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torger
2013-11-14 10:21:24 +01:00
parent 960254a8de
commit 017ee2de62
1 changed files with 37 additions and 12 deletions
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49
rtengine/camconst.json
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@@ -261,19 +261,44 @@ so you get output on the console (you need to start RT from a console to see
the output). When you load a file you will see a message of current black the output). When you load a file you will see a message of current black
and white levels and if they came from dcraw or camconst.json. If you're and white levels and if they came from dcraw or camconst.json. If you're
adjusting an existing camconst.json value you can just read what it is in adjusting an existing camconst.json value you can just read what it is in
the file and not need to enable verbose output. Reset exposure sliders to the file and not need to enable verbose output.
neutral, and zoom in on a large clipped highlight. Move around the mouse
pointer within, it should show stable 100% on R G B. If so, the white level Reset exposure sliders to neutral, and zoom in on a large clipped highlight.
is not too high, it could however be too low. To test that, go to the raw tab Move around the mouse pointer within, it should show stable 100% on R G B. If
and adjust the "whitepoint linear correction factor", reduce it until one of the so, the white level is not too high, it could however be too low. To test that,
channels is no longer 100%, and then increase in steps of 0.01 until all are 100 go to the raw tab and adjust the "whitepoint linear correction factor", reduce
again. Usually you play around in the range 0.90 to 0.99, ie a very small it until one of the channels is no longer 100%, and then increase in steps of
adjustment. Then divide the original white level with your adjustment to get a 0.01 until all are 100 again. Usually you play around in the range 0.90 to
new larger white level, which you then enter in your camconst.json file. The 0.99, ie a very small adjustment. When you've found this factor you should
same procedure can be used if the white level is too high, ie if you see pink apply it on the old white level to find a new larger one. As RT's "whitepoint
linear correction factor" work after blacklevel subtraction and camconst.json
want values without it we need to do some math:
BL = black level (typically something near 0, 256, 512 or 1024, find it in the
verbose output or if available in camconst.json)
F = whitepoint linear correction factor you just found out (typically in the
range 0.90 to 0.99 if you need to increase white level, 1.01 to 1.10 if
decrease)
oldWL = old white level, found in verbose output or in camconst.json if
available.
new white level = BL + (oldWL - BL) / F
Note that if black level is 0 which it is for many cameras, the formula
simplifies to: new white level = oldWL / F.
Here's an example from a Canon 1000D: black level is 256, old white level is
3651, whitepoint correction factor becomes 0.90, then new white level is
256 + (3651 - 256) / 0.9 = 4028.
If your camera have different black levels per channel use the smallest one
as that yields the most conservative result.
This new white level you then enter in your camconst.json file. The same
procedure can be used if the white level is too high, ie if you see pink
highlights, then increase the correction factor above 1.0 until you just start highlights, then increase the correction factor above 1.0 until you just start
seeing stable 100% on all channels, and then divide the original white level to seeing stable 100% on all channels, you use the same formula to calculate the
get a new smaller one. new smaller white level.
*/ */
{"camera_constants": [ {"camera_constants": [