histograms and DPP

[Marquinius]

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Where does the jpeg conversion routines enters the histograms?

I thought histograms are direct representations after reading sensor signals.

 

No, I've also read that the histogram on the back of your camera is an aproximation, based on the Jpeg. It's OK-ish, but the raw will have more info: you could see a clipped histogram on your M8, but in DPP you'd see that there's still info. As they wrote ...

 

I wouldn't bet on it though ... I'll go for "slightly right sided" ...

 

 

ahhhh .. from a simple test to this info ... not half bad ...

 

Marco

[sandymc]

Sandy, when you say curves, you refer to the LUT?

I would say that using 1250 or 2500 ISO means more gain, and that introduces noise no matter what.

 

Curves as in, e.g., Capture's One's "Film Standard" setting, which increases contrast in the mid tones.

 

Higher ISO (mostly) doesn't actually have more noise; the noise level is pretty much fixed by the sensor. All you're seeing is the same noise amplified up. So, in principle, whether you amplify in camera with the ISO setting, or in post processing shouldn't make a difference. However, the difference between "in principle" and "in practice" is whether all the information form the sensor gets to the raw file. And for the M8 (and to lesser extent pretty much every camera, because of various real-world imperfections in the sensor chain) reality is that you maximize the amount of information in the raw file by "exposing to the right". The M8 is an extreme example of this because of the 8-bit compression.

 

Sandy

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[FMB]

I’m trying to arrive to several conclusions:

 

1- Histogram is only a good guide.

2- Actually we don`t know if, talking about M8, the histogram is a representation from the elaborated jpeg file or only the “raw” luminosity captured by the sensor. (We should ask Leica people because it seems to me it’s very important to know which is the true fountain of the curve).

3- Noise is there. One must expose not only according to the histogram but to a personal evaluation of the darkness, contrast, softness, etc. of the subject.

4- We should not abuse no more than 1-11/2 stops.

 

Francisco

[diogenis]

Yes- histograms are helping assessing your pics fast eliminating mistakes irrevocable just before you leave the scene.

I would say that histograms are sampling directly data from their sensors. Meaning RAW data. There is no need to involve elaborate jpeg procedures and stall the camera.

Obviously, you got some 10Mp of data to show on just a small 2" screen, but it's still a good indication.

ISO=gain, which grossly is just a multiplier, therefore it will amplify whatever noise the sensor creates.