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If you purchased the CD-Rom version of SilverFast rather than downloading application from the LaserSoft web site you will find two versions on the disc. One is a Photoshop Plug-in and the other a Twain module. Currently the Twain specification does not support full colour management and so this tutorial will concentrate upon the Plug-in version of SilverFast.
Note: the screen-shots are all based on the Mac OS X version of
SilverFast Ai/HDR, although the layout of the various dialogs for the
Mac and Windows platforms is virtually identical.
Before getting into IT8 calibration let's have a quick overview of
the SilverFast Tool Bar and Palette. Some of the buttons on the
Preview Window will only be present on certain scanner models. By way of example - the
Film Format button only appears when the user inserts a film carrier designed to hold multiple film formats. Examples of such a scanners are the Polaroid SprintScan 120 and Nikon 8000. When the multi-format film carriers the actual film format must be selected manually by toggling the button until the format you require is shown.
Special Functions Button Bar
SilverFast Adjustment Tools Palette
Configuring the IT-8 Calibration Module
LaserSoft provide a lot of helpful information on colour management within
the user manual and much of this is replicated on a dedicated PDF file (SF IT8 Manual) to be found in the
SilverFast IT8 folder on your hard disk.
Unfortunately it all relates to SilverFast Version 5 and so users of
Version 6 can easily become confused. Nevertheless, if you haven't already read these documents I recommend that you do
as there are some quite useful information.
Also, if you are in any doubt as to how the SilverFast colour management
system works it might be worth reading the SilverFast
CMS Settings tutorial which has also been revised to reflect the
changes introduced with SilverFast 6 release r37 and upward. Actually with version 6 LaserSoft
have taken the opportunity to standardise all of the colour management
dialogs across the full range of products so the following tutorial
also applies to SilverFast SE, DC, DC Pro and
PhotoCD
Figure 1 - SilverFast Frame Window
Ideally, the Frame window should be configured so that the Filter and
Image Type are as shown above. The Scan Type/Mode can
be set for 36 ->24 Bit Colour (if calibrating a scanner) and
48 Bit HDR Colour (if scanning an IT-8 target to calibrate SilverFast HDR).
Step 1 - Getting SilverFast ready for
calibration
We also want to set SilverFast for our preferred gamma-gradation
value; between 2.0 and 2.2 seem to be the optimum range. Press
Option, select
the General tab and insert the required gamma-gradation value. A short tutorial explaining a method for determining the optimum
gamma-gradation value can be found
here.
Figure 2 - Configuring
Gamma Gradation
The purpose of the: for HDR output checkbox is to enable raw
gamma corrected 48 Bit HDR Colour images to be scanned. The
image will therefore be scanned with the gamma value already applied to
the image but no other corrections are allowed. I suggest that you only use this feature when you want to scan images
directly into Photoshop.
Whilst activating the feature will have no detrimental effect on the
scan but it can present you with a few additional steps (see note below) if
you're intending to use/calibrate SilverFast HDR.
Note: SilverFast HDR has an additional insertion box labelled
Gamma expected in 48Bit/HDR data. The purpose of this checkbox is to enable the user to insert
the gamma value already incorporated into the image file. It is used to apply an inverse gamma curve
which cancels out the gamma of the image and thus prevents the application of a double gamma adjustment. By way of an example -
had you scanned your image in SilverFast Ai with for HDR output
active and at a gamma of 2 you would need to insert 2 into the
Gamma expected in 48Bit/HDR box.
Gamma Gradation in SilverFast
HDR
The above screenshot shows the SilverFast HDR setup required
for the settings I recommended in Figure 2 above. The chosen Gamma-Gradation
value reflects the gamma that I want to use for my FINAL image.
The value quoted in the Gamma expected in 48Bit/HDR data input field is the EXISTING
gamma-gradation value embedded into the raw scan from SilverFast
Ai by virtue of the for HDR output checkbox NOT being
activated.
Although not absolutely essential I usually recommend that all colour management features
are set to
Off. This can be achieved by selecting the CMS tab in the
Defaults window. The following is how I recommend that the dialog should
be configured.
Figure 3 - Disabling
Colour Management
Ideally, you'll will want all the pop-ups to read None and checkboxes to be deactivated before running the
IT-8 module. This is especially important if you're scanning the IT-8 target for use with
SilverFast HDR.
Optional Step (Polaroid 4000 and MicroTek
4000T specific)
Choose the Special tab in the Defaults
window, the dialog shown below
should appear.
When
using either the Polaroid SS4000 or MicroTek 4000T I recommend that the checkbox adjacent to Limit
Gamma Slope is unchecked. This is a change from my previous
recommendation and results from a detailed analysis of the impact this
feature has on scanned images. When Limit
Gamma Slope is activated it has the effect of compressing the
shadow tones so as to minimise dark area noise in very dark images.
Whilst this feature is quite useful for situations were the IT-8 module
is not available it can cause considerable loss of shadow detail when
calibration has been applied. It can also cause severe posterisation in
the shadows.
