Source Space determines the input color space of the image. Leave this at "No Change" if you want to just add Gamma using the Output Space control.

In Fusion 6.1 new options have been added here.

The DCI-P3 color space is most commonly used in association with DLP projectors and is frequently provided as a color space available with 2K DLP projectors, and as an emulation mode for 10 bit LCD monitors such as the HP Dreamcolor. This color space is defined in the SMPTE-431-2 standard.

The custom gamut allows the artist to describe the color space according to CIE 1931 primaries and white point, which are expressed as x\y co-ordinates, as well as by gamma, limit and slope. For example, the DCI-P3 gamut mentioned above would have the following values if described as a Custom color space. Red Primary : 0.68, 0.32 Green Primary : 0.265, 0.69 Blue Primary : 0.15, 0.06 White Point : 0.314, 0.351 Gamma : 2.6 Linear Limit: 0.0313 Linear Slope: 12.92

To understand how these controls work you could view the tool attached to a gradient Background in Waveform mode and observe how different adjustments modify the output.

Output Space is the converted gamut to the desired color space. Leave this at "No Change" if you want to just remove Gamma using the Source Space control.

Select these checkboxes to do the gamut conversion in a linear or non-linear gamma, or simply remove or add the appropriate gamma values without changing the color space.

Selecting this checkbox will cause the image's pixel values to be divided by the alpha values prior to the color correction, and then re-multiplied by the alpha value after the correction. This helps to avoid the creation of illegally additive images, particularly around the edges of a blue/green key or when working with 3D rendered objects.