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Using SilverFast HDR

SilverFast Box

Tutorial - 2

Basic steps to optimising high-bit Scans

By Ian Lyons

A Computer Darkroom Review

A question often asked of me is "why do we need SilverFast HDR?" Well, the simple answer is many professionals prefer to scan their images in "raw high-bit" and then save them to a Tiff file for latter processing. SilverFast HDR was designed to enable  the user to "process" existing image files (typically 16-bit Tiff or JPG files).

 

Unlike SilverFast Ai which has individual versions associated with individual scanner models HDR is designed to be used without a scanner. SilverFast HDR requires that your image have already been pre-scanned and saved as Tiff or JPG files. With SilverFast HDR the scanner operator can batch scan any number of images without worrying about colour/tone editing until such times as the edited images are required. The individual responsible for scanning might not even be concerned about final processing since this task can be passed-off to a more skilled person.

This tutorial will demonstrate two workflows for capturing raw high-bit scans from SilverFast Ai. It  also shows how to carry out a few basic corrections to the scanned image in SilverFast HDR.

The screenshots are all based on  Mac OS X of SilverFast Ai and SilverFast HDR. Nevertheless the basic layout of the various dialogs, etc. should be familiar to users of other operating systems

SilverFast Ai Scanner Set-up

Configuring SilverFast Ai to output your scans in raw high-bit mode isn't that difficult, but there are a few quirks that if left unattended too will cause no end of grief. If the steps outlined below are followed all should be okay.

In the following I assume that you are using Photoshop and are familiar with the SilverFast interface, although the screenshots should make things a bit easier to follow.

Step 1 - Getting SilverFast Ai ready for high-bit scanning

First we want to get SilverFast Ai set for raw 48-bit color output (LaserSoft call this 48 Bit HDR Colour mode). This is achieved by simply selecting the Scan Type pop-up and then choosing 48 Bit HDR Colour, as shown below.

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Setting SilverFast Ai for High Bit Output

You will notice that once 48 Bit HDR Color has been chosen ALL the colour adjustment tools are disabled, again this is normal, remember in high-bit mode you can't make, nor do you want to make any adjustments to the raw scan.

Next we want to get SilverFast Ai set for our preferred gamma-gradation setting. Anywhere between 1.8 or 2.2 seem to be the optimum values.

  • Press Option and then select the General tab.
  • Insert the required gamma-gradation value.

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  • If using SilverFast HDR with the IT-8 Calibration module or a custom created scanner profile the checkbox  labelled for HDR output should be left in the default unchecked state.

Important Note:  If you intend to scan negative type films and later use NegaFix it is again recommended that:- for HDR output is left unchecked and that you configure the CMS dialog as shown here - Click logo for instructions

Step 2 Configuring colour management for HDR colour mode

Different users appear to have widely varying views on how SilverFast Ai should be configured so that the raw HDR colour images are suitably prepared for later processing in SilverFast HDR. I'll describe two alternative workflows and have identified them according to two common user groups. Choose the one that best fits your needs, but don't try to mix the setting between them.

User Group 1 Configuration

This configuration is ideal for SilverFast Ai users who wish to save their 48-bit HDR Colour images with NO profile embedded and who will subsequently edit the high-bit images in a fully IT-8 calibrated version (optional extra) of SilverFast HDR. The raw scanned images resulting from this workflow will be very dark; this is normal.

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SilverFast Ai CMS Configuration 1

(48-bit HDR colour mode - don't embed a profile)

The CMS dialog should be configured as per the screenshot shown above, however, I have provided some further information below so that the choices may be better understood.

Colour Management

  • Input - > Internal - should be set to None. SilverFast Ai will not colour manage the image.
  • Internal - > Monitor - should be set to Automatic
  • Internal - > Output - should  be set to RGB

Profiles for ColorSync/ICM

  • Input - choose None. If a profile is selected it will be embedded in the exported/saved image and will likely conflict with the calibration profile associated with SilverFast HDR.
  • Internal - should be set for "your" preferred Photoshop working space, e.g. Adobe RGB (1998), ColorMatch, etc. As with Internal ->Monitor described above this selection will ensure that the preview image is displayed accurately on your monitor.
  • Gray - Not Important
  • Output/Printer - will be greyed out and therefore cannot be changed
  • Rendering Intent - ideally you should choose Perceptual or Relative Colorimetric

Embedded ICC Profiles

  • Embed ICC Profile - Uncheck!

