The dynamic range of each stage (capture, scanning, editing and storage) plays a crucial role in the quality of the results. In general, technologies with greater dynamic range produce better results.

The objective of Multi-Exposure is to enhance the Dynamic Range of scans from film material since a scanner rapidly reaches its limits with single scan acquisition. Because no substantial improvement of dynamic range can be achieved with reflective scans, Multi-Exposure works with film material only.

Todays film material, whether black&white or negative color film or slides, provides a very high dynamic range, because film manufacturers added more layers of different sensitivity.

As a matter of fact, a regular positive film, more commonly called slide film, holds a contrast range of up to 8 f-stops. A well exposed and developed negative can hold up to 12 fstops.

The Problem

The reliable capture of tone in the digital image of a photograph is influenced by many elements within the scanner.

• If the dynamic range in the captured scene exceeds the contrast range of the scanner, the details cannot be captured with that device despite the scanner's bit-depth capabilities.
• The results are lack of information in highlights and shadows.
• The noise and grain reduce the visual quality of digital images and printouts.

SilverFast Multi-Exposure

In order to meet or match the dynamic range of the photographs being scanned, three SilverFast products can be used in conjunction with each other:

1. SilverFast SE Plus or SilverFast Ai Studio captures the maximum dynamic range using the Multi-Exposure feature.
2. SilverFast HDR-Studio processes and optimizes the HDR-scan for output and archive.

SilverFast Multi-Exposure captures the maximum dynamic range of the original by performing multiple scans with different exposures. This is clearly different from the Multi-Sampling procedure, in which multiple scans are performed to identify and remove random noise patterns in an image. The new Multi-Exposure feature not only eliminates noise but also increases the dynamic range of the hardware.

Multiple exposures can eliminate noise and also reveal more fine image details in the hightlights and shadows. This will be most noticable in the sharp specular highlights and pronounced textures.

The Advantage

Scanning interior photographs and trying to capture subtle nuances in the highlights and shadows can be frustrating. At best, it requires time and effort and sometimes may seem impossible. This is entirely dependent on the effective dynamic range of the scanner, which is essentially the scanner's ability to capture different tonal values in an image. So, if the software enables the hardware to capture more details in the highlights and shadows, it effectively increases the dynamic range. The graph displays the increase in dynamic range achievable using SilverFast Multi-Exposure with several different scanners.

As a reference, a dynamic range of 2.0 means the scanner is capable of reproducing a contrast ratio of 100:1, a dynamic range of 3.0 represents a contrast ratio of 1000:1. In our dynamic range tests according to ISO21550 (international standard) the Epson V700 flatbed scanner was capable of scanning a dynamic range of 3.9, which is a contrast ratio of almost 7,000:1. This means that the highlights can be 7,000 times brighter than the shadows and SilverFast Multi-Exposure will still capture details. These two graphs illustrate the increase more drastically in luminance values.

This kind of dynamic range is usually achieved only with drumscanners, which can cost up to many times the price of a flatbed or film scanner.

For best possible results please assure that the image is not moving during the multiple scan passes: Either use a film template or fix the image with tape. This is needed to prevent the film from moving due to the vibrations and movements of the scan, otherwise additional scan passes would scan different crops.

Do you really need HDR Imaging and Multi-Exposure?

HDR Imaging could play a major role in the next dimension of digital imaging. In the coming decade, more and more HDR technology will arrive and change the way images are captured, processed, edited, displayed and stored. SilverFast is proud to be a part of this process, providing an HDR imaging solution and upgrading technology that already resides on many desktops today.

Expectations are that HDR software will lead to an increase in productivity and greater expressiveness.

Make sure that your scanner supports Multi-Exposure.

Multiple reflective or transparent images can now be selected, scanned and optimized automatically using the new Automatic Frame Detection.

The workflow is very simple:

1. Perform a prescan or preview the image.
   SilverFast will initially display one large frame for the entire preview window.
2. Select AutoFrame button to activate the auto frame detection.
3. SilverFast now generates individual frames for each image.
4. The auto adjust will then optimize all images automatically.
5. Additional corrections such as sharpening, image size or resolution can be done individually.
6. All images will be corrected by a single scan. The batch function may also be used for this purpose.

Example: automatic frame detection in SilverFast Ai

Prescan without (left) and with (right) automatic frame detection

The automatic frame is available for all SilverFast 6.5 versions and is best suited to identify images which are positioned on the flatbed without an image holder.

In those cases where an image holder is required, the recommendation would be to generate an according template and save the positioned frames, "General / Save Frame".

The AutoFrame Alignment was developed and designed to offer the user an extremely efficient, yet convenient scanning experience. When positioning multiple images on the scanner, AutoFrame Alignment and the frame detection will not only "find" and frame the originals, it will align them in a rectangular order. Pictures will automatically be rotated for straight edge alignment. Manually cropping and aligning images in another editing application is no longer necessary.

