By Lesa Snider Macworld.com | on August 17, 2009
Company: George DeWolfe
Pros: Easy to use interface when run as a script; instantly adds life to flat images.
Cons: Difficult to use as a plug-in filter.
The Gamma slider can be used to adjust the shadows in your image. Just drag the slider to the left to make them darker or to the right to make them lighter. The Saturation slider controls color intensity and should be used after adjusting the first two sliders.
When you’re finished adjusting the sliders, close the dialog box and create a Gradient Map adjustment layer to adjust contrast. Since contrast is the one part of the process that’s subjective, a Gradient Map gives users the ability to adjust it to their liking. If you’re working with a colour image that you want to remain in color, change the blend mode of the Gradient Map adjustment layer to Luminosity (leaving it set to Normal produces a black and white RGB image).
If you run PercepTool as a script, you get this handy interface.
The PercepTool plug-in can also be accessed from Photoshop’s Filter menu, but this method summons no interface. Unfortunately PercepTool won’t run as a Smart Filter (though when working on 32-bit images, few filters do), so it’s best to make a duplicate of your image layer first. The PercepTool plug-in runs at 100 percent, so in the absence of an interface you’ll need to use the Edit > Fade command to adjust the strength. You’ll also need to add a Gradient Map adjustment layer to adjust contrast. With the lack of interface and the added steps of duplicating the original layer and fading the filter, it makes no sense to use it in this manner. Instead, stick with running PercepTool as a script.
Here you can see the difference between a regularly adjusted black and white image, and one adjusted with PercepTool. Notice the increased detail in the artifact in the foreground.
If you want to take your images from flat to full of life in a hurry, this plug-in does the trick. Sure you could try adjusting Curves and Gamma manually, but that still won’t produce the same results. If you’re a seasoned Photoshop jockey looking for a challenge, download the free 30-day trial and see how close you can get; I think you’ll be reaching for your credit card in the end.