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HDR Camera Raw Settings

December 17th, 2007


The image above is the pool house at Quarry Lake in Baltimore, MD. Click it for a better look. It was made by merging four bracketed images shot on a tripod at late dusk. I used Adobe’s system of merging HDR images which is a Bridge, ACR(Adobe Camera RAW), and Photoshop combination. The merging tips below are for photographers already somewhat familiar with shooting and merging HDR images. If you’re not familiar with HDR, Ben Wilmore has a really good HDR movie on XTrain; I also recommend The HDRI Handbook by Christian Block.

I use a number of different programs to merge image files into a single 32bit file. I choose which programs to use based on whether or not I need to batch process merges and whether or not I need to adjust the images before merging. Photoshop CS3 will not batch process merges and the file exposures needs to match the EXIF data. For batch merging and merging adjusted tiff files, I use Artizen HDR, FDR tools, or Photomatix. For example: I auto correct the RAW files using DXO Optics and output TIFF files, then I merge the corrected TIFFs in Photomatix.

Using the Adobe method is the most convenient way to get started. This is a script that Bridge runs, which invokes Photoshop’s Merge to HDR command. There are two settings inside Photoshop that affect the merge: (1) Align source images can be turned on or off. This is a real time saver if your images are already aligned and you don’t need a “perfect” merge. (2) Setting performance preferences to 0 history states in CS3 will also speed up merging.

Before merging images using Bridge I adjust my RAW files in ACR. Some ACR settings have no effect when merging. Most of the settings dealing with exposure make no difference. The merge to HDR function makes the image linear, which negates all exposure adjustments. Tone curve is the exception, as it does have an effect on saturation and color. Split toning has no effect. These are the settings in ACR that are important to the merge and should be adjusted:

  • White Balance
  • Clarity
  • Vibrance
  • Saturation
  • Sharpening
  • Noise Reduction
  • HSL
  • Chromatic Abberation
  • Defringe
  • Vignette
  • Camera Calibration

Exactly the same settings should be used on each image in the set. I’ve experimented with different settings in each image without much success. Photoshop crashes if the pixels don’t line up very well.

Once I have a 32bit image to work with, it’s time for some tone mapping, which is another blog in itself.

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  1. gilberto
    December 28th, 2007 at 23:04 | #1

    That Quarry composite photo is incredible. You just need to get the word out. If people know that you can do that fancy stuff, you will be kept busy forever

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