Difference between cameras (raw)?

[bastibe (Bastian Bechtold)]

@ggbutcher

I’m going to give you a different way to start your thinking, and I think it ends up in the same place, you can make the output of different cameras look approximately the same in tone and color, although I’d need a few more-different cameras to work through it.

Hardware-wise, the product of digital image capture is a set of measurements of light intensity, taken through different bandpass filters organized into the mosaic. Plotting that data across the spectrum wavelengths looks like this:

Just utterly fascinating! I must have subconsciously had your posts in mind when I started thinking about this issue yesterday. I think my question indeed boils down to sort of the interpretation of your response curves: what does it mean that the response curves are different? How do these differences manifest photographically?

I think both the theory and my haphazard measurements bear that it doesn’t mean a lot in terms of lightness response at least. But if I understand the math correctly, color response should be at least somewhat affected, right? There should be some remnants of differences that can’t be compensated bu color space transformations, I think.

@ggbutcher

To continue my line of thinking, I first lamented I didn’t have more cameras to show, then realized I did, in the camspec SSF database. It’s essentially a text file of SSFs for 10 cameras, monochrome-measured by Christian Mauer in conjunction with his university thesis. I posted a page of their plots here:

Thank you for these additional resources!

@Jossie

I do not think this is correct in view of what I described above. As Glenn has described the sensitivity curves differ from manufacturer to manufacturer. Colour transformations can then bring the colours to a desired colour space, but not always identical and successful (see above comparison with sRGB).

I think I don’t understand your sRGB plots. Where did you get that sRGB from? My cameras do not produce sRGB raw files, but something with a markedly larger gamut. And as @ggbutcher showed, color primaries of different cameras are at the very least different, and therefore can’t all be a representation of sRGB, right? Or am I fundamentally misunderstanding something?

Please don’t take my words as criticism; I am genuinely curious in what your sRBG graphs are showing, and what this means photographically and in terms of signal processing.