This Appendix reviews and summarizes the strengths and weaknesses of five widely available scanning programs—VueScan, SilverFast, Nikon Scan, Epson Scan, and Canon ScanGear. The Guidance on Using Scanning Software at http://archivehistory.jeksite.com/chapters/scan_part1.htm provides detailed information on using each of these programs to create archival master images consistent with the criteria described in Chapter 2.
As discussed in Chapters 2 and 3, major adjustments of tone and color should be done with a bit depth of 16 bits per channel because historical photographs and documents are often significantly faded. These adjustments can be done with the scanning software or later with image-editing software. Either way, the scanning software needs to be operating at 16 bits per channel, or as close to 16 bits as a scanner can perform.
This Appendix first discusses each of the scanning programs and then discusses which programs can be used effectively for different scanning workflows. The workflows have differing degrees of use of scanning software and image-editing software.
The features and ease of use of scanning software varies greatly. The methods and workflow that work well for one scanning program often will not work well with another. Scanning software can be designed for different primary purposes. Some scanning software focuses more on making images for printing or the internet rather than for archives. Scanning software is provided by third party companies as well as by the companies that manufacture scanners.
VueScan is a third party scanning program that places high priority on capturing the full information in a scanned image. VueScan is the only scanning software described in this Appendix that reports the percent of pixels being clipped by histogram adjustments and can display pixels that are clipped and pixels that are out of gamut. Also, the adjustments to tone and color can be made after the final high-resolution scan has been done. This allows the original item to be removed from the scanner and used for direct comparison while the adjustments are made. A related workflow that is usually appropriate and highly efficient for scanning documents requires scanning items only once rather than the usual two-step practice of making separate preview and high-resolution scans. The adjustments with VueScan tend to be milder than for other scanning software. Overall, VueScan preserves the original image information but assumes that further processing will be done with image-editing software. These priorities fit well for most archival scanning projects. Professional and Standard versions of VueScan are available.
VueScan can be used with virtually any scanner and multiple scanners can be used with the license for one copy of the program. The same workflow and controls can be used with different models and brands of scanners. The scanning controls are relatively simple to use and are based more on numeric fields than on graphical displays. After years of working with other programs, I have come to use VueScan for most of my scanning activities (with the exception of my Nikon film scanner). If I would have used VueScan from the beginning of my work with historical items I would have saved a large amount of time over the years and produced better results.
The professional version of VueScan includes options for assigning profiles for the working color space, the monitor, and the scanner. The standard version of VueScan does not have these options. The standard version uses sRGB as the working color space and also uses a generic sRGB color profile for the monitor profile. The inability to use a more optimal profile for the monitor is a significant disadvantage for archival work with the standard version of VueScan.
The professional version of VueScan can apply custom scanner profiles, but only profiles made with VueScan. If a scanner profile made with other software is assigned, the default “Built-in” profile that comes with VueScan is used and there is no warning message that the assigned profile is not used. VueScan creates matrix profiles for a scanner. Both the professional and standard versions of VueScan can embed the profile for the selected working color space in the output files; however, the standard version has sRGB as the only option for working color space. VueScan does not write the EXIF field for color space to output files.
SilverFast is a frequently recommended third party scanning program that focuses on preparing an image for printing rather than for archiving. SilverFast has many complex interacting options that are difficult to understand and are not well documented. A different version of SilverFast is required for each model and brand of scanner. In addition, there are several different versions of SilverFast with different features and purposes (e.g., Silverfast SE, SE Plus, Ai, Ai Studio, DC VLT, DC Pro, DC Pro Studio, DC SE, HDR, and HDR Studio). The company does not attempt to develop detailed documentation for each of the versions. I find the lack of specific documentation to be a major handicap when attempting to work with SilverFast.
With proper settings SilverFast can produce archival images, but some users may find that the complexity prevents a sense of confidence and reliability when using the software. I have spent much time working with SilverFast software, manuals, and videos with two different scanners but am not confident that I correctly understand the operation of some of the complex interacting options. Others may feel confident that they fully understand the options.
Because SilverFast does not display clipped pixels when making tone and color adjustments, final tone and color adjustments may sometimes be done more efficiently and reliably with image-editing software that handles clipping more precisely. Also, many of the features intended for printing add complexity and cost that are not useful for archival scanning. The requirement to purchase a different version of SilverFast for each model of scanner can be expensive.
