Saturday, August 13, 2011

Tweeking a Hand Held HDR Image

Taming the Two-Headed Monster

Sometimes even the best HDR processing software just can't prevent something weird from appearing in the picture.

I was photographing the Memorial Bridge in Portsmouth, NH, which was recently closed to vehicular traffic.    The bridge closing was the result of nearly a century of structural decay, and the state of NH decided to give up on the bridge rather than try to repair it. The closure gave me the opportunity to get some shots that would have put me in the line of fire if cars were still speeding by.

The sky was overcast but bright, the details were stark, and the shadows were deep.  The setting begged for HDR imaging.  Here's one of the images that resulted from the shoot, processed in Nik HDR Efex Pro using three bracketed images shot while holding the camera in my hands.

To enlarge this, and all images in the posting, click on the picture.
The HDR processing toned down the sky a bit and effectively brought out the details and texture in the iron work.  However, the worker in the top right corner of the picture did not cooperate by holding still.  Here's a detail of that corner of the image:

The processing software couldn't decide what to do with the multiple images of the worker, so it incorporated them into the picture, producing a two-headed artifact.

Sometimes, Topaz Adjust produces an image from one exposure that is just as effective as a multi-exposure HDR image.  So I put one of the three bracketed shots through Topaz Adjust to eliminate the artifact of the two-headed man.

Here's the full Topaz Adjust image:

And here's the detail of the bridge-worker:

The bridge-worker is fixed, and Topaz makes him look great. But the detail and texture produced by Topaz Adjust don't equal what I like about the HDR image. 

Ideally, I'd be able to combine the HDR image with the top right corner of the Topaz Adjust image.  Fortunately, this is easily done in Photoshop.

Here's the result:

This is how I did it:
1. I opened both images in Photoshop.  I use Photoshop CS3. 
2. I created a two-layered image, overlaying the corrected detail on top of the other.  I entirely masked out the image that has the detail I wanted to correct.
3. With the brush set to white, I revealed the detail I wanted to place over the faulty image.

Layers are wonderful!

Trey Ratcliff fully describes this technique in his book,  A World in HDR.

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