How Do I Measure Noise Using Photoshop? And What Is A Significant Change?

Started 2 months ago | Discussions thread
OP MrBrightSide Contributing Member • Posts: 747
Re: Measurement is futile

"discussions about noise with colors is usually highly anecdotal and surprisingly little hard data is commonly available"

And yet, the hard data is out there being generated by scores of dedicated and talented people around the globe, so I have to ask why serious academic or professional findings are so rarely reported or discussed at the most important website in the photography world?

With so many distinguished members of the Science forum, we should be awash in significant findings from real scientists, yet as you point out, we're not. Is the problem that no one can afford the extortionate prices charged by the greedy academic publishers?

In the interim, I have chosen to hack my own path through the tangle of Wikipedia "facts" and self-recursive theories that seem to be society's preferred alternative to actual thinking.

Mark Scott Abeln wrote:

MrBrightSide wrote:

That’s deep. Are you saying that trying to measure noise is futile?

What is futile is trying to measure noise in a JPEG or TIFF, where at a minimum, the noise characteristics would change with color, camera profile, white balance, etc. It would be difficult to get good results unless you are quite systematic: also, the results may be misleading.

Shooting a ColorChecker target under varying but consistent conditions could be useful, but only as long as you are systematic.

A synthetic approach, where you start with basic raw noise measurements and then estimate the final image noise characteristics—after raw conversion—can be quite informative. The measurement phase is rather easier, as you only measure grayscale values, but you need to figure out what calculations are needed to get a full color image (there is some published data): and from this, it’s fairly easy to get color noise estimates, which can be compared against actual images. Any great discrepancies can then be analyzed.

Published noise figures for sensors typically only consider these raw measurements, and then only for the green channel. Discussions about noise with colors is usually highly anecdotal and surprisingly little hard data is commonly available; unfortunately it varies with processing and shooting conditions, ensuring unresolved arguments for years to come.

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