Thursday, March 8, 2012

Saving an overexposed HDR - Rosenborg Castle

This article presents a nice finding about using Photomatix. The subject is an image of Rosenborg castle in Copenhagen, during the sunset. Three exposures (-2, 0, 2) has been taken hand-held, the middle one being a bit overexposed due to shooting against the sun (+1 exposure compensation).

originale
Original files

The target is to get a rich tonal colour range and recover the overexposed sky. Ideally using the tripod you can go one exposure down (-4), but being hand-held, you cannot do this.
For this tests I used Adobe Camera Raw conversion for RAW to TIFF conversion (as many other resources on the internet states, a dedicated RAW conversion is better then the Photomatix one). No noise reduction or other processing has been done in this step (for the simplicity of the test). I used exactly the same saved custom pre-set in Photomatix.
A) Feed Photomatix with the -2, 0 and 2 tiff exposures.
B) Produce extra -1 exposure by reducing the exposure of the original 0 RAW file and +1 exposure by reducing the exposure of the original +2 RAW file. Feed -2, -1, 0, 1, 2 into Photomatix.
C) Produce extra -4 exposure by reducing the exposure of the original -2 RAW file. Feed -4, -2, 0, 2 into Photomatix
D) Produce extra -4 and -6 exposures by reducing the exposure of the original -2 RAW file. Feed -6, -4, -2, 0, 2 into Photomatix

These are the results after Photomatix:

Tonemapped in Photomatix
Tonemapped in Photomatix

Conclusions:
A) and B) looks very similar colour wise. The sky is unfortunately blown out due to direct shooting in the sun. The details of the castle are looking fine and the colours seem natural.
C) is looking pretty good. More orange colour specific to sunset, better colour in the water reflection of the sun, unchanged colours for the castle and the grass area under it. The sky colour look more bluish.
D) is way too saturated in the sky. It could be corrected in Photoshop by masking the area and desaturating it.

Verdict: without a doubt I select C) as the clear winner. A simple additional step of producing -4 exposure artificially in Adobe Camera Raw can save the day.

If you were wondering how the final image looks like, here you go:

Rosenborg Castle

1 comment:

  1. Thanks for this quick test. This and next week I have a lot of work shooting interiors. I will use some of the time shooting extra HDR photos and try the system "C".

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