Viewing Proxies			Saving and Loading Presets Using the Presets Lists
Chapter 12, Colour Grading: Basics

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Sampling Colour Values

Viewing Colour Distribution

While you colour grade, you can use different tools to view and analyse colours. Use the Analyse tools to view the colour distribution in the current frame. Use the Pixel Analyser to sample the image to compare colour values used in the input (original) and output (result) images.

Sampling Colour Values

When you generate mattes, modify shots, or match colours between shots, you can sample the current image in the Player. When you sample the image, the input and output colour values are displayed in the Pixel Analyser.

The sample will appear in the Curves menu so you can view input colour values when you refine the image. R, G, and B colour values are plotted separately on the RGB curves while the combined RGB colour value is plotted on the Hue, Saturation, Lightness, and Luminance curves.

When you create a key, you must sample the image to set tolerance and softness values. See Creating a Secondary by Keying a Range of Colours.

1. Select the frame in the shot you want to sample.

2. Click Pixel to display the Pixel Analyser.

   

3. In the Player, do one of the following:

   • Drag the image to sample a single pixel in the image. You can drag through the image until you locate the pixel you want to sample.

   • Alt-click to sample an average taken from a range of colours in the image.

   The sample appears in the Pixel Analyser.

   

Viewing Colour Distribution

There are a variety of Analyse tools that you can use to view the colour distribution in the current frame. Analyse tools are useful when you want to determine the original structure of the image and see how a grade transforms the colour space.

You can display up to three Analyse tools at one time. Use these tools to help match colours, view the colour distribution, adjust shadows and highlights, and ensure that broadcast and other standards are met. You can display the following Analyse tools while you colour grade.

Histogram--Displays the distribution of image pixels across the luma range for the R, G, and B channels.

Waveform monitor--Displays the R, G, B channels separately or together as a waveform.

Vectorscope--Displays the distribution of image pixels across luma and hue ranges.

The Analyse tools show the changes you make to the colour content in a shot. Each tool is dynamically updated to reflect your changes as you modify the image.

Note: The histogram, vectorscope, and waveform monitor do not dynamically update if GPU processing is enabled. They retain the colour distribution of the image prior to GPU being enabled.

• Display up to three Analyse tools to view the colour distribution of the image.

  Press:	To display:
  Alt+1	The RGB waveform monitor.
  Alt+2	The RGB histogram.
  Alt+3	The luminance waveform monitor.
  Alt+4	The vectorscope.

  
  

  

  Waveform monitor (with RGB channels displayed separately)

  Histogram

  Waveform monitor (with RGB channels displayed together)

  
  

  Note: Right-clicking over any of these monitoring tools either zooms you in, or adjusts the tool's luminance value.

1. Press F5.

   The last used view is displayed--either split view or multi-view. Split view displays two frames split in half while multi-view displays the entire frame of one or more shots.

2. If multi-view is displayed, press F4 to activate split view.

   The current frames on Playheads A and B are displayed either horizontally or vertically, depending on the last displayed orientation.

3. Press F1 or select A from the Playhead button and then select the shot in the Storyboard.

   The shot you are working on is assigned to Playhead A.

4. Press Alt+2 to display the histogram for the shot assigned to Playhead A.

5. Press F2 or select B from the Playhead button.

   The shot is assigned to Playhead A.

6. Press Alt+2 to display the histogram for the shot assigned to Playhead B.