The different versions of SilverFast have different color management features. For the SilverFast Ai version that came with an Epson V750 scanner, the color profile that is embedded in the output file may be the profile for the printer or another profile rather than the profile for the working color space. The profile that is embedded depends on the interaction of settings in several different configuration fields and unexpected results can easily occur. The embedded profile can change even when the color management settings are not changed. The settings that seem intuitively obvious result in the printer profile being embedded in an output file. The settings that allow the profile for the working color space to be embedded in the output file apparently turn off color management for printing. These interacting options (and others) are described in more detail in the Guidance for Using Scanning Software at http://archivehistory.jeksite.com/chapters/scan_part1.htm.
Certain versions of SilverFast can create profiles for a scanner. The profile that SilverFast created for my Epson V750 scanner included lookup tables for perceptual and colorimetric rendering intents as well as a matrix. However, images created with perceptual and relative colorimetric rendering intents were not different when evaluated with the methods for comparing rendering intents described in Appendix A. When a custom scanner profile created with different software was used with SilverFast, a comparison of images with perceptual and relative colorimetric rendering intents did find the expected differences. SilverFast does not write the EXIF field for color space to output files.
Nikon Scan is the software provided by the Nikon company for their professional level film scanners. My experience has been Nikon Scan is the optimal software for use with Nikon scanners. For example, grain in the output image is a significant issue with the sharp scans of 35 mm film with a Nikon scanner. The grain reduction methods in Nikon Scan match Nikon scanners very well. Nikon Scan makes effective tone and color adjustments. In general, Nikon Scan is easy to use and very nicely documented.
Unfortunately Nikon has stopped manufacturing and supporting film scanners, but the scanners are still widely used. Although Nikon has not upgraded Nikon Scan for use with Windows 7, modified drivers have been developed and are freely available at various places on the internet. Following such guidance I was able to install and use Nikon Scan with a Windows 7 64-bit system with no problems.
Nikon Scan comes with its own scanner profiles that work well in most circumstances. However, some users report that their scanners tend to produce noticeable color casts. Nikon Scan does not create custom scanner profiles or have specific settings for using custom profiles; however, it is relatively easy to use a custom profile by replacing the Nikon profile files. The scanning guidance document at http://archivehistory.jeksite.com/chapters/scan_part1.htm describes how to do that.
Nikon Scan embeds the profile for the working color space in the output file when color management is turned on. However, the embedded profiles are called “Nikon Adobe RGB 126.96.36.19900” and “Nikon sRGB 188.8.131.5201” rather than Adobe RGB and sRGB. Some users and image-processing software may not recognize these as standard color spaces. The situation is further confused by the fact that Nikon Scan sets the EXIF color space field to sRGB even when the working color space is Adobe RGB. The best practice when using Nikon Scan is to use image-editing software to set the embedded profile and EXIF field to standard values.
Epson Scan is the basic software provided with Epson scanners. It has simple controls that must be set manually for each item for archival scanning. It can provide acceptable results for archival scanning but is inefficient and less reliable to use due to the minimal capabilities to automatically apply settings and to store and reuse settings. Also, the resolution of the histogram is low, which makes adjustments less reliable. Epson Scan can be used efficiently in a workflow where most adjustments are made in a later step with image-editing software.
Epson Scan can use a custom scanner profile that is created by other software, but does not include methods for creating a custom scanner profile. Epson Scan has an option to embed the profile for the working color space in the output file. It does not write the EXIF color space field or any other EXIF documentation to the output files.
Canon ScanGear is the software that comes with Canon scanners. It has significant limitations. When color management is used with ScanGear, the options for making adjustments to tone and color are turned off and the profile for the working color space is not embedded in the output file. The documentation for ScanGear is ambiguous about when scanning and processing are done with 8 bits per channel versus with 16 bits per channel. After pursuing this question with Canon support and obtaining responses from three different people, it appears that the only way to be certain that scanning and processing are done with 16 bits per channel is to make the output file 16 bits per channel (16 bit grayscale or 48 bit color). A further inconvenience is that the total number of pixels on each side of the selected image is not displayed and a calculator or the tables in Chapter 2 are needed to set the appropriate scanning resolution.
Despite these limitations, ScanGear could be used for archival scanning if the output files have 16 bits per channel and assignment of working color space and adjustments are handled with image-editing software.
ScanGear does not embed a profile for working color space in the output files and does not write the EXIF color space field or any other EXIF documentation to output files. Information about the working color space must be assigned by image-editing software.
Chapter 3 noted three different workflows for archival scanning. These differ by the amount of processing done with image-editing software after scanning. These options and their applicability with the different scanning programs are described below.
