The rendering of the gray axis for the Perceptual intent is impacted by the color of the print substrate. For instance, if a paper contains optical brightener (results in a high bluish -b measurement value), the gray axis in the profile will be rendered towards bluish. If a paper is more yellowish, the gray axis in the profile will be more yellowish.

The ‘Neutralize gray’ option allows to compensate these color shifts in the gray axis. The higher the value for the compensation, the visually more neutral the resulting gray axis in the profile will appear. For instance, if the value is set to 100, the gray axis for an optically brightened paper will appear more neutral (more yellowish) rather than bluish.