Color Calibration Trouble and Questions

[dylan]

Im running photoshop 7 and silverfast AI 5.5 with it8 calibration. Im using winxp and the epson 2450.

1) Do i need seperate it8 targets to calibrate and use for each type of slide film? i dont want to be correcting for each films inherent color differences. ie: i dont want to "correct out" the natural over saturation of blue for example in fuji films.

2) what is the difference in silverfast between selecting a) scanner-internal = calibration and b) scanner-internal = icm with the profile for icm selected as the same icm profile created during calibration?

- the letter "c" in the middle of the auto button dissappears if i use option b) above.

- in my understanding of how silverfast works, these 2 setups should produce the same results.

- using scanner-internal = icm , i would be able to use other profiles created through other programs (for example Little CMS) or the generic epson profile, right?

3) if the it8 calibration works, why do i need the AUTO function or the color caste removal slider under the histogram? shouldnt the profile be correcting my scan to what color is actually on the slide? (i am wanting to produce a scanned image that is a reflection of the actual slide, be it good or bad, and then do any necessary adjustments from there)

Thanks for any help on the above, hope I was clear. I had a good look for answers on the forum, but it is large so if the answers are elsewhere in the forum, please give me a link. Thanks all.

[LSI_Noack]

Dear Dylan

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To put in everyday speech: The IT8 calibration option tells the software how your scanner sees color.
So, while you do calibrate according to the quality of the light source within the scanner and would need separate targets for the individual lights sources present (e.g. flatbed scanner with TPU), you don't calibrate for a specific film material.

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In SilverFast 6 you no longer would have this problem; the "scanner-internal=calibration" option is regarded as deprecated in SilverFast 6 - you want to use the ICM workflow instead.
When you are using "s-c = calibration", a change of an ICM profile will not be reflected by SilverFast.
Yes, with an ICM workflow you are able to use other profiles, but please note that these are generic profiles and according to the manufactural bandwith might not necessarily lead to the results you want to achieve.

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The IT8 calibration is not about removal color casts, but ultimately about achieving same color values on all calibrated devices (scanner, monitor, printer) as far this is technically possible (e.g. you cannot print every color a monitor can show).
Say, you have a slide with color cast due to age. And you don't want SilverFast to have the image altered when a digital representation of your slide is created: You'd need IT8, but you wouldn't want color cast removal.

Please note also:
During the IT8 calibration process all automatic functions and individual adjustments a user may have set are disabled to generate an "as seen by the scanner" profile of your scanner.