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.
For SilverFast, that means using HDR, another application entirely. Metadata Editing. Unlike the Raw files from a camera, Raw scan files do not enjoy the benefits of metadata editing. SilverFast HDR Studio 8 is the ideal complement to SilverFast scanner software. Scan your images easily into 64bit/ 48bit HDR(i) RAW data format, which contains any ascertainable image information. Anytime later, optimize many images simultaneously with SilverFast HDR Studio 8. WorkflowPilot - a step-by-step assistant for every workflow. Oct 23, 2011 Whacked SilverFast HDR CMS Tab.png Whacked RGB Test.jpg I should again point out that the above image will look quite normal if viewed in a web browser (or any program) that does not support colour management (this points to the fact the RGB values are somewhat similar to the sRGB colour space). So it's indifferent whether one works in positive or negative mode, what negafix profile is selected, the applied gamma, colour corrections, exposure corrections, or the amount of the frame that is scanned - the resulting HDR file will be exactly the same because those are all post-scan processing that doesn't get written to HDR and can be done.
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 Typepop-up and then choosing 48 Bit HDR Colour, as shown below.
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.
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.
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 Aiwill 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.
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).
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.
Silverfast Hdr Studio Review
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 DefaultsGeneral dialog looking similar to that shown below.
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.
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.
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.
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.
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 and/or gradation button will have changed colour (e.g. ).
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 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.
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.
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 tool. Once you find the required points in the image then simply click them with either the highlight 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 correctionSelective Colour correctionare 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.
Whiterocks and Cloud Pattern - North Antrim Coast
Editing the Prescan in SilverFast Ai and HDR
This page provides a quick overview of the toolbars and deals with the basic tonal correction tools, Histograms, White and Black Point tools, and finishes with the Auto Colour Correction tool.
Know your tools!
Adjustments Toolbar
No Colour Management Enabled | Colour Management via Embedded ICC Profile | ColorSync/ICC Colour Management Enabled |
Variations of the Auto Adjust Tool
Special Functions Toolbar
Assess the Image
After pre-scanning the image it is generally helpful to establish the tonal range of the original and the location of the darkest and lightest pixels. Using the Black or White point tool located at the bottom of the Special Functions toolbar we can easily find dark and light pixels. The location is identified with a red circled cross-hair. If there is a large numbers of equally light pixels at this point then pressing the White button will cause ALL of these pixels to turn BLACK. Large numbers of equally dark pixels in the image will show as WHITE when we press the Black button. I find this a much more intuitive approach than Photoshop's clipping display since it only effects those pixels that are likely to be of interest.
SilverFast at Work (Figure 1)
As shown in following screenshot we can also see the actual RGB/CMYK/Lab values for these pixels in the Densitometer window. The group of numbers shown circled in red represent the original values. The numbers on the right represent the corrected values. Obviously since both the left and right number groups are equal this screenshot represents the image before any corrections have been applied.
Densitometer
If a single densitometer was all that we got then there would be little to celebrate as the information and location of the dark and light pixels would be lost as soon as we clicked another area of the image with the mouse tool. However, a really neat trick is to lock the location of these pixels on the pre-scan and provide a dedicated densitometer - How? Easy! - Hold down the Shift key and click on either the White or Black point tool and presto a new dedicated densitometer is created. The location will also be displayed on the image by a small cross-hair with an associated number
Fixed Point(s) Densitometer
Furthermore, we can open the Levels or as LaserSoft call it the Histogram at any time and see the actual spread of data from dark to light for each of the channels (RGB, CMYK, etc.). The following screenshot shows the ideal method of display for best practice colour editing (i.e. all three RGB channels in view). Here we can see the 3 colour channels.
Histogram - No Adjustments
What does the above histogram tell us? Firstly that the sample image is not full-scale, i.e. the image has no pixels at level 0 nor 255. We can also see that the shadow and highlights are not completely neutral. So the histogram provides us with confirmation of what the Black/White point tool and densitometer was indicating.
Should I use Auto Adjust?
