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Noise reduction: Overexpose, underdevelop     posted on 19th of september, 2007

Have you heard this formula? If you first camera was Kodak Instamatic you probably have. If you first camera was digital you probably haven't.

Overexpose, underdevelop is an older (though still widely used in practice) way of shooting. In short it means that one should give more exposure to film then it should be for given ISO and luminance of the scene. What the overexposure gives us is detail preservation in shadows. Isn't it great?! Well, not exactly. Because overexposure blows out highlights. To preserve highlights one needs to underdevelop. Thus this approach allows better detail preservation/grain reduction in shadows. You may dig Internet for better details why it happens. In shot, the approach uses non-linearity of sensitivity curve of film and developing process.

Can it be used ...

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Tags: exposure noise reduction technique

Comments (5)

Thank you. I'm glad to be at help - posted by Actionwatcher on September 20, 2007
Interesting read. Thank you. - posted by Sebcz on September 20, 2007
Excellent questions. Regarding combining differently exposed images: The shot answer will "No". If light allows overexposure one overexposed image will most likely take care of both noise and shadow details with much less work on your side. The long answer will be "Yes". Is it funny :). If you would like to achieve higher level of noise reduction or there is no much space to the right to overexpose then two frames would helpful. Moreover, there is a lot of cases when light is too harsh thus shadows are blocking (too dark) and highlights tends to blow out. In such cases combination of two or more differently exposed images will solve the problem of shadows and highlight detail preservation. This technique can be called either HDR or extended dynamic range. Photoshop CS2 and CS3 and also number of other software applications will be at great help. Unfortunately, if the dynamic range is too high then the final image may look unnatural and generally will require a lot of work and experience ... More) - posted by Actionwatcher on September 19, 2007

Comments (5)

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