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'[TECH] Whiteboarding example'
2009\03\02@180724 by Vitaliy

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I finally have an example that I can freely share. :)

We start by taking a picture of the whiteboard with a cheap digital camera:

http://maksimov.org/piclist/whiteboarding/original_image.jpg

We open it in Microsoft Photo Editor, crank up contrast and brightness, and
get this:

http://maksimov.org/piclist/whiteboarding/StnTimers.pdf

Normally, the image would be sent directly to the printer, instead of the
PDF converter.

Voila, we now have a faximile of the board -- in under three minutes:

http://maksimov.org/piclist/whiteboarding/board_copy.jpg

This works with color markers too, and usually the drawings are more
complicated (result of an hour-long brainstorming session, for example).

Vitaliy

P.S. "Whiteboarding" -- sounds like something the CIA would do to the
terrorists, doesn't it? :)

2009\03\02@181744 by cdb

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One of your felt tips is facing the wrong way :)

Colin
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2009\03\02@183342 by Stephen D. Barnes

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cdb wrote:
> One of your felt tips is facing the wrong way :)
>
> Colin
> --
> cdb, .....colinKILLspamspam@spam@btech-online.co.uk on 3/03/2009
>  
> Web presence: http://www.btech-online.co.uk  
>  
> Hosted by:  http://www.1and1.co.uk/?k_id=7988359
>  
>
>  
Actually two are facing in the opposite direction from the others. Who
is to say which are facing the wrog way? ;-)

--
Regards,
Stephen D. Barnes

2009\03\02@183707 by Vitaliy

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cdb wrote:
> One of your felt tips is facing the wrong way :)

Two, actually. :)

2009\03\02@184101 by Vitaliy

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Stephen D. Barnes wrote:
>> One of your felt tips is facing the wrong way :)
>>
>>  
> Actually two are facing in the opposite direction from the others. Who
> is to say which are facing the wrog way? ;-)

Good point.

Keep the contructive feedback coming!

;-)))


2009\03\02@194404 by Michael Algernon

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>
>
> Vitaliy
>
> P.S. "Whiteboarding" -- sounds like something the CIA would do to the
> terrorists, doesn't it? :)


What does that make blackboarding ?
MA



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All ideas, text, drawings and audio , that are originated by WFT  
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2009\03\02@200356 by cdb

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:: What does that make blackboarding ?

A residential school for funereal assistants, or is that
mortarboarding?

Colin
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2009\03\02@200933 by Roger, in Bangkok

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Something that code pirates do ...
RiB

On Tue, Mar 3, 2009 at 7:44 AM, Michael Algernon <.....picKILLspamspam.....nope9.com> wrote:

{Quote hidden}

> -

2009\03\02@201125 by Roger, in Bangkok

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Naw, that's building a brick house ... or the little brick house behind the
big house.

On Tue, Mar 3, 2009 at 8:03 AM, cdb <EraseMEcolinspam_OUTspamTakeThisOuTbtech-online.co.uk> wrote:

>
>
> ...
> A residential school for funereal assistants, or is that
> mortarboarding?
>
> Colin
>

2009\03\02@211610 by Sean Breheny

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Hi Vitaliy,

It looks great, although I don't really understand all the steps. Why
wasn't the original photo good enough?

Sean


On Mon, Mar 2, 2009 at 6:06 PM, Vitaliy <spamspamspam_OUTmaksimov.org> wrote:
{Quote hidden}

> -

2009\03\02@214331 by Vitaliy

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Sean Breheny
> It looks great, although I don't really understand all the steps. Why
> wasn't the original photo good enough?

I'm glad you ask! :)

- It is more difficult to read when printed (extra stuff, gray background).
- It wastes printer toner.
- It makes it difficult to add notes to the paper version.
- You can't fax it, or convert into 1-bit color PDF, and be sure of the
outcome.

Cropping and cranking up brightness/contrast literally takes only a few
seconds, so there's very little extra effort involved in making it
printer-friendly.

Saving whiteboard scribbles this way, is a great time saver. Olin mentioned
that he uses a tripod, and takes pictures of the notes and the empty
whiteboard, and then subtracts the two to get the actual text.

The point of this exercise was to show that it is possible to take one
picture without a tripod, and get it to look like handwritten text on a page
very easily and inexpensively. Usually we just leave the camera in the
meeting room, and take pictures of whatever was on the board, before erasing
it.

Vitaliy

2009\03\03@005945 by Neil Cherry

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cdb wrote:
>
> :: What does that make blackboarding ?
>
> A residential school for funereal assistants, or is that
> mortarboarding?

I thought mortarboarding was what they did at the gunnery range?

