Posterized red

Not if you're doing the editing properly.

And that's where I've seen most posterization - in the color transform from the large spectral response of the camera to the limited gamut of display media. I mean, it's all just an approximation of the rich hue gradations we actually see in the scene. Working in floating point by itself doesn't make the transform work any better if it's just matrix-based, which deposits the rich colors just inside the destination gamut without any regard to their original gradation.

That's the key thing to remember looking at any picture - you're looking at an approximation of the original scene color, based on the limited capabilities of the rendition medium.

I'm afraid we are mixing things here.

A colour transform is one thing, a camera is another, and the scene in nature is the third.

Posterization is just another form of visible artifacts. Not like noise, it doesn't take much to avoid posterization, bland clusters and bands, devoid of detail in colour and luminosity, by using eyedropper, magic wand, and watching gamut and histograms.

The quest for "Zero Noise" is a horrible target, for 8-bit displays.

Do you think I'm suggesting zero noise as a goal? Or are you in agreement with what I said, and are talking about how to do proper editing? If the latter, I agree. And it's not a good target for inkjet printing. In fact, blue noise is usually added during the error diffusion halftoning for inkjet printers.

No.

Apologies, you brought up renditions, I thought it would be helpful to recognize one source of the introduction of posterization.

It depends on the definition of "editing properly".

Is it not feasible that editing to prevent posterization might not allow the desired final image to be produced?

In any case the rest of my sentence you quoted was

If the posterization is not noticeable or objectionable in the final image/print then it really doesn't matter.

If the idea for the final image doesn't include detracting posterization, properly edited image will have none.

I think not, with modern cameras. Show me an editing sequence that is necessary to produce some desired image that must create posterization.

That is my point.

It doesn't matter to me if my final image has posterization as long as it is not noticeable or objectionable.

But isn't posterization sometimes introduced when going from say 16 bits to 8 bits and so is not a result of any actual editing?

In that case trying to edit out the posterization in the 8 bit version might result in an image not exactly as initially desired.

It isn't if the editing sequence is controlled.

If I understand you correctly, are you saying that if there is no posterization in a 16 bit image then it is impossible for posterization to be introduced into the image after it is converted to 8 bits?

The choice of output format is an editing decision.

He didn't say it was impossible. It is possible, but it can be avoided.

I am not aware of any options during a 16 bit to 8 bit conversion in any app that will guarantee no posterization in the 8 bit version if there was no posterization in the 16 bit version.

Can you suggest an app and the options/settings within it if an app exists?

You can edit the image to avoid areas that are problematical for posterization given the output color space and the image. Or you can apply dithering in the 16-bit precision space before conversion. Ps has ways to generate dither. But if not further editing is to be done on the 8-bit image and you avoid wide gamut spaces like CIElab and PPGRB, posterization is unlikely if the editing is performed in the 16-bit space.