I have a RAW file. Can I make different exposures with it to use in Photomaitx pro?

By Gavin  Jun, 03, 2011   Posted in FAQ on Photomatix

Yes, you can still use Photomatix when you have shot only one exposure in RAW mode. The big advantage, of course, is that you just need one image, so there is no need to use a tripod or to remember to auto-bracket, and it will also work if the subject is moving.
However, the range of “workable” exposures you can get from a RAW file is limited. If you are shooting a high contrast scene, you are unlikely to match the results you would have with taking the scene under different exposures that can cover the whole dynamic range.
There are three techniques for using Photomatix Pro with one single exposure taken in RAW mode:
· Technique 1: Open your RAW file in Photomatix Pro to tone map it directly.
· Technique 2: Convert your RAW file into a 16 bits/channel image in your favorite RAW converter, open it in Photomatix Pro, and tone map it.
· Technique 3: Create two or three exposures in your RAW converter and combine them in Photomatix Pro (or Photomatix Light) as it they were “real” bracketed shots
Technique # 3 often gives the best results. Also, it has the advantage of working with Exposure Fusion. Technique # 1 used to give less good results in Photomatix Pro version 3 and earlier, but this changed with Photomatix Pro version 4 and Photomatix Light version 2 thanks to the high-quality noise reduction algorithm implemented in the new versions.
To optimize the results achieved with a single-exposure capture, it is important to ensure the lowest noise level at capture time. For this, set the lowest ISO possible (ISO 100 for instance) and expose for the shadows when taking the RAW image, i.e. overexpose your shot. Even though the histogram of your camera may indicate that highlights will be lost, you should still be able to recover them during RAW conversion (unless the scene is too high contrast, but then a single image will not be sufficient for good results with Photomatix). There are two examples obtained this way here.
Deriving “fake” exposures from a single RAW file (technique 3 above) is theoretically an improper way of creating a 32-bit HDR image. If you intend to use the HDR image file for 3D rendering, then you should not use this technique, as you will not get accurate linear pixel values required for image based lighting. However, if you are only interested in the tone mapped result, then creating “fake” exposures is a valuable technique, as long as you get improved results over technique 1 or 2.
On the other hand, some high end cameras have sensors with a depth of 14 bits, which means two f-stops more of dynamic range. It is definitely a good idea to try the Tone Mapping tool of Photomatix Pro on the 16-bit TIFF file derived from the the RAW data of such cameras. Also, the dynamic range of the RAWs of the Fuji S3 and S5 Pro is higher than RAWs of other DSLRs.

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