An interesting alternative to HDR

[bleirer]

Instead of HDR, average 4 or more shots of the same image. The article says every time you double the number of shots you reduce noise by 1 stop, increasing dynamic range by that same amount by opening up the shadows. Some pros and cons in the article. Your thoughts?

Averaged High Dynamic Range Technique (AHDR) Explained

A technique I recently learned allows you to capture lots of dynamic range in photography with better results and fewer downsides than traditional HDRs. I call it “AHDR” for “Averaged High Dynamic Range” photography.

photographylife.com

 

[RichF]

Interesting idea. In my simple understanding of S/N will be increased by averaging shots, so 4 sample average should reduce the noise by a stop (based upon sampling theory, poisson statistics). However other factors may come into play so not sure this is 100% correct.

 

[bleirer]

Interesting idea. In my simple understanding of S/N will be increased by averaging shots, so 4 sample average should reduce the noise by a stop (based upon sampling theory, poisson statistics). However other factors may come into play so not sure this is 100% correct.

That's pretty much what the article said in support of what you said. One thing it said was an advantage was ghosting would be less using the averaging. I guess with wildlife I'd envision several scenarios depending on how still the subject was. Maybe for a fast moving subject I'd envision some of the layers averaging the background and others concentrating on the subject, then compositing them.

 

[RichF]

That's pretty much what the article said in support of what you said. One thing it said was an advantage was ghosting would be less using the averaging. I guess with wildlife I'd envision several scenarios depending on how still the subject was. Maybe for a fast moving subject I'd envision some of the layers averaging the background and others concentrating on the subject, then compositing them.

All the gains require a sensor that is ISO invariant (from the little I understand from Steve's ebooks). The S/N gain is based upon creating a long exposure by averaging. This requires that there is no other source of noise in the system

 

[FB101]

The fast increasing number of shots needed to get more than 1 stop improvement says the return is fast diminishing beyond 4 shots. What you would gain in noise will be lost in sharpness due to minute alignment errors when dealing with large numbers of shots. His comparison to HDR is also flawed in the sense that he only gives an example with a +/- 1 stop bracket but you can of course do +/- 2 or 3 stop brackets giving a DR gain far beyond 2 stops and at both ends of the spectrum not just in the shadows.

so yes averaging shots has real value for small noise gains but in many cases it’s not an alternative to well done multi exposure and blending. Each technique has its uses. For those of us who remember scanning slides, you actually needed to do both - multi pass to reduce noise in the darker areas and multi exposure Because early scanners had terrible DR. Each addressed a different issue and same thing here. Averaging is great at reducing random noise but it won’t extend the DR past the limits of the sensor - HDR can capture scenes that have a DR beyond that of the sensor And when used in moderation can help with noise too. Horses nor courses as they say.

 

[RichF]

Wonder how pixel shifting on the Sony contributes to signal to noise? Not perfectly aligned, gain a some resolution, average surrounding pixels which are not precisely aligned. Lots of fine nuance points here. I suspect that different methods give different results depending upon the scene and camera settings.