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

Started 2 months ago | Discussions thread
Mark Scott Abeln
Mark Scott Abeln Forum Pro • Posts: 14,344
You can't always get what you want

MrBrightSide wrote:

That's a deeper question. So which is more useful to the working photographer? I produce photos within an ecosystem in which I and my clients use Macintosh computers and Adobe software almost exclusively. There's a very predictable workflow in other words.

Arguably, it is typically only amateurs on a budget who worry about noise. The professional way is to avoid the problem altogether and not worry about it. Higher end commercial photographers and cinematographers throw huge amounts of light on their subjects, and buy or rent the best gear they can afford and use the largest format that is practical, and it has been that way for over a century.

The end result of this shooting is cleanliness which makes things easier for post-processing and editing.

So which would be more helpful for me in fine-tuning my exposure decisions? To know the effects on noise before going through the imaging chain or to know what happens after all the various programs have done their math?

If you shoot under ideal conditions, those with lots of light even if you use reasonable shutter speeds and apertures, then your work is easy: do you have clean shadow detail with a good exposure? The answer here is  either yes or no, and the reasons why may not be so important.

I think that it is valuable to know a little bit about basic imaging physics: that light has quantum properties that will introduce noise in all conditions, and how using good exposure will reduce the relative amount of noise. Also, having an idea of the amount of read noise that is introduced by a sensor helps considerably, especially if you want to use an antique digital camera for whatever reason. Also realizing how sensor size may influence the results can help also, as well as the trade-offs that switching sizes will require.

Getting deeper into the details is intellectually rewarding, and can be useful, but it does require lots of specialized knowledge and critical thinking skills as well as college-level math in many cases. Some details can be misleading: for example, much published noise data of cameras is only taken from the unprocessed green raw channels, but processing does change the noise characteristics which will vary with color and white balance.

And why jpegs? As we continue to converge video and stills, jpegs are becoming obsolete because they can't carry transparency information. Would the results be different with TIFFs and PNGs? Do they have different characteristics?

JPEGs have been adequate until lately. While it works well enough for final display, casual users these days are routinely doing strong edits on JPEGs (for example, "Instagram-style filters"}, and the bit depth is not quite good enough; also, higher bit depth, wider range monitors are becoming widespread. The HEIC/HEIF file format is gaining popularity as a replacement for JPEG: it supports more bits and transparency as well, and it is a video format as well (it is a container format, so it is flexible). As major vendors are supporting HEIC, it appears as though it has a good chance to be successful.

Bandwidth is still an issue: higher common data rates are being offset by higher resolution, and many web pages are littered with large numbers of images, while people are gaining an appreciation for high quality photography, so there is a need for good quality, high compression image formats.

TIFFs are usually huge, as they encode data which is not necessarily visible: particularly, high frequency detail and chroma information which typically isn't needed. Also, the bulk of TIFF data is false, interpolated data, at least with images that come from Bayer sensors. PNGs have some of the same faults, but its lossless compression works usually extremely well with line art and graphics.

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