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Using Adobe PhotoShop's "Auto Contrast" for haze removal.
Another way to clear up hazy, cloudy looking pictures.
Dull, hazy looking pictures have always bugged me... and it's especially a problem with outdoor photography. Some days are worse than others. Mist, smog, smoke, haze, fog, high humidity, overcast conditions, all can give that hazy and dull look to your photographs. I've been able to work around a lot of it by manually adjusting contrast, gamma, and brightness in various software programs, but some of it just fights me no matter what I try. And I've had some otherwise pretty good shots unusable because of the darn old hazy look that I just couldn't get rid of.
Telephoto lenses make it worse. It's like looking through a cloudy aquarium at a fish - it looks o.k. when it swims right up to the glass. (Like a closeup photo.) But generally looks bad after it swims to the back of the tank. (Distance enhances the effect of the cloudiness.)
As with the water in an an aquarium , the more air the telephoto lens looks through (greater distance), and the greater the focal length, the duller and hazier looking the picture can become. Haze and soft contrast problems becomes significantly worse.
And because I'm a big telephoto photography fan, I run into the problem often.
I've tried polarizing filters on my lenses (some success), clear UV and other haze filters that are supposed to cut through and reduce haze (no success), lens shades, no shades, and assorted software haze-killers. (No good, no good, not much good...)
Then, one day while poking around Adobe PhotoShop, I started experimenting with "Auto Contrast".
Auto Contrast explained:
(The following explanation is copied verbatim from Adobe Magazine / May-June 2000 and explains the concept and mechanics of how it actually works it a lot better than I can.)
"... Auto Contrast automatically adjusts highlights and shadows to fix poor image contrast (so the results it produces will vary depending on the image). Auto Contrast is similar to the Brightness/Contrast command, which is a fast, easy way to adjust an image's tonal range while sacrificing some image detail. But Auto Contrast is designed to preserve image detail and also to complement the Auto Levels command, to create a more accurate tonal and color-correction workflow."
"Comparing Auto Contrast and Auto Levels may further clarify how Auto Contrast affects your images. Auto Levels corrects images with an overall color cast. To do this, it analyzes each channel individually and maps the pixels with the lowest values to 0 and the highest values to 255. The new Auto Contrast command, on the other hand, adjusts poor image contrast based on pixel luminosity, which it calculates based on a weighted average of the RGB values (remember, you asked!). It disregards the first 0.5 percent of the range of white and black pixels to ensure that it's getting representative image areas, and maps the lightest pixels in the clipped range to white and the darkest pixels to black. Highlights then look lighter and shadows darker, for finer overall image contrast."
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Here's how it works - Original 500mm telephoto image - Early morning light fog & sea mist create a hazy cast over the entire picture. |
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Select Auto Contrast from the pulldown menu at "Image / Adjust / Auto Contrast" |
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The
picture below is the result of the Auto
Contrast command - |
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Next,
go to "Levels". ("Image /
Adjust / Levels") The Levels control box and the results are shown in the next picture. It's almost like cleaning a dirty windshield, wiping a smoky film off window glass, or cleaning one's eyeglasses. And much like cleaning already clean glass, if a picture doesn't need it, Auto Contrast doesn't affect the appearance of a picture. A key thing that I've noticed is that when using Auto Contrast with a simple Levels correction, the color structure doesn't become disrupted, as it often is when using the Auto Levels command. |
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Then (personal recommendation) save your corrected picture as an RGB Tiff so you can fine tune it in a lossless format. At this point, I prefer using ThumbsPlus* to fine tune (tweak) the sharpness, gamma, saturation, and hue. Then, if you're a jpeg fan (as I am), save your finished product under a different or modified file name (remember, you have to change the file name so it won't overwrite the original picture.) *I've found that ThumbsPlus gives a much better screen view of a picture than PhotoShop does for final tweaking.
Here's the finished product - fresh, clean, and sparkly. |
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