Video capture at scanner resolution via Linux laptop

September 21, 2018 9:43 AM

Looking for a way to view/magnify objects, books and documents with fine print up-close like a scanner, but via video capture such as a hand-held USB camera. Degree of difficulty Linux, VLC, no phone or onboard-laptop cameras.

Live viewing is the goal; screen capture is secondary. Think like you are scanning the Scoop probe for the Andromeda Strain, just not at microscopic levels and for text rather than green goo.

I have unsuccessfully used multiple magnifying glasses and clip-on lenses with a Logitech camera model used by several remote participants on webcasts like TWiT. The USB camera is crisp and clear for talking heads and room views, just blurry with small text like, say, soup can or vitamin bottle ingredient lists and similar fine print.

Platform is VLC video capture software on Xubuntu 16.04 LTS. USB 2 and 3 Type-A jacks, USB-C not available. I can magnify what I get from the vidcap device within VLC and XFCE desktop environment.

Traditional still-photo scanners, smartphones or laptop on-board cameras are not available to me. Windows- and Mac-based solutions are not available to me.

Cheaper is better - I suspect a high-end DSLR with live video and USB connection would work, but my budget is limited to non-battery-gorging consumer-grade USB cams (like the one I have) and clip-on lenses.

posted by zaixfeep to Computers & Internet (7 answers total)

Have you considered a USB microscope? They're around the US$30 mark. They don't have the greatest resolution (2 - 5 mp still, 720p streaming) but the ones I've used work fine with the Linux video subsystem. They're manual magnification, manual focus and usually have an LED halo light of adjustable brightness. Sure, they'll be fiddly to set focus and magnification, but the plus is they won't try to hunt for focus on something you don't want to see.

Example photo from a cheapo roughly 5 year old USB microscope: each of these cells are 3.8 mm across … (self link to show results, captured as a still using Cheese under Ubuntu)

Two issues you might want to deal with:

1. The standard desktop mount allows a dismal range of adjustment. If you can put together a better stand (or buy one: they'll add maybe another $30 to the kit) your viewers will thank you.
2. I don't think these stream sound

posted by scruss at 10:28 AM on September 21, 2018 [3 favorites]

Look at the USB endoscope cameras, 20-30 range should work for small text.
posted by sammyo at 10:57 AM on September 21, 2018 [2 favorites]

Seconding endoscope, they also work great for essentially macro close-up videography. Mine has a little WiFi that will stream to several devices at once, but other models go straight to your Linux pc.
posted by SaltySalticid at 11:13 AM on September 21, 2018

If you're willing to void a warranty, you can adjust the focus length on many Logitech webcams. There are videos on Youtube that'll walk you through it. You'll need a set of small screwdrivers.
posted by dws at 11:51 AM on September 21, 2018

Response by poster: All answers here have merit, I thank each of you.

Would never have guessed endoscopes were available to consumers. I assume they are not medical grade, because please $DEITY don't let self-colonoscopies be a thing,
posted by zaixfeep at 4:14 PM on September 22, 2018

Response by poster: UPDATE: Amazon's USB microscopes and some endoscopes are mostly the same generic model about the size of a big Snickers bar with an 8-LED halo light and min 40x mag. At min magnification, I , and hold the camera within an inch 0f the text get 1/2 character filling up the whole screen, and despite the mag, it's still a bit fuzzy like consumer cameras - better for non-character-based viewing.

I found the proper category by accident: "USB Document Camera" - it's what has replaced overhead and opaque projectors in classrooms. I've ordered one and will report once I've evaluated it.
posted by zaixfeep at 5:11 PM on October 24, 2018

Best answer: UPDATE: Ipevo CDVU-03IP Point 2 View USB Camera (2MP) appears adequate. 5MP was out of stock, but would probably be even better. Use onboard buttons for auto-focus adjustment.
posted by zaixfeep at 10:10 AM on October 29, 2018