Step 2 - Calibrating the Scanner
Depending upon your scanner type LaserSoft supplies either a Reflective or
Transparent type target. Additional IT 8 targets can be obtained
directly from
LaserSoft These target will be labelled LaserSoft Imaging
and should contain a reference or Charge number. Newer
targets will contain a
Barcode somewhere along
the bottom edge. The example scan shown below uses a LaserSoft
reflective type IT8 print. Other than the barcode you should
find that the appearance of IT8's from other vendors is broadly similar. If calibrating a scanner in
SilverFast Ai place/insert the IT-8 calibration print/slide onto/into the scanner.
SilverFast HDR requires that the image be pre-scanned in SilverFast Ai
or another third party scanning application.
We begin by pressing the Prescan button.
Prescan/Scan Buttons
A Prescan image of the IT-8 target should now appear on-screen. Make
sure that it appears in the Landscape format. If it doesn't you
should rotate or flip the image as required. Failure to have the IT-8
target in the landscape format may result in an error message.
From the menu strip shown on the left-hand side of the
Preview window, Press the Calibration button
 .
Cropping of Prescan IT-8 Target
The prescan image MUST now be cropped as indicated by the red
boundary in the screenshot shown above. Each corner of the cropping
marquee is independently adjustable so a slight skewed or rotated scan
can easily be cropped so that all of the coloured/neutral patches are
fully covered. From here on the process of calibration is relatively
straightforward.
If the following warning appears to advise you that the Internal RGB
Profile is missing; don't panic as it's really telling you that the
steps taken in Figure 3 needs to be reversed once the
calibration process is completed. Click OK and proceed.
Next the main IT-8 Calibration dialog will appear. This dialog is pretty
much self-explanatory with step-by-step instructions appearing at each
stage throughout the process.
Remember that it's important that you frame/crop the relevant area of the image as
shown (i.e. landscape format). SilverFast displays shows a grid over the
prescanned image so you should be able to quickly confirm that your
cropping is accurate.
Press the Start
button and the scanner begins the greyscale balance, once this is
complete SilverFast will check the scanned image for the presence of a
LaserSoft compatible barcode. If the barcode is found SilverFast will search your hard drive or the LaserSoft web
site for the appropriate reference data file. If the file is found
SilverFast automatically proceeds to adjust for the
colour balance and that's it. If the reference file can't be found (usually
because the IT8 target was not supplied by LaserSoft) the following
warning appears. You'll need to select the correct reference data file
manually before continuing.
Once completed SilverFast will inform you that the process of
calibrating the scanner has been successful and you'll be asked to save
the ICC profile. Make sure that you give the profile a name that is
easily recognised:
To complete the calibration process simply choose OK
from the IT-8 Calibration dialog. If the calibration has been successful and the profile created is
available for use. You should now see that the calibration button
has changed to become more coloured than before; i.e. it will look like
 .
The final step of setting up the SilverFast IT-8 colour management
system takes us back to CMS dialog of the Defaults window.
Step 3 - Getting it all together for output to
Photoshop
The previous step described how to calibrate the scanner. However, that's only half the story. We have only described the source colour space (i.e. the scanner);
we now need to make sure that what we see
in the Preview window and what gets sent to Photoshop are matched (the
destination colour space).
Press the Option button followed by the CMS
tab in the Defaults window and the Colour Management
should appear as follows:
Figure 4
The scanner profile in Step 2 will automatically be inserted into the
appropriate location (red star)
The next phase is to set the CMS dialog as follows: -
Colour Management
-
Input
- > Internal - should have automatically been
set to Colorsync (Mac) or Image Colour Matching (PC)
-
Internal - > Monitor - should be set to
Automatic (see note below)
-
Internal - > Output - should
normally remain RGB
Profiles for
ColorSync/ICM
-
Input - the correct scanner profile is
automatically inserted
-
Internal - should be set for
your preferred
Photoshop working space, e.g. Adobe RGB (1998), ColorMatch, etc. (see
note below)
-
Gray
- if you have a greyscale profile select it otherwise the Generic
Gray profile will suffice.
-
Output/Printer - will be greyed out and therefore cannot
be changed.
-
Rendering Intent - ideally you should leave it at
Perceptual although some users prefer Relative
Colorimetric for artwork
Embedded ICC
Profiles
-
Embedded profile (not present on SilverFast Ai) - since you are using the IT-8 calibration
module this will read None. You can't change it and if it
shows anything other than none you will need to alter your scanner
application to prevent profile embedding
-
Embed ICC profile - this should be checked
Figure 5 - Final Configuration of CMS Dialog
Important note: When
Internal->Monitor is set to Automatic it takes its cue for accurate
previews from the RGB Working Space as defined in Photoshop Color
Settings. Therefore it is essential that the SilverFast Internal
profile matches the PhotoShop RGB Working Space.
If Internal -> Output is set for RGB then the remaining settings
(e.g. Output/Printer and Plug & Play CMYK) cannot be altered. Finally click Apply
followed by OK. You're now ready to enjoy the benefits of
scanning images using a colour managed workflow.
Remember the Embed ICC profile checkbox MUST be selected and your
Photoshop setup for handling mismatched profiles must be
configured as described in the essay entitled Configuring
Colour Management in Photoshop 5,
Photoshop
6 and Colour Management or Photoshop
7 and Colour Management . If you haven't read these
then it is probably better that you do. Choose the version of Photoshop
that you use by selecting the appropriate underlined text.
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