To correct the initial color balance and remove the orange mask of a scanned color negative we would normally set black and white levels to just barely clip each color channel. This works fine with shots that have both black and white points in them like those having, for example, a deep shadow under a tree and a blown highlight like a glare or a light source.
But how to correct the color and exposure of a negative that lacks either one of the points or both of them? The goal is to preserve the exposure, contrast and color characteristics of the original film shot without corrections.
Examples of the shots:
- a sunset shot with the black shadows on the foreground and the orange colored Sun disk being brightest point of the frame - no white point in the shot
- a shot of water surface with light reflections and no deep shadow details - no black point in the shot
- a shot of a misty landscape on a heavy overcast day - neither black, nor white point in the shot
We could of course color-correct the images by feel, rely on the memory of the actual scene or use common objects for color reference, but here we want to preserve the lighting effects or color casts captured on a particular film stock that were present in the actual scene without any artistic intrusion. The same is true for the shots we have not seen in person.
Any artistic intrusion could be performed after the initial scan corrections, is optional and is out of the scope of the question.