Broadcast Safe Tool			Color Correcting with CC Basics
Chapter 20, Color Correction

Logarithmic data is automatically converted to linear data on import by applying a 1D LUT to the imported image. However, if you need to work in log space, you can modify both the display and image data by using the Log and Delog tools.

The Log and Delog tools let you transform between linear and log color space. The Log tool transforms from linear to log space and the Delog tool transforms from log to linear space.

The log space in Toxik is very similar to that used by Cineon encoding, but it does not clamp high dynamic range values, and it is scaled with respect to the Cineon codes. That is, a Cineon code of 1023 corresponds to a value of 1.0.

The transformations can be controlled with the negative film gamma, the Cineon reference, and the linear reference. These reference points are expressed in units of the log space described above. You can display their value either as raw or as Cineon codes.

Modifying Negative Film Gamma, Cineon Reference, or Linear Reference Levels

The transformation between log and linear color spaces is controlled by three parameters: negative film gamma, Cineon reference, and linear reference. Gamma controls the contrast, while Cineon reference and linear reference establish a correspondence between points in the two color spaces. The Cineon code, specified as the Cineon reference, is transformed to the value specified as the linear reference. For example, you may want to base the transformation on the 90% white card and specify a Cineon reference code of 685 and a corresponding linear reference value of 90.

Note: All Delog and Log parameters are animatable --see Setting Keys Manually and Validating and Applying the Expression String.

The white reference is mapped to 0.9 in linear space. Cineon codes above reference white are mapped to values above 0.9, however, these values can be greater than 1. This tool does not clamp to 1, so there is no loss of information.

All incoming pixels with values between 1 and 95 produce black pixels.

Note: All channels are linked by default.

• Do one of the following:

  • Drag the red (R), green (G), or blue (B) channel fields to the right to increase, or to the left to decrease, values uniformly on all three channels. Alternatively, you can also drag the luminance (L) field to achieve the same result.

  • Select a single channel that you want to modify by deselecting the Lock button.

    Drag the red channel field to the right to increase, or to the left to decrease, the level of the red channel.

    The green and blue channels are not affected. However, the overall luminance field updates to reflect the change.

  

Note: You may also type values into the channel fields and press Enter. In the case of modifying all channels uniformly, when values are typed into any field, the other fields update. The luminance field will update regardless of which method is used to modify the values.

The trackball allows you to modify levels with a more freestyle, intuitive approach. The trackball emulates a typical 360-degree color wheel that can be dynamically changed by dragging the center of the color wheel. Consequently, the effect on the red, blue, and green channels is predictable.

For example, dragging the trackball towards the red portion of the color wheel increases the value of the red channel, but decreases the values of both the blue and green channels, and adds blue and green to the shadows and midtones of the image.

Modifications made using the trackball are cumulative; each movement of the trackball is added to the previous one. The trackball changes color to reflect the degree of change.

• Drag the trackball to modify levels in the image.

  Note: To reset the trackball, channel, and luminance levels, select the Reset button below the trackball or the Reset button in Tool Options area on the right side of the UI (this button resets the entire tool).