Sunday 7 April 2019

How can I get a good HDR image from a single RAW file?


I've heard that it's possible to create an HDR image from a single RAW file. (Obviously, it won't be as good as using multiple bracketed RAW files; I know that much.)


Every time I try — using Photomatix with the default settings -- the results are truly awful. I'm not even trying for something printable, I mean it's too noisy, blotchy and generally horrible even for viewing onscreen.


Does anyone have any tips — either about what kind of RAW files will work well, or about how to tweak the Photomatix settings for this case, or about other software which will do this better?




Answer



Ideally you want to capture at least 3 distinct images, but the more properly exposed your single raw image is, the better the outcome.


By proper exposure (a subjective term), I mean to expose to the right. You want to capture as much detail in the shadow areas of your image, without blowing out the highlights. The way dSLR CMOS sensors work, they do a much better job capturing information in an image that is slightly overexposed, than with an image that is underexposed (shadow areas will have more noise).


When you have your single RAW file, you want to hopefully create at least three images with varying exposure levels. Depending on your base image, these exposures may be -2/0/+2 EV or -1/0/+1 EV (as Marc's answer (and image shows)), or some variation of three exposure values--one that is less than your base image, and one that is more than your base image. You will need to play with the EV values until you get the intuition on what EV values will work with your base image.


When using Photomatix, try playing with the settings, the default values were never good. IIRC, bumping up the strength to full, and then tweaking from there produced good results.


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