Using the above configuration there will be no embedded profile.

User Group 2 Configuration

This configuration is ideal for those users who don't have any particular concerns about limiting the gamut of their original scans to the Photoshop working space. It's ideal for those who are using the SilverFast Ai IT-8 module; a third party calibration profile; or don't wish to leave colour management to SilverFast HDR.

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SilverFast Ai CMS Configuration 2

(48-bit HDR colour mode - embed work space profile)

The CMS dialog should be configured as per the above screenshot, however as before, I have provided some further information below so that the choices may be better understood. Note that you should begin by configuring the Profiles for ColorSync/ICM section.

Colour Management

  • Input - > Internal - Choose ColorSync/ICM.
  • Internal - > Monitor - should be set to Automatic - This setting ensures that the preview display will accurately reflect the image colours, tone and brightness.
  • Internal - > Output - should be set to RGB.

Profiles for ColorSync/ICM

  • Input - If Input -> Internal was set to ColorSync/ICM select the appropriate Scanner Profile otherwise None is acceptable.
  • Internal - should be set for "your" preferred Photoshop working space, e.g. Adobe RGB (1998), ColorMatch, etc.  Alternatively an archiving colour space such as EktaSpace or Kodak Pro Photo RGB could be selected. The selection made here will be the profile embedded within the exported/saved image.
  • Gray - Not Important
  • Output/Printer - will be greyed out and therefore cannot be changed.
  • Rendering Intent - ideally you should leave it at Perceptual or Relative Colorimetric

Embedded ICC Profiles

  • Embed ICC Profile - this should be checked

The embedded profile will be "your" chosen Photoshop working space as selected in the Profiles for ColorSync/ICM pop-up menu.

If your output is set for RGB then the remaining settings cannot be altered. Finally, click Apply followed by OK.

Step 3 - Saving the high-bit scan in SilverFast Ai

This step is where we decide on whether we want SilverFast Ai to scan directly into Photoshop or to save the raw image as a Tiff file. There is no definitive "right" way, and so individual users will make the choice depending on their preferred workflow. Nevertheless, I prefer to scan the raw images to file and save them within SilverFast Ai. The following screenshot shows the necessary settings.

Select the General window and then choose Scan Mode. From the pop-up menu select Normal (File).

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Saving the Raw scan out to file

Step 4 - Making the scan

From the Frame window select your scan resolution, etc. Unless you want to rescan the image again at some time in the future it's best to choose your scanners maximum optical resolution. Also make sure the Q-factor is set to "1" and that the Filter and Image Type are set for None and Standard respectively.

You can now press the Prescan button and watch the image appear on screen. Be aware that a full frame 35mm scan at 4000ppi is going to take upwards of 110MB of memory/hard-disk and so will be slow to appear. For the larger medium format scans, i.e. 6 by 9-cm the memory/hard-disk requirement is substantially higher. The last step before choosing the scan button is to crop your image. Make sure that you get all that you want into the scan frame. If the Prescan looks dark or even the wrong colour don't worry you cannot nor do you need to fix it, yet!

Finally, press the Scan RGB button and let SilverFast Ai and the scanner do their work. You will be prompted for a file name and make sure you choose to save the file in the Tiff format.

Prescan and Scan RGB Buttons

Configuring SilverFast HDR

To all intents and purposes SilverFast HDR operates in the same way as SilverFast Ai. On first opening SilverFast HDR you will probably be prompted to open an image, whether you choose to ignore this step or pick an image (any image will do) is pretty much up to yourself, but what comes next shouldn't be ignored.

Step 1 - Reconfiguring the SilverFast HDR Defaults

The first step in the set-up process is to switch off  any Filters that may be active.  Also check that  the Q-Factor is set to "1" as is shown below.

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SilverFast HDR - typical settings

Step 2 - Setting the Gamma and Output Colour Space

For the purposes of this tutorial I will assume that you are intending to process positive type images scanned in SilverFast Ai and that these images have NOT been gamma adjusted; i.e. the for HDR output checkbox in SilverFast Ai that I mentioned earlier was left in the default unchecked or Off state.

