
Poor man's document camera for videoconference - lrizzo
http://info.iet.unipi.it/~luigi/document-camera/
======
montroser
In these situations where you're taking a photograph of writing or a diagram
on a piece of paper, it can be surprisingly tricky to get rid of the shading
from the lighting conditions and be left with just the content on the page in
high contrast.

This explanation nails how to do it though:
[http://www.imagemagick.org/Usage/compose/#divide](http://www.imagemagick.org/Usage/compose/#divide)

Divide a blurred copy by the original and you end up with effectively an
adaptive-normalize filter where the result is nice and clear with the shadows
and uneven lighting left behind.

Also though, there are tools like [https://miro.com](https://miro.com) and
[https://beta.plectica.com](https://beta.plectica.com) which kinda make this
obsolete for many common use cases.

~~~
duncans
I really rate Microsoft's free Office Lens for document scanning. It
automatically crops and there are a few filters you can experiment with to get
the best result and the output to PDF or whatever.

iOS: [https://apps.apple.com/gb/app/microsoft-office-lens-pdf-
scan...](https://apps.apple.com/gb/app/microsoft-office-lens-pdf-
scan/id975925059) Android:
[https://play.google.com/store/apps/details?id=com.microsoft....](https://play.google.com/store/apps/details?id=com.microsoft.office.officelens&hl=en_GB)

~~~
app4soft
For Android there are few fully free & open-source alternatives.

I use _OpenNoteScanner_.[0,1]

[0]
[https://github.com/ctodobom/OpenNoteScanner](https://github.com/ctodobom/OpenNoteScanner)

[1]
[https://github.com/yeyeto2788/OpenNoteScannerPDF](https://github.com/yeyeto2788/OpenNoteScannerPDF)

------
mhenr18
I couldn't resist trying this and making some more detailed instructions for
getting better images out of iOS. Turns out that you can get fairly good
results without any fancy software.

[https://mhenr18.github.io/improvised-document-
camera/](https://mhenr18.github.io/improvised-document-camera/)

------
Cherian
I don’t want to look like promotional, but recently a professor used an Osmo
reflector
([https://twitter.com/romps/status/1237617042338897921?s=12](https://twitter.com/romps/status/1237617042338897921?s=12))
to project class notes and it caught on with teachers.

A team worked through the weekend and released a free app to make this super
easy
([https://twitter.com/PlayOsmo/status/1241152565083090947](https://twitter.com/PlayOsmo/status/1241152565083090947)).

While the base + reflector is not free, if you already have an Osmo game at
home, you can reuse that.

~~~
jedberg
OMG, this is exactly what I needed! I've been working from home for five
years, and the one big missing piece was "whiteboarding".

I even have an extra Osmo reflector and base! Now I just have to convince the
kids to stop playing Osmo long enough so that I can use it. :)

Thank you!

------
robbrown451
When I use my phone camera to copy documents or especially photographs (i.e.
old school printed-on-paper paper photos), I've found the most useful thing is
to light it with the sun. You can do it next to a window if the sun is shining
in (best the window is clean), or I just do it on my porch if it isn't windy.
They come out with excellent quality...I have found it does better than even
scanning them (which takes much longer)

Obviously, the sun should be at enough of an angle so it won't cause glare.
You can try to position it so the sky isn't reflecting in the photo, but
honestly the effect of that is going to be miniscule because the sun is so
much brighter.

And of course, if you have to do it when the sun isn't out, you can make do
with whatever lighting you have, but the quality won't be as good from my
experience. I've done this for family photos from ages ago, and it wasn't a
problem to wait for some sunshine.

~~~
martin-adams
If you have to use indoor lighting, find a flat object to lay it on, then tilt
it parallel to the light so your hand is less likely to cast a shadow.

------
klingonopera
> _" With so many people and students around the world working from home, we
> really need some easy to deploy shared whiteboard solution. This is
> especially important for pre-college students who may not have access to
> high end hardware."_

Just add a new mode to videoconferencing, where both parties get a white
screen and both can start drawing and the resulting image stays in sync on
both clients? (I feel like this solution is so obvious, I'm about to fly out a
window - what am I missing?)

Sounds like way less work for those already developing videoconferencing apps
than to deploy stand-alone solutions in addition to that.

In fact, phones could do good just having a "scratchpad" as a "phone-variant"
of Notepad and/or Paint. It helps to quickly draw something, a simple sketch,
or communication with deaf people or those who don't share a common language.

It's sad to see the state of bloatware on phones and not seeing many useful
things. It took ages for them to add the torch/flashlight feature as a
standard into the OS, back in the day, we needed to use apps to get that done,
so I think it's probably symptomatic of the entire industry.

