Does soft-proofing work without looking to the output profile?

[Elle (Elle Stone)]

@Hombre

But in RT apparently the output profile isn’t used as the source profile for soft proofing, which seems a bit odd but perhaps useful in the context of overall RT functioning.

Do not think that the developer of the softproof feature (i.e. me) is a master in color correction. That’s why I asked Marty Maria (developer of lcms2) to jump in our discussion in issue 3406. I’ll emphasis 2 things he said :

To implement proofing, lcms as most CMM does this chain:
Input image -> Input profile -> CIELab -> Proofed [printer] profile -> CMYK -> Proofed [printer] profile -> CIELab -> Monitor profile -> RGB

I’ve tried to ask the following question before, and maybe it was answered, so if it was already answered, my apologies!

In Marti’s chain of conversions, the first profile is the input image profile.

When soft proofing using RT, what is the input image profile? Some possibilities are:

1. Is the input image profile the camera input profile?

2. Is the input image profile the RGB working space that the user chose amongst the short list of allowed RGB working spaces (eg RT_Large, RT_sRGB, etc)?

3. Is the input image profile something else altogether, such as CIELAB, which would mean that RT immediately converts the interpolated raw file from the camera input profile to CIELAB for further processing? In which case what role does the RGB working space play?