Posts Tagged ‘Photoshop’

Thursday, October 2nd 2008

HDR – Getting it Right

Today I sat down and went about creating HDR images out of the multiple exposures I took on my last photo excursion. It was pretty tricky getting the settings right in Photoshop and it took a couple of hours of experimenting before I felt the output was what I wanted.

(If you just want the photos, scroll down.)

The main problem seems to be that when you press a large tonal range into 8 (24) bits of colour you easily end up with a very dull looking photo.

The fix for this dullness is using curves and local adaptation when converting from 32-bit to 8-bit. But, with endless possible combinations of settings it takes a while to find something that looks good and realistic.

I finally ended up with these settings:

  • Radius: 120 px
  • Treshold: 1.0

I also adjust the curve to only just clip the information in the 32-bit image:

Screenshot of the 16-bit conversion dialog in Photoshop with my favourite settings, radius 120 px and treshold 1.0

Those settings give me this:

A19070 - HDR

And for comparison, the original (metered exposure):

19070 - 2008-09-29 kl 17.46

I have put the best shots in a Flickr set.

Getting the shots right

While making the HDR images I realized that I didn’t take dark enough exposures to retain all the detail in the brightest highlights. I used the cameras auto-bracketing feature and did -2, 0 and +2 exposures, except for the last shot I took where I manually did -4 EV to +3 EV at 1 step intervals.

And it is only in that last shot that I can get all the detail around the sun.

So if you’re including the sun or a bright sky, you should probably go at least four stops below the metered exposure, and four above. If you follow Denny Tangs advice here that means that a series of -4, -2, 0, +2 and +4 should do the trick if you’re using an SLR.

If you use Photoshop for merging into HDR I’d love to hear what settings you tend to use.

Edit: Since posting I have decided to also add a very slight S-curve for slightly more contrast. The photos on Flickr have been updated.