[Digikam-devel] [Bug 148382] overexposure indication already when fully "saturated"

[Dik Takken]

https://bugs.kde.org/show_bug.cgi?id=148382





--- Comment #17 from Dik Takken <d h j takken xs4all nl>  2010-01-05 08:54:56 ---
>When we are looking at HSV color interpretation we have Color, Saturation and
Value. Value (between 0.0 and 1.0) shows the lightness of a pixel, so I think
this is the one.

Clipping can happen to ANY channel, no matter what color space is used. The
saturation channel can also get clipped, leading to patches of uniform
saturation in the image. This is not as bad as clipping the Value channel, but
the pixel has been damaged. Period.

It all comes down to the same thing: When *ANY* value gets clipped, the image
has been damaged. Whenever this happens during editing, I want to know
immediately. And this is exactly what an exposure indicator is for.

IMHO, it's really quite simple. Clipping == Damage. Any code that does

     if (Pixel[Channel].Value > MAX) Pixel[Channel].Value = MAX

or

     if (Pixel[Channel]Value < MIN) Pixel[Channel].Value = MIN

has caused damage to the pixel. Therefore, it should indicate overexposure:

     if (Pixel[Channel].Value > MAX) 
     {
       Pixel[Channel].Value = MAX
       Pixel.Overexposed = TRUE
     }

     if (Pixel[Channel].Value < MIN) 
     {
       Pixel[Channel].Value = MIN
       Pixel.Overexposed = TRUE
     }

Yes, there are several different types of overexposure (luminance, saturation,
...). Personally, I don't care what kind of overexposure happened. Any kind of
damage is bad and should be indicated. Quite simple.

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