Question about XYZ to XYZ with difference illumination and degree?

[diuming]

Is it possible to convert XYZ(D50 2°) to XYZ(D65 10°) by calculating?

[mm2]

I think, in general, it is not possible.

XYZ for a reflective source is the sum on all bands of spectral reflectance's x Spectral power distribution of illuminant x Color matching functions.

Color matching functions are empirical curves obtained from human observers. They differ in using an aperture of 2º or 10º to see the colors. Obtained curves are alike but not same.

So actually, if you have spectral data on the surface and the light, you can readily obtain XYZ on 2 and 10 degree as color matching functions are standard. But once you have the XYZ value, the spectral data is lost.

You could argue this is just a 3-> 3 correspondence and as such could be modelled by a look-up table, but it happens that 2 spectral distributions that are metameric (same XYZ) on 10º may yield different XYZ on 2º. So, I think it cannot be done at all.

[diuming]

Thanks, I got it.

My main purpose is to convert spectral tosRGB.
Currently! I only able to convert spectral to XYZ.
I also read some "Chromatic Adaptation" articles but I don't have any idea.

Another questions:
Is it correct path from Spectral to sRGB, Spectral(D50 2°) -> XYZ(D50 2°) -> XYZ(D65 2°) -> sRGB"?
Is it possible transfer with the same observer ? (like XYZ(D50 2°) <-> XYZ(D65 2°))
Could you give me some advice?