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 Topic
areas
The
Active Print project
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Q: What is the Active Print project?
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A: The Active Print
project is a collaboration between companies investigating
how to bring about a new ecosystem. That ecosystem is the
"printed internet", in which everyday printed and displayed
items become links to content, retrieved with camera phones.
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Q: Is Active Print a new idea? |
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A: The idea of reading codes with a camera
and using the data in them to retrieve relevant content
has been around for a long time. The companies participating
in Active Print represent significant experience with that
technology. However, an important shift in the past two
years or so is that camera phones have become capable of
reading codes. Since camera phones are becoming prevalent,
there is a new opportunity to make this a mass phenomenon.
It is already big
in Japan. What is novel about the Active Print project
(apart from some of the specifics of the technologies we
are developing) is that we represent an ecosystem-wide look
at how to link printed matter to online content, including
understanding the user and authoring experiences, and developing
business models. |
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Q: When and how did the Active Print project begin?
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A: Active Print began life as the "Active
Posters" research project at HP Labs in Bristol, in Autumn
2004. External partners joined and external projects took
place from Spring 2005. The initial focus was on posters
because they have the interesting property that they are
situated, often in places where people dwell; for example,
there are posters at bus stops and inside transportation.
Since then, the project has expanded its remit to all forms
of printed matter, as well as displays. |
Glass
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Q: What is popup text for? |
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A: The popup text provides an immediate
way of engaging the user "beyond the paper", without any
need for network communication. Indeed, some codes contain
only popup text, needing no links to network content. The
popup text can be used, for example, to tell the user more
about what is printed, or to tease the user into activating
the code. |
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Q: What types of connection can Glass make from
codes? |
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A: Activating a code can cause a download,
or send a text (SMS) message, or make a call, or.... The
idea is for codes to be extensible to various types of interaction.
An important research goal of Active Print is to understand
in which types of situation these different interaction
models are appropriate, and to support them accordingly.
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Q: What is the purpose of the History, and how big
can it grow? |
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A: The History is for "after the fact"
code review and activation. Activated codes are automatically
saved, but users can also save coded links if they are too
busy to activate them in the moment. Users can use the saved
codes to revisit content themselves, and to show their friends
what they experienced. They can also "give" the code to
their friends, by displaying it on their camera phone for
reading. The History can hold up to 100 codes. If that limit
is reached, the oldest items are deleted as new ones are
added. But the user can delete individual items of their
choosing or clear the entire history list. |
Codes
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Q: What types of codes are supported?
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A: At the moment, we support only QR codes
and Datamatrix codes (for examples, look here).
Many other types of code exist, and we may go on to support
others. In particular, as phone capabilities improve, the
standard linear barcodes on products in the supermarket
will be supported. QR and Datamatrix codes are our initial
choice because they represent a good balance between important
factors such as readability, robustness to errors, data
density and aesthetics. They are also widely used standards.
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Q: How much data can QR and Datamatrix codes hold?
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A: The answer depends on the target phone's
optics and the resolution of its imaging device. The more
data a code holds, the closer the phone needs to be held.
That is because the code needs to occupy as many pixels
as possible, so that the code's cell size is sufficiently
larger than the pixel size. A code with too much data for
the phone's capabilities tends either to get out of focus,
or to be too big for the screen. That is because ordinary
camera phones (without a macro lens) are designed for taking
pictures of subjects such as people, from a distance of
about a metre or more. We expect camera phones to evolve
so as to be better suited to the Active Print paradigm.
A
rule of thumb is that codes of 2-5cm on a side can contain
up to about 100 bytes and still be readable at video rate
using a camera phone with VGA resolution. It's a good
idea to mininimise the length of URLs in codes using a
service such as tinyurl.com.
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Q: How large should a code be printed?.
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A: This depends on such factors as the
capabilities of the target phones, the amount of data in
the code, the symbology used (QR or Datamatrix - the latter
is denser), and the distance from which the user is expected
to read the code. A
rule of thumb is that codes smaller than about 2-3cm on
a side are too difficult to read with most camera phones
currently available.
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Q: Should I use Datamatrix or QR codes?.
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A: It's up to you. Datamatrix codes are
somewhat denser and faster to read but have different aesthetics.
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