Press the Option button and then select the General tab. For most users the Colour Model should be set to RGB.

The Gamma-Gradation should be set for a value between 1.8 and 2.2. Ideally the Gamma expected in 48Bit/HDR  should be left at the default of 1. The for HDR output checkbox is best left unchecked.

Note: The purpose of the Gamma expected in 48Bit/HDR insertion box  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.

Setting the Q-Factor to 1 in this dialog doesn't seem to effect what you choose on the main dialog, but it's better safe than sorry, set it to 1.

You should end up with the Defaults General dialog looking similar to that shown below.

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SilverFast HDR Gamma-Gradation

Step 3 - Setting the CMS dialog

As with SilverFast Ai we find that depending upon our chosen workflow we need to configure the CMS dialog differently.

User Group 1 Default CMS Settings

The following screenshot shows the required CMS setup when the image was scanned with no profile embedded. Using this method SilverFast HDR will be handling ALL colour management using either a SilverFast IT-8 calibration profile or a custom created scanner profile.

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SilverFast HDR CMS settings for User Group 1 Configuration

Colour Management

  • Input - > Internal - should be set to ColorSync/ICM

  • Internal  - > Monitor - should be set to Automatic.

  • Internal  - > Output - should be set to RGB.

Profiles for ColorSync/ICM

  • Input is set to your scanner profile.

  • Internal - should be set for "your" preferred Photoshop workspace, e.g. Adobe RGB (1998), ColorMatch, etc.

  • Gray - Not Important

  • Output/Printer - will be greyed out and therefore cannot be changed.

  • Rendering Intent - ideally leave at Perceptual or Relative Colorimetric

Embedded ICC Profile

  • Embed ICC Profile - this should be checked.

  • Profile to embed will read as your selection for Photoshop, here we see my choice of Adobe RGB (1998).

User Group 2 Default CMS Settings

The following screenshot shows the required CMS setup when the image was scanned with either the Photoshop working space or a scanner profile embedded. Using this method SilverFast HDR will utilise the embedded profile to ensure that the raw image is correctly rendered in the Preview window.

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SilverFast HDR CMS settings for User Group 2 Configuration

Colour Management

  • Input - > Internal - should be set to Use Embedded Profile

  • Internal  - > Monitor - should be set to Automatic.

  • Internal  - > Output - should be set to RGB.

Profiles for ColorSync/ICM

  • Input - will be greyed out and therefore cannot be easily changed. It need not be set for anything other than the default None since the profile embedded in the image tells SilverFast all that it needs to know about the image source.

  • Internal - should be set for "your" preferred Photoshop workspace, e.g. Adobe RGB (1998), ColorMatch, etc.

  • Gray - Not Important

  • Output/Printer - will be greyed out and therefore cannot be changed.

  • Rendering Intent - ideally leave at Perceptual or Relative Colorimetric

Embedded ICC Profile

  • Embedded Profile - this will be the profile that was embedded into the original scanned image

  • Embed ICC Profile - this should be checked.

  • Profile to embed will read as your selection for Photoshop, here we see my choice of Adobe RGB (1998).

Step 4 - Opening the "raw" scan

We're nearly home; the final stages of getting our "raw" high-bit scan into HDR are only a few mouse clicks away.

  • Select Open and then navigate to the folder were you stored the scanned image. Once the image opens you will find that it may need to be rotated, flipped, etc.

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The finishing touches!

Everyone has their own views as to what needs to be done to an image before it's exported into Photoshop. The following are few hints as to which tools offer the quickest and easiest route to a reasonably colour/tone accurate image. Obviously you should experiment by yourself, it's only through such trial and error that you can ever hope to learn SilverFast.

Before I discuss some of the tools we have one more dialog to configure, the Auto settings dialog. You can access this dialog by simply pressing the Option button followed by selecting the Auto tab. The following screenshot shows "my" settings. They are, excepting two the default settings.

 

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The Colour Cast Removal tool is a new feature introduced in version 5.2, and comes in handy with some images. When set for 100% any colour cast (as determined by SilverFast) will be totally removed. Sometimes this a good thing, on others it makes for a horrible effect, pick your values wisely, but something in the order of 10% to 20% might be enough for most images. You won't see the effect immediately or might never see any at all, so don't expect any on screen change to your image yet.