--
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2009\03\03@071606 by olin piclist

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Vitaliy wrote:
> Saving whiteboard scribbles this way, is a great time saver. Olin
> mentioned that he uses a tripod, and takes pictures of the notes and
> the empty whiteboard, and then subtracts the two to get the actual
> text.
>
> The point of this exercise was to show that it is possible to take one
> picture without a tripod, and get it to look like handwritten text on
> a page very easily and inexpensively.

That method is easier, but may not work as well depending on factors like
the evenness of the lighting.  Your method worked very well in the example.

I note that you used black marker.  I find black marker is more difficult to
erase than the colored ones, so I no longer even leave black markers by the
whiteboard.  While your method should be able to get colors to work, the
range of offset and gain to make them look right will be more narrow,
possibly compromising the background or cutting into text in some areas.
Everything is a tradeoff.  Use whatever works for you.


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2009\03\03@075524 by Sean Breheny

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Got it. Thanks for the explanation :)

Sean


On Mon, Mar 2, 2009 at 9:42 PM, Vitaliy <KILLspamspamKILLspamspammaksimov.org> wrote:
{Quote hidden}

> -

2009\03\03@082954 by Philip Pemberton

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Vitaliy wrote:
> We start by taking a picture of the whiteboard with a cheap digital camera:
(snip explanation)
> Voila, we now have a faximile of the board -- in under three minutes:

I never did find the little Delphi app I wrote to do whiteboard image
enhancement... so I've been rewriting it in C++ using the CImg image
processing library.

At the moment, it does basic contrast enhancement, based on a partial
implementation of an algorithm I found in a research paper (Zhang, Z. and He,
L. "Whiteboard scanning and image enhancement," _Digital_Signal_Processing_ 17
(2007) pp.414-432). I've also got a partial implementation of a Hough
transform edge detector, which attempts to detect the corners of the
whiteboard, and then applies a perspective correction to straighten it.

The image enhancement algorithm splits the photo into squares of 15x15 pixels
in size, then takes all the pixels in that area and sorts them by luminance.
The top 25% of those values are averaged together to produce an "average
colour" value, which is then applied to the image (division operator on each
colour channel) to remove the background.

Catch is, it falls over when a square is completely filled with ink.
"Something divided by zero, AARGH, fail!"

I think I need to rig up a plane-fitting algorithm to convert the reference
image into a set of values to plug into the equation:
  z = A*x + B*y + C

Unfortunately, I've yet to find a decently well-written explanation of how one
goes about doing such things on computers... :(

> P.S. "Whiteboarding" -- sounds like something the CIA would do to the
> terrorists, doesn't it? :)

Don't encourage them :)

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2009\03\03@090921 by Alan B. Pearce

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> P.S. "Whiteboarding" -- sounds like something the CIA would do to the
> terrorists, doesn't it? :)

I thought you do that off the beaches of Hawaii ... ;)))

2009\03\03@142441 by Vitaliy

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Olin Lathrop wrote:
>> Saving whiteboard scribbles this way, is a great time saver. Olin
>> mentioned that he uses a tripod, and takes pictures of the notes and
>> the empty whiteboard, and then subtracts the two to get the actual
>> text.
>>
>> The point of this exercise was to show that it is possible to take one
>> picture without a tripod, and get it to look like handwritten text on
>> a page very easily and inexpensively.
>
> That method is easier, but may not work as well depending on factors like
> the evenness of the lighting.  Your method worked very well in the
> example.

Yes, evenness of the lighting is critical. Reflective properties of the
board, too: the one in the example is very white. We have another one that
looks yellowish, and is not as good for picture taking. Ironically, the
extra-white board was about 1/4 the cost (it is also slightly smaller).


> I note that you used black marker.  I find black marker is more difficult
> to
> erase than the colored ones, so I no longer even leave black markers by
> the
> whiteboard.

Glad to hear we're not the only ones with this problem. :) In the end, it is
not that hard to erase, anyway not hard enough to dissuade people from using
the board on a regular basis.


> While your method should be able to get colors to work, the
> range of offset and gain to make them look right will be more narrow,
> possibly compromising the background or cutting into text in some areas.
> Everything is a tradeoff.  Use whatever works for you.

Whiteboarding in color:

http://maksimov.org/piclist/whiteboarding/whiteboarding_in_color-original.jpg

http://maksimov.org/piclist/whiteboarding/whiteboarding_in_color.jpg

http://maksimov.org/piclist/whiteboarding/whiteboarding_in_color.pdf

When printed on a color laser, this can actually fool people into thinking
it is regular handwriting. The tradeoff in this case is more vibrant colors
(higher brightness/lower contrast), or crisper lines (which is what I
usually lean toward).

Vitaliy

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