ISO & Dynamic range - what is going on?

So, Donald, with all due respect:

THE ISO 15739 DEFINITION OF DYNAMIC RANGE
The concept of the definition
The concept behind the dynamic range definition given by ISO 15739 is based on the ratio of the saturation luminance to the lowest luminance for which the signal to noise ratio (SNR) is at least 1.0. This is based on the very arbitrary assumption that detail recorded with a SNR of 1.0 or above is useful and that recorded with an SNR less than 1.0 is not.

dougkerr.net/Pumpkin/articles/ISO_Dynamic_range.pdf

Let's say that an image has a saturation luminance of 4000 and the reference SNR is 1.0 at a luminance of 40. The ISO DR of that is 4000/40=100 or 6.64 EV.

Now apply your "noise filter". The SNR will still be 1.0 but now at a lower level of luminance than before, say 20. The ISO DR is now 4000/20=200 or 7.64 EV.

Ipso facto, QED, living proof that your noise filter increases ISO DR. Feel free to prove otherwise ...

D 😁 Dolby algorithm on a cassette deck 🤔they used frequency filters.

my daughter just tells me my english sucks 😊 , it is what it is 😊
I enjoy the banter btw ,just ask GB 😁

the whole point is that the larger pixels on the a7iv clearly beat the a7rv from my testing in my studio from the other week, i shot spiders with and the a7iv could capture the tones but the a7r5 clipped the silver consistantly all the time.

Entertaining as this all is, I can't help thinking that we've drifted a little here from a consistent topic...

I'm struggling with the concept of "near clipped". So red + white (pink), is not a valid skin tone because it sits close to the top of the chart?

Only happens on my computer if you try to read the second sRGB colour with the ProPhoto RGB profile, then it looks the same as the first.

😀

i havent gone off course at all as im talking about DR, can you give us a figure of how much DR is in the head shot based on the images i have posted ? or does DR increase or decrease with NR 🤔

Not from screenshots of parts of photos at 400%+ I can't. Nor can I do it from looking at tiny un-scaled histograms which only show colour distrobution post-conversion to your chosen colour profile. You're so far away from absolute data here with so many of the steps involving perceptual intents that I don't see how I can make any assessments of the absolute performance of the camera from the information posted.

For instance, RGB colour isn't real, it's how to create the "illusion" of colour to the average human eye. (Roughly) because we have three cones in our eyes all the real world colour is converted to three signals that our brain translates to "colour". Additive colour is simply using three carefully chosen bands of light to stimulate the cones in our eyes to produce the same signals as real colour does. The whole system is based on a perceptual intent, plus using three "absolute" bands of real world light puts real world limitations on the range of nerve impulses you can generate in the eye and the colour gamut that represents. So I have no idea where to even start to relate the RGB histogram of your chosen colour profile to the actual sensor data, or how I can see that by looking at the RGB output of a computer screen...

Well it seems to me that there is more than enough DR supplied by any digital camera made in the last 20 years that could have captured that image as it looks fine and is limited to the small DR of the container that you are displaying in it. As it is not a high DR image.

Here is a HDR image with 10-12 stops from full saturation

Hi,

Consistent topic. Pretty much doesn't exist in an online forum. There will usually be subtopics. Which are more easily followed or ignored when we have a Threaded View option. With that, following or ignoring subtopics is easily accomplished.

In this case, pretty much everything discussed so far is relevant. Except the part where someone thought transistors are always simply switches. And that has been sorted out. ;)

Stan

Who is also missing his signature line: Amateur Photographer, Professional Electronics Development Engineer

That question was answered here: dprevived.com/t/iso-dynamic-range-what-is-going-on/7370/post/104267/

Once again, DR increases with NR. Will you please stop asking how DR is affected by NR?

In terms of the ISO definition of DR, what is the Signal to Noise Ratio of the selected area? Say the green channels ...

[edit] for channel 4, it looks like SNR = about 3.4[/edit]

... or can you post that image please? ... or it would be nice to know the max raw level of the image?

but when i turn up incamera NR im not getting any more head room in the shadows or the lights 🫣the file is also smaller 🫣 why is this so 😁

Just as i have known for 50 years

Edit: Not a Direct Increase:
It's important to note that Dolby NR doesn't create a wider dynamic range than the original source material. Instead, it allows the recording medium (like a cassette tape) to capture a wider range of sounds than it could without NR. By compressing the signal during recording and then expanding it during playback, it effectively overcomes the limitations of the recording medium.
Impact on Sound:
If you play a Dolby NR-encoded tape without engaging the corresponding Dolby NR decoding (the expansion process), the sound will appear compressed and potentially muffled, especially in the high frequencies.

he posted the image on another thread

No link ... not found.

No further comment.

R- 16383
G-15778
B-16383
G2-15778

It was posted here but not the raw file
www.dpreview.com/forums/post/68279128

A quote from the same thread