PercepTool 2™ is a Photoshop add-on suite that performs Tone Mapping and Perceptual Effect operations on digital photographs.

Compatible with both Windows and Mac platforms in 32- and 64-bit processing, it operates in Photoshop CS4 and CS5 (Photoshop Extended required for 32-bits/channel). PercepTool 2™ works with both B&W and Color images in 8-bits, 16-bits and 32-bits. Completely revised and updated, PercepTool 2™ includes a new interface for the Perceptual Effect routine that now includes Exposure and Contrast adjustments instead of using Photoshop tools.

The Perceptual Effect adjustment has been redesigned to operate faster and to protect the highlights. In addition, PercepTool 2™ now includes Equalizer™, a superior multi-contrast Tone Mapping interface. Included is a Histogram with both Levels and Ansel Adams Zone System scales. LiveView™, the ability to work on the image itself and not a preview, is unique to PercepTool 2™.

I invented PercepTool™ to solve the problems mentioned in B&W Printing, 2009, published by Lark Publications. Basically, the tool works with the luminance image we get from the camera and corrects it to look like the luminosity percept produced by the visual cortex of the brain.

The idea behind PercepTool™ originated in 1978 with Ed Land’s essay (see page 21 in the book) and continues with my ongoing research in lightness perception. At this point it is nearly impossible to create this percept effect manually in Photoshop. So, I set out to make a Photoshop plugin that would accomplish this difficult task with the most sophisticated tools available to us in digital imaging science. In the software, one click changes the luminance image into the luminosity percept of the visual cortex. For those of you making that one click, remember that the development time and research involved behind that click took 30 years. PercepTool™ is used in combination with one or two other Photoshop tools, most notably the Gradient Map.

How does PercepTool work?

PercepTool takes the image made in the digital camera sensor (also called luminance image) and changes it into what our brain actually perceives. The luminance image consists of 2 sub (intrinsic) images: reflection and illumination. The reflection and illumination images are separated from the luminance image in the visual cortex of the brain, processed and recombined into what is known as the percept, or the image that we actually perceive. We call this image luminosity. Most of the changes are due to differential recombination of the edges in the image and optimization of tonal values. 

Here is a demonstration of the process: