Apple Shake 4 - Manual (Page 632)

632 Chapter 23 Color Correction
To analyze an area:
1 Attach the PixelAnalyzer node to an image. Double-click the PixelAnalyzer node to load
its image into the Viewer and its parameters into the Parameters tab.
2 Position the analysis area box in the Viewer to examine the necessary area of the
image, and adjust its size as necessary.
Note: To animate the box, use the Viewer Autokey button, or use an expression to
assign tracker data to the areaX and areaY parameters of the analysis area. Otherwise,
the box remains stationary.
3 To create several analysis areas, use the Add button in the lower portion of the
parameters.
4 Verify the frame range in the analysisRange parameter.
5 Press the Analyze Forward (or Analyze Backward) button in the Viewer.
The analysis begins. Each analysis area (controlled by the visibility toggle by the
areaName) grabs color values within its area and calculates the average, minimum, and
maximum values for that area.
To delete an analysis area, do one of the following:
m In the Viewer, select the box (click the box), and then click Delete in the PixelAnalyzer
parameters.
m In the PixelAnalyzer parameters, click the areaName value field (highlighted green) and
click Delete.
To save the data of an analysis area:
1 Click the Save button in the lower portion of the PixelAnalyzer parameters.
The “Save pixel analysis data to file” window appears.
2 Select or create the directory to store the saved the data, name the file, and click OK.
Using the PixelAnalyzer to Correct Uneven Exposure
The following examples show how you can use the PixelAnalyzer node to obtain image
data that is used to correct the exposure of a shot that dynamically brightens or
darkens. The goal is to even the exposure of the image out so it doesn’t change. These
examples illustrate the power of expressions in Shake to automate complex operations.