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I'd like to scan some photos with a 48-bit color depth in macOS Tahoe. My scanner is a Canon LiDE 400. It claims to support "scanning mode" of "48-bit Internal / 48-bit or 24-bit External". But I can't seem to find any settings to control the color depth of the scanned photos.

If I use Image Capture, all it gives me is "Kind": "Color", "Black & White", or "Text"; and a variety of resolutions from 75 dpi to 4800 dpi. Googling, I see some references to an option to choose "Millions" or "Billions" of colors, but I don't see that anywhere. I'm unsure whether the option just doesn't exist in Tahoe, or if its absence indicates a problem with my scanner.

Which of these is the most likely explanation?

  • Image Capture (along with the whole macOS-native scanning pipeline) just doesn't do 48-bit color, I'm going to need different software

  • The option should pop up when supported, but I'm using a generic driver that doesn't support it (how do I fix this? Canon provides a utility that wasn't any help)

  • Despite the advertised specs, this scanner is just not capable of 48-bit output, and if I had a different scanner, it would work

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2 Answers 2

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First of all, see if there is ICE (Image Capture Extension) software for your scanner. This is usually found in /Library/Image Capture/Devices/. This is what provides device-specific support in Image Capture.

Canon does provide reasonably up-to-date software for the scanner. If it doesn't work, you should contact them for support.

I can select "Billions" in Image Capture for my scanner here:

Image Capture controls

Doing this creates a PNG file, which Affinity Photo reports as RGB/16, e.g. 16 bits per channel. (48-bit).

Of course, 48-bit is far and away more accuracy than the source material will yield, or that your eyes can see.

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I tracked down this disclaimer in the manual: 48-bit scanning is Windows-only.

enter image description here

However, thanks to the comments below: I've confirmed VueScan is able to produce 48-bit TIFF scans on macOS. (I had tried it and couldn't find the setting, but failed to notice the very important "Options: Standard" vs. "Options: Professional" on the "Input" tab. Got to switch to "Professional" to unlock 48-bit options: "Input -> Bits Per Pixel" and "Output -> TIFF file type".)

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  • That sounds driver-specific. You might try Vuescan, which usually doesn't need the manufacturer's driver. Commented Feb 25 at 19:34
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    VueScan has a page explicitly on the LiDE 400 hamrick.com/vuescan/canon_lide_400.html (scroll down to the bottom). It doesn't explicitly say 16-bit scanning, but as @MarcWilson says it is the most likely way to do what you need. Commented Feb 25 at 22:20
  • The latest changelog from VueScan says "Added support for saving 48-bit RGB when using 24-bit RGB scanners", which seems counterproductive, but someone must have wanted the feature. Commented yesterday

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