This effect was generated in Filter Forge, a Photoshop plugin that allows you to create your own filters.
This filter can adjust the brightness tones of an image.
It works similar to the Tone Curve component, but you can describe your own "curve" (so to speak). It is also similar to PSP's "Curves" adjustment – but this filter preserves the color.
Tips:
The Position parameters determine what tones the Light parameters affect. Lower position settings will cause the Light parameter to affect the image's darker tones while higher positions correspond to the lighter tones.
And if you do want to change the Position sliders, be sure to have the "Positions On" box checked. (But you can do a lot with just the Light parameters using the default positions – i.e. keeping the Positions box unchecked.)
tone curve curves control levels threshold contrast lightness brightness saturation desaturate metal chrome elevation gradient photo correction
This filter has earned its author one of our rewards. They are given to the authors of popular filters and include a free copy of Filter Forge.