Workflow A. Most Adjustments with Image-editing software
With this workflow scanning software is used to create output files with 16 bits per channel and minimal adjustments for tone and color. Image-editing software is used to make adjustments and to output the final master images, which may be either 16 or 8 bits per channel.
All of the scanning software described in this Appendix can be used with this workflow. The simplest programs such as Epson Scan or Canon ScanGear may be efficient to use because of the absence of unnecessary complicating options.
Professional level image-editing software such as Photoshop CS is optimal for this workflow because of the need to process images with 16 bits per channel and possibly assign a custom scanner profile to the input image. As described in Chapter 3 the consumer level program Photoshop Elements can also be used but is less efficient and less reliable because basic tone and color adjustments at 16 bits per channel must be applied directly to the image rather than with layers. Also, Photoshop Elements cannot assign a custom scanner profile to the input image.
Workflow B. Refinements with Image-editing software
With this workflow scanning software is used to make the major adjustments to tone and color with 16 bits per channel and to create output files with 8 bits per channel. Image-editing software is used to make refinements and to output the final master images. This workflow may be more appropriate with Photoshop Elements because the final refinements can be done with layers with 8 bits per channel.
VueScan, Nikon Scan, and SilverFast can be used with this workflow. Epson Scan could be used with this workflow for small projects but the effort to make the needed careful manual adjustments for every image would quickly become burdensome. Workflow A above, even when using Photoshop Elements, may be preferable with Epson Scan. Workflow A may also be optimal with SilverFast for those who are not confident in managing the complex options.
This workflow could be enhanced by making the scanned images 16 bits per channel for cases when more extensive adjustments are needed with the image-editing software.
Workflow C. Image-editing software not Used for Master Images
Attempting to create archival master images without using image-editing software would require significant compromises at present, but may be appropriate in some situations. None of the scanning software reviewed here completely and correctly writes working color space information to the output file as recommended for best practice in Chapter 2 and Appendix A. Image-editing software such as Photoshop Elements and Photoshop CS do write the recommended information correctly. The scanning programs embed color profiles that meet the criteria for good practices.
When tone and color are adjusted to match a reference target included in the image, Nikon Scan, SilverFast, and Epson Scan have the basic eyedropper and histogram tools needed to make the tone and color adjustments. Using image-editing software to set the color space information in the output file is still recommended for best practice. VueScan and Canon ScanGear do not have the needed eyedropper tools so the adjustments must be made with image-editing software.
When tone and color are adjusted to correct fading and exposure, Nikon Scan can create output images that usually require little or no additional adjustments when the original item is a color slide or negative. Tone and color adjustments are handled well with Nikon Scan. Interference from defects can be minimized for color images by applying infrared dust and scratch correction prior to making tone and color adjustment. However, infrared dust and scratch correction cannot be used with most black and white film and final tone adjustments often can be done more precisely and reliably with image-editing software. Unfortunately, the working color space information in the output files is particularly problematic with Nikon Scan and needs to be set with image-editing software.
VueScan is designed with the assumption that final refinements will be done with image-editing software. VueScan provides the most precise and useful tracking of clipping and can apply infrared dust and scratch correction before adjusting tone and color; however, color adjustments often need additional refinement. Also, the values of the darkest and lightest tones in the output image cannot be precisely specified. These adjustments can be easily and precisely achieved with image-editing software.
The version of SilverFast that I have been using does not have an option to display clipped pixels and does not apply infrared dust and scratch corrections before setting histogram adjustments. Given these limitations, final tone and color adjustments with the histogram can often be done more precisely and reliably with image-editing software. SilverFast comes in many different versions. Other versions may not have these limitations; however, the documentation does not describe internal operations such as exactly when infrared dust and scratch correction is applied.
Epson Scan provides simple basic manual scanning controls that do not handle clipping as precisely and reliably as would be optimal for archival scanning. The poor resolution of the histogram displays contributes to the lack of precision. Here too, the safest practice is to handle tone and color adjustments conservatively and make final adjustments with the more precise, reliable capabilities of image-editing software.
Canon ScanGear does not allow tone and color adjustments when a working color space is specified and does not write information about the working color space to the output file. Use of image-editing software is essential if ScanGear is used for archival scanning.
Creating master images without using image-editing software may be needed when time or image editing capabilities are limited. When possible, the safest practice would be to be to scan conservatively and refine the images later.
[Version of 12/29/2013]
Chapters in the Book
B. Overview of Scanning Software
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