2010-10-14

Perfect HDR without a Tripod

Hi there! As usual, it has been too long and I cannot blame the studies for being too hard. Soon I'll be enjoying a 4 day weekend! Nice! But before that I would like to share a post-processing technique that will save a few bad HDR's (High Dynamic Range) in my collection (and hopefully a few in yours). If you are anything like me, you don't like running around with a tripod or maybe you just forget it at home. But then my brilliant brain (yes, sometimes it is brilliant) thought of a way to use Hugin, a free cross-platform program for making panoramas, to align multiple photos and re-save them as remapped images. Lets see a before and after at 100% crop and then start the tutorial!
100% crop of before and after alignment

First of all you will need Hugin (and maybe GIMP) and the photos that will make up your final HDR image. Here are three exposures that I have choosen for this tutorial:
Sample images for HDR

- Start Hugin and drag your images onto the window. It will automatically load the EXIF-information from the files.
- Go to the Images-tab and choose Align image stack instead of Autopano-SIFT-C (if you have autopano-SIFT-C installed you can go ahead to the next step) and click Create control points.
- When the control points have been created go back to the Assistant-tab and click Align.... This will align your images.
- Go to the Stitcher-tab and choose your projection. If you don't want any distortions choose Rectilinear and click the Calculate Field of View and the Calculate Optimal Size buttons. To be on the safe side, check you image by going to View>Preview window.
- If all looks good uncheck the Blended panorama under Normal output and check the Remapped images box under Exposure fusion. Click Stitch now! Choose where you want to save the images and wait for Hugin to save them. The image format will be TIFF.

(If your images have a weird projection you can specify the center of the image by left-clicking on where the center should be, and you can rotate by right-clicking at the edges of the image. But rotating is easiest done in GIMP)

If your remapped images have black or white borders, use GIMP to crop them before loading them into your HDR program. Now you are almost done. Here's my result:
Final HDR image (created with Essential HDR)

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