regardless of how many operations are applied to an image.
If you have an 8-bit pixel with a red value of 75 (dark red) and that pixel is halved using a Color
Correction tool, the pixel’s red value is now 37.5. Since you cannot store decimal or fractional
values in integers, that value is rounded off to 37. Doubling the brightness of the pixel with
another Color Correction tool should bring back the original pixel value of 75 but because of
rounding 37 x 2 is 74. The red value lost a full point of precision due to integer rounding on a
very simple example. This is a problem that can result in visible banding over several color
corrections. Similar problems arise when merging images or transforming them. The more
operations that are applied to an image, the more color precision is lost to rounding when using
8- or 16-bit integer processing.
1364Chapter – 67 Controlling Image Processing and Resolution