Digitization using Epson scanners
There are three software packages supporting Epson scanners: Epson Scan, Silverfast and Vuescan. In order to digitize infrared channel it is necessary to save to RAW files. These are not supported by Epson scan. Moreover Silverfast does not seem to allow to configure scanner's exposure, which plays important role for additive color screen processes due to their natural darkness and high dynamic range.
We thus strongly recommend Vuescan, which is capable of saving RAW files and is relatively cheap to purchase.
First switch to the more option modes. Then the following options should appear in the Input tab:
Configure them as follows
- Mode: Transparency configures scanner to scan in the narrower area with focus slightly above the glass bed. This is the only possible setting for digitizing including infrared channel. Transparency 8x10 configures scanner to scan wider area (almost whole scanning bed) but has no support for infrared channel. In this setting the scanner is focused approximately to the glass bed and is good for scanning glass plate negatives with emulsion facing down.
- Media: Either slide film for transparencies or B/W Negative for negatives. This affects the way Vuescan choses exposure time so it is not good idea to scan negatives as slides or vice versa. Color negative also adjusts the analog gain for orange mask of modern negatives which is not a good idea.
- Bits per pixel: Either 64 bit RGBI for scanning with infrared or 48 bit RGB for scanning without.
- Preview Resolution: Probably best set to default. Setting it too low will make preview faster, but also reduce autoexposure quality.
- Scan resolution: 1600 for Transparency or 2400 for Transparency 8x10
- Skew: Please keep it to 0. Rotating image breaks the geometry and makes it harder to fix it later.
- Auto Save: I find it useful to set it to Scan.
- Lock exposure: Keep it disabled unless you need to adjust exposure manually as discussed below.
- Analog Gain: Set all gains to 1.
Lock exposure feature is on the end of the Input tab
Important settings here are Buffer and Border. It is good idea to scan originals including the corners and tape, but it is important to calculate exposure only using the healthy part of image. Border increase size of scanner area over one visible in crop box by given percentage. Buffer reduces the size of selected area used to analyze exposure. I usually select the image area and set Border to be large enough to get the matting tape scanner. I also set small buffer to reduce errors.
It is important to disable infrared clean setting. This affect the infrared exposure time. Other setting here are not important since we are going to saw raw files.
Most of settings here are not relevant since we are going to save RAW file.
Here enable Raw file and set Raw file type to match mode in Input tab (64 bit RGBI for scanning with infrared or 48 bit RGB for scanning without). Leave Raw save film disabled.
It is possible to enable live histogram by setting Graph type to RAW and Histogram type to Linear.
Be sure to do Preview for every slide after the vuescan was correctly configured, so exposure times are computed correctly. Then pressing Scan should give an output file.
Scanning then takes two passes. First pass is RGB. The live display should show somewhat dark image (due to linear gamma) but with reasonable contrast. Then the second pass will be infrared, which will show black and white preview. Once done final scan will appear
