The Imaging window in Indigo features two controls for simple colour correction: White Point, and Colour Curves.

White Point

This control adjusts the white point of the image via chromaticity coordinates x and y. There are a number of presets to choose from, with the option to edit the white point completely manually.

Colour Curves

Colour curves offer great control over tone and colour, right inside Indigo. There are curves for each RGB channel, as well as an Overall curve for control of overall brightness and contrast.

For each colour curve, the x coordinate (e.g. distance along the horizontal axis to the right) is the input value, e.g. how bright a pixel value is before it is transformed by the colour curve. The y coodinate (e.g. distance along the vertical axis upwards) is the output value, e.g. how bright a pixel value will be after it is transformed by the colour curve.

In this example image we are using the colour curve to generate more contrast in the image - in particular to make the blacks blacker and to saturate the brighter grey values towards white. This is achieved by using an S-shaped curve.