Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
06-10-2010, 10:11 AM   #1
Veteran Member
Christopher M.W.T's Avatar

Join Date: Jun 2009
Location: Geelong, Victoria, Australia
Posts: 1,689
K-7 Hightlight Correction & Shadow Correction & Raw

Just wondering just enabling highlight correction and shadow correction affect RAW images or only just JPEGS?

I've gone through the manual and I can't find a clear answer on it.

06-10-2010, 10:33 AM   #2
Veteran Member
RBellavance's Avatar

Join Date: Nov 2006
Location: Near Montréal, Canada
Photos: Gallery
Posts: 1,716
The highlight correction affects the RAW in that it is effectively a "1-stop-underexposed-then-pushed" image. If your RAW converter does not recognize the relevant EXIF tags, the image will appears underexposed by 1 stop.

AFAIK, shadow compensation does not affect the RAW file, it is strictly a "curves" tweak done in-camera to produce the JPG.
06-10-2010, 10:55 AM   #3
Pentaxian
Lowell Goudge's Avatar

Join Date: Jan 2007
Location: Toronto
Photos: Gallery | Albums
Posts: 15,401
QuoteOriginally posted by RBellavance Quote
The highlight correction affects the RAW in that it is effectively a "1-stop-underexposed-then-pushed" image. If your RAW converter does not recognize the relevant EXIF tags, the image will appears underexposed by 1 stop.

AFAIK, shadow compensation does not affect the RAW file, it is strictly a "curves" tweak done in-camera to produce the JPG.
what I found is that as far as the correction is concerned on JPEG files, each function, highlight protect and shadow detail preserve, modify the JPEG as follows.

If you consider that JPEG with neutral contrast settings produces an image with average greyscale value at about 120, each full stop has a change of about 45 over the range 25-230

by using either function, shadow detail preserve, or highlight protect, the resulting jpeg has at least one full stop more, either below or above the mean value of 120, or both if they are both selected. the impact is a greatly reduced contrast.

as a comparison minimum contrast has 5 stops between 25 and 230 greyscale, maximum contrast has 4 stops. with shadow and highlight protection active, there are between 6 and 7 stops between 25 and 230 greyscale. at each end of the greyscale range the stops become quite nonlinear, but still their range is also expanded, giving 12-13 stops total detectable range compared to between 10 and 11 stops.

How do you test this?

set your camera to give correct exposure with any lens, such that you have at least 7 full stops of adjustment range to maximum shutter speed. then take shots at each shutter speed increment (ideally 1/3 stops) from maximum shutter speed to as low as you want (but ideally 7 stops or more below the "perfect exposure). The test subject should be a uniformly lit, single color surface.

when you have all the shots taken., measure the greyscale value of the histogram in a photo editor and plot greyscale vs shutter speed (log plot)
06-10-2010, 11:47 AM   #4
Veteran Member
kalison's Avatar

Join Date: May 2010
Location: Utah
Posts: 376
QuoteOriginally posted by RBellavance Quote
The highlight correction affects the RAW in that it is effectively a "1-stop-underexposed-then-pushed" image. If your RAW converter does not recognize the relevant EXIF tags, the image will appears underexposed by 1 stop.

AFAIK, shadow compensation does not affect the RAW file, it is strictly a "curves" tweak done in-camera to produce the JPG.
Learned this the hard way when I first got my K7. Luckily with RAW it's mostly correctable.

06-10-2010, 02:00 PM   #5
Senior Member
schmikey's Avatar

Join Date: Jun 2007
Location: Toronto, Ontario, Canada
Photos: Gallery
Posts: 159
I just purchased my K7 last week, upgrading from a k100D so there is lots to learn - but so far so good! I was just wondering the same thing a few days ago - there are new features that I am trying to get acquainted with. I shoot in RAW (now in DNG) is there a cheat sheet of features that I should ignore when shooting in RAW?
Thanks
Mike
06-10-2010, 02:26 PM   #6
Veteran Member
Christopher M.W.T's Avatar

Join Date: Jun 2009
Location: Geelong, Victoria, Australia
Posts: 1,689
Original Poster
Cool thanks for the responses.

The manual is quite vague on these functions, their uses, purposes etc.

Actually same goes for the image modes, Bright, Vibrant, etc

Do they influence the raw files in any way or is it JPEG only?
06-10-2010, 03:32 PM   #7
Pentaxian
Marc Sabatella's Avatar

Join Date: Sep 2006
Location: Denver, CO
Photos: Gallery
Posts: 10,686
The image mdoes are JPEG only. Only things that affect RAW are the parameters that affect the data recorded by the sensor, and thst's basically just the big three parameters that have been on cameras for over a century: aperture, shutter speed, and ISO. The highlight / shadow correction features are just fancy way of getitng the camera to deliberately shoot with the wrong exposure and then fiddling with the results in PP to look right. The RAw data will definitely reflect the wrong exposure. Whether or not you'll still see the image fiddle with to look right depends on whether the program you use to view that RAW data knows ho to reproduce the fiddling.
Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
camera, correction, dslr, photography, shadow, shadow correction
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
K7 & KX picture comparision take 2 (RAW & Jpegs available for download) Daemos Pentax DSLR Discussion 65 10-29-2009 11:13 PM
Pentax K-7 & K-X: My picture comparision (RAW & JPEG) Daemos Pentax DSLR Discussion 24 10-27-2009 09:18 PM
Highlight correction fulcrumx29 Pentax DSLR Discussion 2 08-16-2009 12:03 PM
RAW vs Manual White Balance for Color Cast Correction JCharles Pentax DSLR Discussion 18 11-09-2008 07:35 AM
Color Correction in Raw joreed3 Digital Processing, Software, and Printing 2 02-11-2008 09:39 AM



All times are GMT -7. The time now is 03:04 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top