UPF Explore Chromatic Induction

UPF have been conducting experiments into chromatic induction. Chromatic induction is a visual phenomenon where the hue of image regions is impacted by the hues of adjacent regions. Induction always plays some subtle role in informing the appearance of objects in any natural image or visual scene. An important detail for motion picture delivery is that the direction and magnitude of this effect can be variable as a function of the spatial frequency or the distance at which the pattern is viewed. This is part of the reason why image content can have a different appearance on different sized screens. To investigate this, UPF have performed psychophysical experiments to identify the effect's disparity between patterns of two different sizes, representing mobile and cinema viewing scenarios, and to propose an image processing method to compensate for it such that the appearance of content on any screen size can be related back to the mastering display.

Test stimuli used in our chromatic induction experiments.

In this example, the turquoise center ring of the large pattern is physically the same color as the greenish center ring of the smaller pattern immediately to the right. Induction, and its dependence on pattern size/viewing distance is the cause of the color disparity. By zooming in and out of the test pattern, one can observe the induction effect shift as a factor of presentation size. The pattern on the far right represents the smaller pattern passed through our corrective method. It can be seen that the ring is shifted back towards the turquoise colour of the original, large pattern.