Hell, it's no wonder Apple can get away selling their expensive _stuff_ , the
others aren't really setting the bar high enough...

~~~
lrizzo
>> "With so many people and students around the world working from home, we
really need some easy to deploy shared whiteboard solution. This is especially
important for pre-college students who may not have access to high end
hardware." >Just add a new mode to videoconferencing, where both parties get a
white screen and both can start drawing and the resulting image stays in sync
on both clients? (I feel like this solution is so obvious, I'm about to fly
out a window - what am I missing?)

Author here.

There have been a few proposals in this space for the past 25 years including
hangouts extensions, using a virtual camera that just exports the screen (if
people remember the old mbone tools wb and vic; I myself wrote an extension to
replace the camera with a snapshot from a configurable region of the X
screen), and my own shared whiteboard which gives parties a shared screen that
they can edit modify replay ...

[http://info.iet.unipi.it/~luigi/wb/](http://info.iet.unipi.it/~luigi/wb/)

There are two main reasons (in my opinion) why this space has been neglected:

\- almost nothing matches the convenience, speed and _resolution_ of writing
and drawing with an actual pen. Pads with sufficient resolution and decent lag
are only appearing now, and they are fragile and expensive. Graphic tablets
are cheap but lack the visual feedback and looking at the output on the screen
still has significant latency. They are moderately usable, but takes time to
get used to them, and you need a real 10+in screen to use them effectively.
Using a finger or a conductive pen on a phone screen is only good for small
sketches, not for writing longer sentences or formulas.

\- the main users of such products would be non commercial entities (pre-
college schools, students) so there are no paying customers. Even at college
level lectures are increasingly based on slides prepared in advance.
Businesses, of course, use slides or meet in person, and the whiteboard style
of collaboration is generally done in person.

Social distancing now may actually create more use cases and perhaps returns
(in terms of actual money or social appreciation) that stimulate software
solutions to appear.

The Apollo13 problem still stands: even if we had good and cheap technology
for writing, at this time it would be impossible to build and sell such
products to customers, so we have to find solutions that use hardware already
in possession of the users.

~~~
klingonopera
> _" almost nothing matches the convenience, speed and _resolution_ of writing
> and drawing with an actual pen"_

Absolutely agree, which is why I think attempting to reproduce that
convenience on a digital system would be the wrong assumption to begin with.
Pen and paper are special.

I think the issues you described in combination to the original solution I
mentioned could be mitigated by dynamically increasing the image size. So
instead of viewing the screen as your entire whiteboard, it grows as you add
more drawings/notes to it. So for example, you have the phone and the white
drawing board screen, you scribble _f(x) =_ on the _entire_ horizontal surface
(thus circumventing the inherently low resolution issue of most touch-screens)
and then the image width doubles and shifts your view to the newly created
whitespace, and so on.

It's not a perfect solution, but I think it could and believe it would lead to
the same desired results. It's a compromise between human convenience and
adaptation to (pre-existing) physical machine restrictions.

On the topic of financing... maybe crowdfunding, then?

------
Hnrobert42
Off topic, but as OP is from the .it TLD, it’s interesting to note OP prefers
riga pasta, especially in light of this article:
[https://qz.com/1811768/coronavirus-lockdown-ignites-an-
old-i...](https://qz.com/1811768/coronavirus-lockdown-ignites-an-old-italian-
debate-its-about-pasta-of-course/)

~~~
martopix
(unipi.it: University of Pisa)

~~~
martopix
Also, smooth pasta is embarassing.

~~~
stclaus
that's why they're using it for something else than meals :)

------
mkl
A stack of books with a couple of rulers under the top one works better - it's
height-adjustable.

Moving a bit further up the quality ladder, I've just built myself a solid
laptop/monitor stand out of plywood, and I'm going to attach a strut sticking
out the back to hold up a webcam-as-document-camera and (when it arrives) an
LED ring light.

There are actually a whole lot of cheap products based around the phone-as-
document-camera idea, e.g.
[https://www.aliexpress.com/item/4000309823825.html](https://www.aliexpress.com/item/4000309823825.html),
a stand, phone holder, and ring light.

------
exikyut
> _frame rate, encoder quality. Especially low end phones do not have enough
> power to encode highly variable input (see previous bullet), resulting in
> unreadable images. An encoder setting for low frame rate (e.g. 1-2FPS) and
> high quality would be invaluable for such an use case._

Ways to go even better:

\- Don't use an "<x>FPS" based model of continuous transmission - the paper
isn't always updating by default

\- In extremely low-bandwidth situations, never update while there's a hand in
the frame; only update once the paper image settles again

\- Get all fancy with feature detection and draw buttons on the corner of the
paper; one of these could be "update" and the device would beep to acknowledge
the frame had changed. This is actually practical as not everyone has
bluetooth keyboards, audio-based commands would be distracting, and tapping
onscreen buttons would nudge the device

\- Perform frame border analysis and automatically crop and rotate the actual
paper as it's moved around

------
kohtatsu
Re. orientation: the phone shouldn't be trying to determine landscape/portrait
when flat; it should gracefully keep the previous state for _at least_ a dozen
degrees.

On my 11 Pro it doesn't change until ~40 degrees of attitude.

