P30 and 5D Dynamic Range

[Panopeeper]

That does not make any sense.  "Too few levels" can only increase the intensity of noise; it does not hide it.

When you have only three levels in a stop, you see "smooth" areas.

12 bits is all that is needed to convey all the signal and analog noise in current cameras, and that is needed only at the lowest ISO(s)

I just showed above, that the lack of reduction of the 16bit values to 12bit caused noise.

Note, that this does not contradict my other statement, that the lack of levels causes the 5D images appear less noisy; in the area I used in the demonstration there were still 8-12 levels per channel after the reduction.

You can't zero out the LSBs and expect to get good results. (and you *did* do it at the grey CFA stage of the RAW data, I hope).  You are clipping shadow detail by doing that, and darkening the overall intensity.  You must add 1/2 ADU of the resulting bit depth in the original one first.  In this case, you must add 8 before you integer-divide by 16

The effect of *maximum ONE* in the pixel value range of 1-4095 is negligable. Btw, who told you, that the value would be rounded if there were only 12 bits, instead of truncated?

The lack of black in your non-quantized +5EV P30 makes me think that there is some quirk in the processing.  The image looks too pale green.

After +5 EV only the "true blacks" appear black, and those are in other parts of the image (only some edges of the wooden doors on the kitchen island show massive blacks).

Re the color: 1. I did not make any WB, 2. there is no proper de-mosaicing, only an averaging of the colors. Sometimes I turn off even that, and then the image becomes very green, because half of all pixels are green (the true sharpness of the image can be seen that way).

[Ray]

This shot is clearly overexposed (the magenta indicates the lack of green, because I substituted the clipped pixels by null for this display).

And again: you have to add 1 EV in ACR to see the truth. I don't know, what caused this effect, but ACR treats every shot with the P30, what Marc posted, as in need for a -1 EV adjustment (thus you have to compensate with +1 EV in order to land at 0).
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However, if the only clipping of channels is in greyish clouds, then does it matter? Variation of grey scale values exist as one moves the eyedropper around the brightest areas. It's not as though the clouds appear as uniform white sheets of paper.

In a situation like this where one is striving to get detail in the shadows, insignificant technical clipping of grey clouds should not be an issue. The 1/15 sec exposure is the one I'd use for processing of this scene.

[Panopeeper]

In a situation like this where one is striving to get detail in the shadows, insignificant technical clipping of grey clouds should not be an issue. The 1/15 sec exposure is the one I'd use for processing of this scene.

It's a trade-off; if not everything fits, you got to decide, what to sacrifice. I often shoot with exposure bracketing and decide later, what is better.

Clipping is often limited to small or irrelevant areas, while underexposure can reduce the quality of large parts of the image.

The problem is, that the raw processors don't show the truth (that's what Rawnalyze is for). The clipping indication reflects the result after WB application and after exposure, brightness, contrast, saturation, curves adjustments. You can be led to believe, that there was clipping, while in fact no data is lost and by reducing the exposure (and adjusting the curves) you can get "back" everything (that's what the "recovery" function is doing). On the other hand, factual clipping can become "eliminated" by changing the adjustments.

[John Sheehy]

Gabor, I'd love to argue these things with you, but it is very difficult parsing your English.

When you have only three levels in a stop, you see "smooth" areas.

Not from a digital camera you don't.  None of them have low enough noise for that to ever happen to the RAW data with 12 bits.

I just showed above, that the lack of reduction of the 16bit values to 12bit caused noise.

That sentence does not make any sense to me.  I don't mean that I disagree; I mean that I have no idea what you're trying to say there.  What is "lack of reduction"?

Note, that this does not contradict my other statement, that the lack of levels causes the 5D images appear less noisy; in the area I used in the demonstration there were still 8-12 levels per channel after the reduction.
The effect of *maximum ONE* in the pixel value range of 1-4095 is negligable. Btw, who told you, that the value would be rounded if there were only 12 bits, instead of truncated?

Quantization always lowers the mean, if the bits being dropped have an equally distributed usage.

What is "maximum ONE"?

After +5 EV only the "true blacks" appear black, and those are in other parts of the image (only some edges of the wooden doors on the kitchen island show massive blacks).

Re the color: 1. I did not make any WB, 2. there is no proper de-mosaicing, only an averaging of the colors.[a href=\"index.php?act=findpost&pid=163981\"][{POST_SNAPBACK}][/a]

The main issue is *when* the quantization occurs; not the quality of the spatial color interpolation.

When do you do it?  I had the same problem with Roger Clark; he quantized a linear TIFF, already interpolated, and not properly offset, to argue against my claim.

If two people (or three people) quantize, and one loses nothing visible, that person can not possibly be wrong.  If there was anything to lose in the process, they would have lost it.  The people who lose something going to the same number of levels are obviously doing something wrong.