Tuesday, September 30, 2008

At the Park Again

At the Park Again, originally uploaded by Gamut's Edge.

Sorry if this bugs my few regular readers that enjoy the aerial photos. My New York to Las Vegas photos didn't turn out as planned. I couldn't get them to color correct. I'm slowly figuring out the nuances of taking photos through Airbus windows. Unfortunately I can't figure out how to remove the color cast from the windshield when there is haze in the air. On a clear day removing the color cast is easy -- add some yellow and red in LAB colorspace. With haze in the air the color cast is not even across the frame and global adjustments don't work. Which brings me to today's photo and a color cast that I know how to fix.

I took this picture of Ella in the shade of a tree. The original had a nasty blue color cast. Shade on a sunny day is always blue because shady areas are lit by the diffuse light reflected out of the blue areas in the sky. To remove the blue I went into LAB colorspace and created an curves adjustment layer where I moved the B channel more towards yellow. To make this change only effect the shady blue cast parts of the photo I built a mask based on a high contrast, inverted, duplicate of the B channel. Pretty tricky huh? If you want to learn how to do this type of thing check out The Canyon Conundrum by Dan Margulis.

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