Issue at ISO400+ with my dcraw-patch for Nikon Coolpix P7000

As I wrote earlier I patched dcraw to work with my Nikon Coolpix P7000. However, there seems to be some problems at ISO400 and above.

I made the same shot twice from a tripod, with the same settings (f/4.0, 1/30s). In the first case I used ISO100 and flash=1/4. In the second shot I used ISO400 and flash=1/16.

How to read it:

  • to the left: ISO100, developed from dcraw
  • to the right: ISO400, developed from dcraw
  • middle column: JPG from the camera ; if you look closely ISO100 in the left half and ISO400 in the right part
  • top row: dcraw with no processing switches activated
  • bottom row: dcraw called with -W, will not auto-bright the picture

So, after first concluding that brightness is tricky (but can be fixed/adjusted with the -b switch), lets look in the right column at those ISO400 pictures. Obviously they are too pink, and they also have a kind of foggy layer over them (I think).

Now, dcraw has a switch for “darkness” (-k). Have a look at the pictures below. I shot six raw pictures at ISO 100, 200, 400, 800, 1600 and 3200 (from top to bottom). I developed each picture four times with dcraw at darkness values 0, 128, 256 and 512 (from left to right).

As I see it, the right darkness value depends on the ISO value as in:

  ISO   Darkness
  100   0
  200   0
  400   256
  800   256
 1600   256
 3200   256

I need to think about an elegant patch for dcraw.
My patch for dcraw now fixes this problem as well.

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