Modifying Deep Data

Nuke allows you to color correct deep images as well as modify them using expressions.

Color Correcting Deep Images

The DeepColorCorrect node applies the color correction to each sample at each pixel.

There are control sets for adjusting shadows, midtones and highlights, as well as a master set for adjusting all these at once. You can use the lookup curves on the Ranges tab to control the range of the image that is considered to be in the shadows, midtones, and highlights. For more information about the basics of color correcting, see Working with Color.

Tip:  Make mattes by setting the gain value for your alpha channel to 0 and setting the offset value for the alpha channel to 1 in the range you want a matte for.

Adjusting the Effect of Deep Color Correction

On the Masking tab you can set the point among the deep samples where the effect of your color correction starts and finishes.

1.   Check the limit_z box to activate the zmap tool.
2.   Adjust the trapezoid so that the A delimiter marks the depth where you want the color correction to start, B and C mark the length of the full effect and delimiter D indicates where the effect stops. Zmap tool’s y axis, therefore, indicates the amount of the effect, and the x axis is the range of your depth samples.
3.   Use the mix control to adjust the overall mixing between the color corrected result and the original image. Zero value is the original image, and value 1 is the full color correction result.

Modifying Your Deep Images with Expressions

You can use the DeepExpression node to run Nuke expressions on deep data. Use the controls in the properties panel:

1.   There are four fields for temporary expressions, just like in the normal Expression node. These can be useful if you need to use a long expression in several fields and want to assign that expression temporarily to a variable. Enter the variable name to the left of the equals (=) sign, and the expression to the right. You can then use the variable name to represent the entire expression in the expression fields for the channels.
2.   In the chans0 - chans3 dropdowns you can then specify which channels you want to create expressions for. This adds or removes expression fields below.
3.   You can then enter your expressions for the different channels in the channel expression fields.

For more information about expressions, have a look at Expressions.