Custom Curves - Canon CHDK Quick Start Manual

20

Custom Curves

Enables the use of custom "curve" profiles to adjust the exposure of
your RAW and JPG images. (Cameras with 12 bit sensors are not yet
supported-
Dec09
Difference between CV and CVF curves:
CV curves are the standard RGB curves.
CVF curves are special versions of the curves which intends to
avoid color shift side effect of the RGB curves. They are an
approximation of the luminance curves.
Except the SYSCURVES.CVF file it is recommended to put the curves files in the
\curves directory.
See:-
http://chdk.setepontos.com/index.php/topic,932.0.html
Enable Curve
• None - No curve profile is applied.
• Custom - Your custom curve profile is applied as-is.
The following three options require that you have a SYSCURVES.CVF file in your /CHDK
folder, this file is included in the "complete" CHDK packages. It is also contained in a file at
http://chdk.setepontos.com/index.php?action=dlattach;topic=932.0;attach=1816
contains the editor.
Due to the limitation to short 8.3 file names in the file browser of current DryOS-based
cameras the file "SYSCURVES.CVF" should be placed on the memory card by a card reader;
in the CHDK file browser the file name is shown in shortened format as "SYSCUR~1.CVF".
• +1EV - Increases shadow detail by
• +2EV - Increases shadow detail by
• Auto DR (auto dynamic range):
Auto DR with Zebra is intended to be used for the direct application of the curves to the shot
- and not for post processing (the feature is just mimic of the Fuji S100 +200, +400 Dynamic
Range). The flow is:
1. - Activate Zebra display
2. - Activate Auto DR
3. Use the camera EV negative compensation to reduce the Zebra overblown highlights
shown on screen. You can use the (+/-) button on the back of the camera.
4. Take the shot. You will directly get the JPG without post processing. The luminance of the
darker areas will be raised while the highlight is compressed.
During the RAW develop process, you need to set the EV comp. to the value that you used to
reduce the highlight blown out when you took the RAW. Care should be taken with in camera
develop since it is a tricky art there (for White Balance issues in particular).
If the scene does not require you to reduce exposure to avoid blown highlights, the Auto DR
feature does not do anything.
Load Curve Profile
Load your choice of curve profile from your \CHDK\CURVES folder. All curve profile files
except for
SYSCURVES.CVF
See also:- Curves
< Main Menu
).
[ None, Custom, +1EV, +2Ev, Auto DR]
should be in this folder.
on page 54.
1EV
step.
2EV steps.
which also