Next,  I deselect the Auto Contrast, I have no liking for this feature, but you may feel differently. You can refer to the SilverFast manual for a more comprehensive explanation of each of the remaining settings.

The Tools in use

The tool bar running across the top of the Frame dialog is the real powerhouse of SilverFast. I'll only be touching on a few adjustment tools, but at least should get some idea of where to start.

 

SilverFast Adjustment Tools Palette

Automatic Tone and Colour Correction

We can identify whether SilverFast will or will not automatically apply colour correction by checking which form the Auto Adjustment (aperture symbol) takes in the Adjustments toolbar - and both mean that Auto Colour Correction will NOT take place and means that it will.

So our first step in colour/tone correcting the image is to press the Auto Adjust button. Users with IT8 calibration or a customised ICC scanner profile will find that SilverFast ignores any colour casts it finds in the pre-scan and so Auto Adjust will simply correct the tonal range of the image. Usually the shadows will darken and the highlights brighten. With some images the midtones can also change. We can see what has changed without even inspecting the image because either the histogram  b2 and/or gradation button will have changed colour (e.g. b3).

If on the other hand you are using SilverFast without the benefit of IT-8 calibration or a custom ICC profile then SilverFast will automatically remove any colour casts found in the image (not a good idea for sunsets). The user can preset the amount of automatic colour cast removal by inserting a value into the Color Cast Removal popup shown in the Histogram dialog below.  The default value of 100% will completely remove the colour cast an a value of 0% will leave the cast untouched. Alternatively we can hold down the Shift key when pressing Auto Adjust B1  and the colour cast will be retained. 

Remember the Colour Cast Removal option mentioned above, well now you should appreciate why I suggested values between 10% and 20% as starting points. If we look at the Histograms below it can be seen that in one the system has cancelled out only 20% of the colour cast. Had I set a higher or lower value then the Histogram would reflect that. Also note that you can fine tune the degree of cast removal by dragging the slider left or right. The second Histogram shows the effect of leaving the default value of 100% colour correction.

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Auto Colour Correction at 20% Auto Colour Correction at 100%

The black points and white point have also been set automatically as per the values we chose in the Auto dialog above.

Next we look at the Gradation Curves dialog for the same image as was used for Histogram correction. The first screenshot shows that only the gradation (or gamma) has been modified by the automatic settings and the second shows the effect of leaving Auto Contrast ON. As with all SilverFast adjustment tools we can make further adjustments as needed.

Image Image
Auto Contrast OFF Auto Contrast ON

As with Photoshop we can pull the master or individual colour channel curves in any way we choose thus optimising contrast, etc. We can achieve this by simply moving the gradation slider or just grab the curve and pull it. The brightness and contrast of the image can be further refined, as can the highlight and shadow points. Remember all of this is occurring on a high-bit image, so the amount of image data being trashed is minimal. Better still, the original scan will never be changed, it remains intact.

Manual Tone and Colour Correction

The above method was based upon automatic correction of the image with some manual fine-tuning. For those who prefer manual correction SilverFast Ai and HDR have the tools. I mentioned the highlight and shadow points above and how they were automatically adjusted, but say you didn't want them adjusted automatically, or worse didn't know were they where. Not a problem, finding the white or black point in an image is a simple matter of clicking with the white or black square on the  b4 tool. Once you find the required points in the image then simply click them with either the highlight  b5 or shadow tool, and the image highlight or shadow will be brought to neutral. The centre of this icon can be used to set midtones to neutral. Again the gradation curves dialog has a major part to play in getting colour and tone correct, so experiment.

The remaining icons on the toolbar, i.e. Global Colour correction b6 Selective Colour correction are discussed in Tutorial 3 and well worth investigating all the same. Further guidance on basic image editing in SilverFast can be found HERE

Once you are satisfied with the corrections it simply a matter of transferring the corrected image to Photoshop for printing, saving whatever. This is achieved quite simply by pressing the Scan RGB button.

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Whiterocks and Cloud Pattern - North Antrim Coast

 

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