The Making and Use of Camera Curve Profiles

(= Poor Man's RAW II)

 

We start with the creation of the HDR-image of the moon based upon the four different exposures as shown on the previous pages. In the illustration below, the four images have been opened in PhotoImpact and we have entered the HDR-menu:
 

 
The HDR-image as such (Picture I. on the previous page) will be generated by pushing the "create-button" at position X in the illustration above. However, to me the really intriguing thing is the possibility to generate a camera curve profile for my particular camera and type of scene. It is as simple as this (ref. positions marked A., B. and X. in the illustration):
 
    
To generate a camera curve profile (in PhotoImpact):

1)Apply the radiobutton, "Autogenerate camera curve".

2) Press "save as"

 
3) Apply a unique name (here: MyLunarProfile1) for your personal camera curve profile and press "save"

4) Press "Click this button to create a High Dynamic Range image" (at position X. above) and you are done! Now, you have not only the HDR-image but you also have your own, specific camera curve profile (in PhotoImpact labelled CCF-file) for later re-use on single-shot exposures of similar type.

 
To see haow well this works, let us take the darkest lunar shot, (image H. on the previous page) used to generate my CCF-file above. Open it in PhotoImpact and  go to "Photo" - "Light" - "SmartCurves". In "SmartCurves" you will now find your personal CCF-file; pick that one for processing as shown in the screen-dump below:
 

 
-----and here is the result:
 
 

Original image: 1/180 sec. exposure at f/10

 

Enhanced image using "MyLunarProfile1" generated above.

 

Note that not only has detail in the dark parts been greatly enhanced but also that the enhanced image - produced using just a single shot - has a remarkable resemblance to the HDR image on the previous page (image I.), which was produced using four different shots. This again stresses the fact that whereas overexposed images cannot be salvaged to any reasonable degree - if at all - underexposed pictures often contains much more information than meets the eye at first glance. And, if it has been recorded by the CCD, it can also be brought forward for the eye to see.

 
As I indicated on the previous page, curves generated as here described may also be used for similar, but not necessarily "identical" scenes. As an example, let us try out the curve on a shot of the sky with a single bright star (Arcturus) and a few clouds:
 
 

Original image: 6 sec. exposure at f/2.8 and ISO 400

 

Orinal subtracted dark frame (to eliminate "hot pixels" and enhanced in PhotoImpact using "MyLunarProfile1 generated above.

Click on thumbnails to see large images

 
Clearly, curves and camera curve profiles are very efficient tools if you want to get the most out of your digital images!
 
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Copyright 2009 - Steen G. Bruun