Lots of SilverFast users shy away from the Auto Adjust tool thinking that it is going to damage their images. Maybe it will and maybe it won't - but the USER has control. By getting a basic understanding of how Auto Adjust works we can save ourselves a lot of agony. LaserSoft have provided an exceptionally powerful tool and we should learn to use it. Note that in the screenshot shown below I show Auto Contrast as OFF - this is my normal approach - others are free to choose otherwise (Experiment!). The settings shown inside the red boundary are the KEY to ensuring that minimal data is lost whilst getting the best from a well exposed and normal toned original. Read Chapter 5 of the user manual, read it again, then configure the Auto section of the SilverFast Defaults window correctly and you won't be sorry.
Tips
setting the highlight offset to 0 is not a good idea since the highlight pixels will be clipped to level 255 upon application of Auto Adjust.
setting the shadow offset to100% is not a good idea since the shadow pixels will be clipped to Level 0 upon application of Auto Adjust.
Auto Defaults (Figure 2)
The Histogram
The following screenshot shows the histogram for my sample image after pressing the Auto Adjust button (using the settings I suggested above). Simply pressing the Auto Adjust button will mean that the image highlight and shadows will be optimised such that the spread of image data is more evenly distributed (figure 3). Notice how the shadow and highlight points in the histogram are all equal which means no colour correction has been applied to the image; I'll explain why in a moment.
Histogram after Auto Adjust (Figure 3)
We can also see from our previously created densitometers that the values for the dark and light points have changed after applying the Auto Adjust tool.
If the original pre-scan was assessed as being dark/light by SilverFast then an appropriate correction will automatically be applied (figure 4). In the screenshot shown below I show an adjustment of -4 (brighten the image). Positive numbers will darken the image.
Histogram after Auto Adjust (Figure 4)
Important note about Auto Adjustment tool!
For SilverFast users with IT8 calibration or a customised ICC scanner profile SilverFast will ignore any colour casts it finds in the pre-scan and so Auto Adjust will simply correct the tonal range of the image. If on the other hand you are using SilverFast without the benefit of calibration 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 with a green asterisk (see Figure 2 above for an example). 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 and the colour cast will be retained in all its glory. 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 (see Auto Adjust tool variations on page 1).
Colour cast removal can be fine-tuned at any time using the Color Cast Removal slider. The screenshot below shows how smart SilverFast is at removing colour casts using the Colour Cast Removal slider. I push one slider and SilverFast decides which channels, if any, require adjustment to neutralise the cast. As mentioned above; no colour cast removal is Zero % and complete colour cast removal is 100%. In the example below I show 75% of the cast has been removed. Remember not all colour casts are bad, some are an inherent feature of the image (sunset).
We can also manually adjust the vertical sliders for each channel by simply grabbing each in turn with the mouse or as a group (highlight, shadow or mid tone groups) by grabbing the appropriate triangle directly under the histogram.. Experiment in this dialog and you will learn lots of neat tricks to refine your images.
So how much damage has been done to my Image?
Are you worried about trashing important image data? Do you need to know how the image data will appear in Photoshop? With the Levels Histogram open simply hold down the Alt/Option key and watch the data in the histogram spread. It's probably better to use the combined histogram for this test as it will more likely be comparable to the Photoshop levels dialog.
Histogram for Uncorrected Image
Histogram for Corrected Image
Notice that through careful choice of values for the Shadow and HighlightThreshold in the Auto Defaults dialog (figure 2 above) I have managed to ensure that no clipping occurs at the end points. In this example the end points were defined as 98% for the shadow which equates to Level 5 and 2% highlight which equates to Level 249. If we can manage to avoid clipping at the scan stage we can be confident that saturation of individual colour channels has also been avoided
Note that any spikes (there might not be any) in the histogram represent values that have been rounded (made the same) and usually results from the high to low bit conversion. Gaps in a histogram represent data values that have been lost. In simple terms pressing the Alt/Option key when viewing the histogram will represent the 8-bit data being output to Photoshop. It's also important that we remember EVERY edit and conversion will loose data. Even applying the basic and very necessary gamma adjustment to the raw scan will loose data.
Silverfast Hdri Raw
Conclusion
So what have we learned from this tutorial:-
Silverfast Hdr 8
The basic tools
How to assess the Pre-scan
Find and store the location of darkest and lightest pixels
Configuration of the Auto Adjustment tool
How to use the Levels Histogram tool
How the maximise the range of the scan
How to brighten/darken the scan
Automatic and manual Colour Cast Removal
How using the Alt/Option key and Levels Histogram we can preview the 'edited data' being sent to Photoshop.