IT8 calibration for SilverFast HDR

All about SilverFast HDR and HiRepp (48bit HDR processing)

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LSI_Ketelhohn
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Re: IT8 calibration for SilverFast HDR

Postby LSI_Ketelhohn » Tue Jun 05, 2012 4:29 pm

Dear customer,

SilverFast HDR does not need to be calibrated.
This is only necessary for hardware components.
SilverFast HDR can be used to create ICC profiles for digital cameras by taking an image of a special target and then loading that image into HDR and using the calibration there.
But that is also a hardware calibration and not the software itself which is calibrated.


kind regards,
Arne Ketelhohn.

EricLawrie
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Re: IT8 calibration for SilverFast HDR

Postby EricLawrie » Tue Jun 05, 2012 5:16 pm

Thanks for getting back. So if HDR does not need IT8 calibration, what then is used as a profile under INPUT within the the CMS preferences? In Ai Studio I used either if the two the IT8 profiles I generated for 35mm transparency scans specific to Fuji Velvia or Kodachrome. But what do I put here if I am using HDR?

Do I use the default <EMBEDDED>?

Or one of three scanner profiles:
SF_T (Nikon LS5000 Slide).icc
SFprofT (LS-5000ED).icc
SFprofT(Nikon LS-5000).icc

By the way, in the old versions of HDR, ie. 5, 5.5 and 6, there was an IT8 calibration icon, so I guess this has changed in version 8...

confusing profile choices.jpg
confusing profile choices.jpg (103.28 KiB) Viewed 2118 times

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LSI_Ketelhohn
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Re: IT8 calibration for SilverFast HDR

Postby LSI_Ketelhohn » Wed Jun 06, 2012 11:35 am

Dear customer,

Normally you use the <embedded> function.

This uses the profile embedded into the image.
In case of a 16/48/64bit HDR(i) scan the calibrated profile from your scanner will be embedded in the image.
Other images which already have been rendered into a working color-space (e.g. AdobeRGB or Pro Photo) do no longer require the calibrated profile.

kind regards,
Arne Ketelhohn.

wopl
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Re: IT8 calibration for SilverFast HDR

Postby wopl » Sun Jan 03, 2016 11:59 am

Dear all,
even the thread is quite old, it may not be outdated yet.

So I understand, that a profile name is embedded into a HDRi file.
To apply this referenced profile, I need to have the correspending profile (somewhere stored on my current computer). In few years after changing the computer multiple times, I will not find this profile anymore. Is such a correct assumption or is all the profile embedded in each HDRi file?

One different question:
I have calibrated the scanner and then scanned a IT8 calibration slide, build a TIFF.
Reading this IT8 into (calibrated) Photoshop environment "it looks" good. But reading the values (black, white, neutral color deviation), Photoshop tells me not fully using the black and white edges and also shows some grey deviations. Is this normal or anything wrong with my process? After all calibration, the IT8 should be treated as nearly perfect, right?

Thanks
Wolfram

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Re: IT8 calibration for SilverFast HDR

Postby LSI_Ketelhohn » Fri Jan 08, 2016 12:38 pm

Dear Wolfram,

Yes that is correct.

And Photoshop is also correct.
The width of the colorspace of the scanner is much larger than the data of the image.
For the scanner white is "all light gets to the sensor" but the film emulsion always absorbs some light.
For the scanner black is "no light gets to the sensor" however the emulsion always lets some light through.
That is why the raw data is always showing these as grey and it is important to adjust highlights and shadows before the colorspace conversion. Otherwise the image will loose dynamic range.

Kind regards,
Arne Ketelhohn.


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