A lot of the examples we see online for Pixel Bender (previously codenamed Hydra) are crazy visual effects. While they’re amazing for certain visual effects (mostly due to the processing speed), finding real life use is harder. I’ve had the need for a similar-to-photoshop levels filter multiple times, if nothing else for preprocessing a bitmap for further analysis. Turns out creating something like this with Pixel Bender is really simple and even better; it’s blazing fast.

If you’ve read my previous articles you know that I’ve already written a prototype for the levels filter (geesh, it’s almost a year ago!). Well, back then Pixel Bender was called Hydra and the code written isn’t compatible with today’s version anymore. I addition to that we weren’t able to export stuff, it just ran in the Hydra toolkit. Today I updated the code and exported it as a .pbj that can be used in Flash.

I’ve made a small example with a couple example images with the contrast reduced. You’ll need Flash player 10 to play with it. If all you see is white download the plugin from Adobe labs.

A couple pointers on the example: Clicking a histogram will automatically balance it. Double clicking will reset it to 0-255. Clicking the image will load a new image. In photoshop you can choose to either modify the luminosity or the individual channels. Here i enabled you to modify both at the same time, but this means that if you modify all 4, the automatic mapping won’t be correct anymore (the histogram in the bottom left corner will show the result of this). I could make it understand this, but since it’s just a proof of concept i think this is fine. Also gamma isn’t supported at the moment.

The source is of course available:

• levels.pbj (file to load in flash)
• levels.pbk (source for levels filter)
• pb_levels.zip (everything, including the example with the source)

Do you have other real life uses for Pixel Bender?