Thursday, October 18, 2012

How to Fix Underexposure

In this post, we're going to talk about options for fixing intentional or unintentional underexposure.  This is for any camera, not just the Nikon D600.

We have talked about how to preserve highlights by underexposing the image.  See here and here.  The next step is to recover the midtones and shadows.  Here are a couple options.

FLASH
One option is to use flash at the time of the exposure.  In the shots below, my wife and kids were standing under a gazebo, facing the shaded interior.  I underexposed the ambient so that the sunlit background wouldn't blow out.



For comparison, here is a shot from the same conditions where I did not use flash and only used post-processing:

The advantage of using flash to bring up the exposure of the midtones and shadows is that the image quality will probably be higher because you'll have less noise and posterization.  The challenge with using flash is that it takes good technique and equipment to make it look natural.  (That will be the subject of another post.)  In this case, I bounced the flash against the canopy of the gazebo, above and slightly to camera right.

POSTPROCESSING
The other way to remedy the underexposure is of course postprocessing.  An easy way to do it in Lightroom  4 is to drag down the highlights while boosting the shadows.  Here is a sample.

This is the SOOC shot:

Here is the recovered shot, in this case with -100 highlights and  +100 shadows:

Super easy.  To me it looks ok, and this is the approach I used for a while.  However, it has somewhat of an artificial HDR look to it, which I don't like too much.  My current postprcessing approach is different.  It takes a few more steps but it is still easy (though not quite as easy as the above method).  Here is the result, side by side.


The new version looks much more natural.  In addition, when you look at the arms for example, they appear more three dimensional rather than flat.

HOW THIS POST GOT STARTED
Before I talk about my new approach, you may be curious about how the new approach originated.  You know what?  It directly originated from a comment on this post, from Mark.  Mark observed that some of my shots look HDR-ish.  Mark's comment gave me the impetus to work on that issue.  And now look what resulted.  Isn't that amazing, how much a short comment had a significant impact?

This is by no means a unique example.  I can cite many others.  Here are a few:
- A long time ago, a reader suggested using Neil's black foamie thing.  Here is the resulting post.  You also know how often I have recommended Neil's BFT since then.  And you might recognize that reader now. :)
- I got introduced to wide angle lenses because of a comment by Opt on this post.  The Tokina 11-16 and 10-17 are now two of the lenses I most often use.
- A photographer asked me how to apply the D3200 camera profile for the D600.  This is the resulting post.
- A reader emailed me to analyze some images that he liked and I found how focus stacking could be used in a non-macro context.  (Subject of a future post.)
I really could go on and on.  What I hope you get out of this is that YOU are important.  On this blog, your involvement matters to us and has a significant impact on the blog and its readers.  Why?  In no small part because I know there are readers who are more talented, knowledgeable, and experienced than me.  So I listen carefully.

And I am very grateful to all of you who have taken the step of getting involved.  By that I mean anything from even posting a comment (even a criticism), sharing a link to this site on social networking sites or another forum, or emailing suggestions and questions.  And you know what?  There are tons of other ways to get involved.  Maybe you have a lens or equipment that you'd like to review.  Maybe you have a photo-related site and could mention us.  Maybe you are a web designer and know how to improve our site's layout.  Maybe you're a marketing or SEO guy (I'm clueless about promoting our blog).  Maybe you can help us update our index.  Got a huuuuuge backlog of article ideas too.

For some of us getting involved is second nature.  But for some of us it is not.  So, what's in it for you besides being able to help other readers?  Consider this - the most successful photogarphers I know are connected.  To other photographers, their audience, their community, and especially to their subject.  (And actually, it's not just photographers, it's virtually anyone successful I can think of.)  So getting involved is you getting connected.  Consider the impact that being connected may have on your photography and your life.  What would that look like?

Yeah so that's my take on how to fix underexposure. :)

BACK TO OUR REGULAR PROGRAMMING
So, let's talk about the new process I'm using.  Here are the things I do in Lightroom 4.  (BTW, in LR, the order in which you do them doesn't matter.)
1. Highlights: -100 (or as much as needed to get all available the highlight details)
2. Using a local adjustment brush I paint an additional -100 Highlight.  Usually I do this on the whole image with a large brush.  Related post.
3. I decrease contrast.  You'll see that the shadows will get lifted a bit while the highlight details become easier to see.  Depending on the contrast in the scene, I decrease the contrast up to -67 or so.  More than that and the image starts to look weird.
4. I boost shadows only up to +20.  More than that and the image starts to look HDR
5. I increase the exposure.  In LR4 this will affect the midtones more than the highlights.
6. I deepen the blacks by adjusting the black clipping slider.  By how much depends on the image but usually I want a pure black on a small part of the image.
7. If there's a little space left on the histogram between the highlights and the peak white values, I increase white.

Here are more shots that were post-processed with this technique.



All shots were with the Nikon D90 and Nikkor 24-70.  (I might post the SOOC versions but they look pretty much like silhouettes.)  BTW the Nikkor 24-70 was not such a bad focal length for the APS-C D90.  At its widest it was still reasonably wide.  At its longest it was a portrait-like lens.  Focus was off on some of the shots especially the backlit ones.  The D90 seems to struggle under those conditions.