Here's how to read the SNR from DxO:

1) Go to Full SNR graph, e.g.

http://www.dxomark.com/Cameras/Canon/EOS-5D-Mark-III#measuretabs-62) Choose a reference level (say 18%) and read the SNR (in this example, 39.7 dB)

3) Remember the modified ISOs will let you expose a little more to the right, let's say by 0.4 stops. That means, your reference level on DxO graph will now be 18 * 2^0.4 = 23.75. Note that in your image, the reference level will be still 18% relative to your new white point (but this new white point just got higher than Canon default with 0.4 stops). New SNR: 40.9 dB.

4) SNR improvement at 18% level will be 1.2 dB = 0.2 stops

*if you shift the exposure to the right* (so you keep the same amount of highlight detail). If you keep the same shutter speed and aperture, same scene, and develop at the same brightness in post,

*noise will not change* (except for maybe some round-off errors).

So, the improvement in midtones is pretty small, but these midtones have little noise to begin with.

And here's a module that does a *rough* estimation of the SNR curve from a defocused image, and also computes the dynamic range:

**raw_diag.mo** (source:

raw_diag.c)

The module does 3 types of analysis:

- optical black (it draws the noise histograms as the ones I've posted earlier in this thread)

- dark frame (same, but analyzes the entire image - very slow)

- SNR curve (take a defocused picture and it plots an approximation of SNR as a function of signal level)

I'd like you to run some tests with the raw_diag module and check the repeatability of the measurements (maybe compare it with DxO, RawDigger or whatever, or just review the math). For dynamic range, make sure you have something overexposed in the frame (e.g. point the camera to a light bulb). You may also post tables with dynamic range at each ISO from your camera (which should be comparable, since they will be computed with the same algorithm).