~~~
ckdarby
In Android there's an option to lock orientation.

~~~
lrizzo
I believe it is either "force portrait" or "autorotate", there is no "force
landscape".

~~~
def8cefe
You flip it landscape and turn off autorotation.

~~~
sjagoe
When my phone was updated to Android 9, that toggle became force-portrait. If
I enable it now, it immediately turns back to portrait and disables rotation.

~~~
def8cefe
I'm on AOSP Android 10 and it works as I described. Can't remember the
behaviour on 9. Have a good one.

------
wallflower
If you want to upgrade from DIY, Ipevo sells a line of document cameras that
start at $99. Some are not as expensive as dedicated, stand alone classroom
document cameras because they require a computer to operate.

[https://www.ipevo.com/products](https://www.ipevo.com/products)

------
sandreas
Thank you HN for this article and the comments.

Years ago I wrote a little java command line tool based on BoofCV (Pure Java
CV lib - [https://boofcv.org/](https://boofcv.org/)), tess4j (tesseract) and
PDFBox to create PDFs with OCR and invisible Text Layer, to make its contents
searchable like the OCR Option in PDF X Change Viewer.

I used a combination of Thresholding and deskewing to improve my Documents
(e.g. Sauvola, Nick) - see
[https://boofcv.org/index.php?title=Example_Thresholding](https://boofcv.org/index.php?title=Example_Thresholding)

Now I plan to restore and improve the old code and provide it as open source
solution :-) Hope the code still somewhere on my old harddisks.

------
kernelsanderz
Reminds me a kickstarter project I backed years ago called ScanBox. I still
pull it out from time to time to scan documents when traveling, and have used
it once or twice for a live document scanner, though the sides of the box make
it difficult to get your hand into.

These days our team either uses the built-in whiteboard functionality in Zoom,
or jump into a Google Drawing or Slides document for the live collaboration.

Sometimes I'll also use Zoom's AirPlay functionality to share my iPad screen
and use an app like Notability to share. Though that's only one-way and not
collabarative.

~~~
seltzered_
Had to look this up, neat:
[https://www.kickstarter.com/projects/limemouse/scanbox-
turn-...](https://www.kickstarter.com/projects/limemouse/scanbox-turn-your-
smartphone-into-a-portable-scann/description)

Bonus points if someone can sell this feature within a notebook/tablet stand.
Modifying a tiny tower stand
([https://tinytowerstand.com/](https://tinytowerstand.com/)) comes to mind.

~~~
tpetry
That‘s a really cool idea, does not need much space when not used :)

------
zvonimirs
Hi guys, founder of AWW ([https://awwapp.com](https://awwapp.com)) here. AWW
is one of the first and simplest online whiteboard on the market. Check us
out. Also, for schools, we are giving free premium until the end of the
COVID-19 situation. Stay safe everyone.

------
bitfhacker
I use a pile of book with the mobile phone on the top of them. For photos I
use CamScanner free because it crops automatically the photo, auto contrast
them and save multiple pages as a pdf.

------
Aardwolf
"Apollo 13 style camera stand"

That name sounds amazing for being a box of pasta!

------
timtas
Fine until you eat up all your other pasta. Then where are you? Well, I guess
at that point you have bigger problems. :)

------
trevyn
Just cut a slit the shape of the cardboard profile in the top of the pasta box
and shove the cardboard in?

~~~
zaroth
You would still need to fill the box with something heavier than pasta.

------
shemnon42
What's more valuable: The box of pasta or the roll of coins providing a
counterweight?

~~~
kernelsanderz
That's what I thought. Surely you could buy 10 professional document cameras
for the value of that pasta! :-)

~~~
ddsea
At least this design doesn't need TP.

~~~
applecrazy
Never in my life would I have imagined that toilet paper is rarer and more
valuable than boxed pasta.