SilverFast's intelligent detection and alignment algorithms perform these actions with a simple selection. Image frames can also be arbitrarily rotated for further fine tuning.

SilverFast's AACO is an excellent tool for the correction of dark, high-contrast areas of the image while preserving the details in the highlights. It operates automatically when selected but can also be manually manipulated. The intensity and the complexity of the shadows, which are to be lightened, can be adjusted without affecting the highlights of the image.

Scanner noise comes in random patterns and is mostly visible in the very dark areas of the scan. This is where the CCD is getting very little light to work with, so the difference between the signal from image details and the background noise from the CCD and other analog components is too small, resulting in image noise. If the image is scanned only once (normal scanning), the noise will be imprinted on the scan. When scanning with multiple sampling, the same image is rescanned repetitively. Since the noise patterns randomly change each time, SilverFast can differentiate the noise, cancelling it out if inconsistencies are present.

Scanner noise is clearly visible Scanner noise is eliminated

How does it work? With multiple sampling turned on, SilverFast will perform either 4, 8, or even 16 scans during scan time. You can specify the count, usually the more the better. After performing the scans, the single images are averaged together into one image. Since noise is random, a special averaging procedure will cancel only the noise but leave the image details untouched. There is a problem associated with this process: Every scan might not exactly be in the same position with reference to each other, so normal averaging would blur the resultant Multisampling scan. That is why Silverfast SE Plus has an intelligent auto-alignment, so no blurring effect can occur.

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A new option in NegaFix offers a fast and simple solution to the existing issue of residual color casts in negative film profiles. Distracting color casts or remnants of the orange mask can be removed quickly. SilverFast's new automatic CCR (Color Cast Removal) neutralizes these casts with a single click on the CCR button as shown below.
This function is easy and efficient to use and provides immediate results. All SilverFast versions which are presently equipped with NegaFix contain this improved feature. New NegaFix film profiles have been added, e.g.: CityplaceFuji Pro 160S / Kodak 100UC. Effect of CCR The effects of CCR are already visible before any negative profiles have even been selected:
CCR turned off CCR turned on
With the help of more than 120 integrated film profiles NegaFix offers a unique level of control when converting negative film into positive images. Selections include film manufacturer, film type and film speed. Adjust film exposure in real time while optimizing all conversion parameters (Ai and Studio versions) for the best possible results. You can find more information on Negafix from our short guide.

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The USM dialog and its preview windows may now freely be resized and enlarged. This can be done by click dragging the lower right corner of the window. Now, a better control of the image is achieved before scanning that allows a much larger preview of the final sharpening effects.

The support of the JPEG 2000 format enables SilverFast's strongest compression to process such data 3 to 7 times faster than Photoshop. In combination with SilverFast's HiRePP function, even 3GB files may be compressed and re-opened very quickly. It is important to note that Photoshop internally calculates with 15 bit, while SilverFast uses true 16 bit!

From Version 6.4.2r4 onwards, SilverFast uses a completely new descreening in order to remove any screen dots from printed images. The newly developed descreening in SilverFast is able to detect the actual screen of the image automatically. 4 different descreening options are now available: Automatic descreening Automatic descreening (intensive) Descreening USM & Descreening "Automatic descreening" and "Automatic descreening (intensive)" are fully automated and are available without any further dialogues.

Descreening is always confronted with the challenge to find out which is the proper screen. Whenever trying to descreen in Photoshop customers will most likely cruzify image details since the available filters and Photoshop's workflow are not designed specificly for a descreening process. SilverFast's ingenious descreening uses a Fourier transformation to analyse the screen and also have the scanner select the best possible resolution for the required descreening process. Descreening will generally decrease a little bit a sharpness. To compensate for the loss of sharpness SilverFast has an option to apply Unsharp Masking simultaneously. Newspaper screen is 99 lpi / 38 lpcm Availability Studio-Versions have the new full functionality including the two full automatics. Ai, DCPro and HDR offer the complete descreening dialogue with preview, manual selection and automatic screen-detection. The fully automatic functions are not included. SEPlus offers the descreening dialogue, without preview but with manual screen input and also contains the two automatic descreening options. SE contains the new descreening, the descreening dialogue without preview, but with manual screen input. The two fully automated functions are not available.

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The storage and administration of the scanned image files are very convenient due to the possibility to add individual comments, which are stored with the picture (embedded into the picture data) according to the ITPC standard.

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PrinTao is the new professional printing function of SilverFast Ai Studio, SilverFast DCPro Studio und SilverFast HDR Studio introducing layout-functionality for images and text. For many workflow requirements using an additional layout-software will not be necessary anymore.

Take advantage of PrinTao: You are able to create your individual layouts with text and images at a high efficiency. The integration of image processing, layout functionality and printing by a single software tool is unique.