GENERAL

The Balance menu reveals two sets of color adjustment sliders - Offset and Pre-Gain - and offers advanced functions for auto-grading and match-grade.

COLOR BALANCE SLIDERS

The Offset and Pre-Gain sliders are used to affect an overall change to the image before any of the Color menu adjustments are applied. In this way, they can be used to adjust and/or neutralize the image’s color so that the subsequent color adjustments properly track throughout their range.

For example, if an image is skewed slightly into the green, a Pre-Gain and Offset adjustment can correct the skew. This is done so that Gamma adjustments do not skew the image further into the green as the Gamma is increased.

OFFSET

The Offset controls are similar to the traditional Hazeltine printer-light controls from optical color timing. By adjusting the sliders, you can shift the overall image towards a certain color or luminance. The total range of color and luminance remains the same but the values are increased or decreased by the offset amount.

The sliders can be adjusted by clicking and dragging the hash mark indicator within the slider. Use the Quick Key: Shift to alter the responsiveness of the sliders.

Clicking on the small arrows at the top and bottom of each slider adjusts the slider by a preset amount.

Note: The Offset can be calibrated to match the specifications of a film lab by adjusting the Luma Weight and Print Light settings in the Config/Options menu of the Matrix. This menu is covered in detail later in this chapter.

You can also adjust the sliders using the Numerical Slates at the bottom of each slider. These behave like all other Numerical Slates in SCRATCH.

PRE-GAIN

The Pre-Gain adjustments allow you to scale the individual color channels around preset pivot points, which are determined by the black and white level pivot point (described in the PIVOTS section below). Pre-Gain is typically used in conjunction with the Offset adjustments to balance the overall luminance, red, green, and blue levels in an image. This has the effect of neutralizing the color balance of the image in preparation for further manipulation.

SLIDERS

Both the Offset and Pre-Gain settings can be manipulated using Slider controls or - when disabling the Slider option - by using Tracker Ball controls. The Slider on/off option is stored as a user setting.

GRADE TOOLS AND SETTINGS

AUTOGRADING

You can use Auto grading to adjust the Offset and Pre-Gain values to automatically fit an image into the selected range determined by the pivot color pots.

Note: If the Set Master button is enabled, Auto grade sets the Master adjustment as well as the individual RGB channel values.

MATCH GRADING

Match grading can be used to modify the RGB levels on one image to align, or match, with another image based on a Source and Target RGBv alue that is sampled from each image.

To use the Match Grade function, first select a Source color by clicking on the Source color pot; you then use the Color Picker and/or the Color Selection Palette tool to select a color from the source image that will be used as the RGB reference to be modified.

Next, select the Target color pot and use the Color Selection Palette to choose the destination color.

Pressing the Match Grade button then adjusts the RGB levels from the Source color to align with the Target color.

While working with Match Grade, you can use the Histogram view(discussed in Chapter 05 - The Player) as a guide for visualizing the Source and Target RGB values. After selecting the Source color you will see the Histogram displaying a lower split. This indicates where your Source Levels fall across the Luminance and RGB ranges.

After selecting the Target color, the Histogram displays a second set of markers, indicating the RGB values that represent how the levels will be shifted if a Match Grade is executed.

INVERT, RGBA

The Invert button inverts the color channels of the image. All color adjustments are done after the inversion.

COLOR- AND ALPHA CHANNEL MIXER

With the color-channel mixer you can alternate the position of red,green, blue and alpha components to handle and process e.g. BGR images instead of regular RGB formatted images. Using the channel=0 option you can exclude a certain channel all together.