subliminal color images

[Dave Long]

> 	=E11=E1	green	vert	"\\"
> 				"\\"

Heh.  When we visited France (in a region whose old duke had a one-word=20=

blazon) we were kvetching about how "verre", "vert", and "ver" are all=20=

homophones, and our host said he thought there were actually about 6 in=20=

that family, including "vair" (as in the heraldic vairy).  So it's=20
possible to argue that Cinderella's dancing shoes were originally=20
fur-trimmed, instead of being a silica product, and the story mutated=20
along the way.

>> why not support the classic engraving marks? that way cellphone + old
>> book/reproduction =3D color engraving.

Who needs screensavers when one can just rotate the phone to watch the=20=

pretty colors change? :-)  Somewhere I have a technical drawing book=20
which had a list of "conventional" crosshatching patterns for different=20=

materials.  But either that wasn't really common practice, or it's in=20
that black hole of too recent to be of historical interest, and too old=20=

to naturally occur on the web.

>>> I didn't mean it would work by accident --- I meant that software in
>>> the cellphone could decode a chroma signal from a barcode "hidden" =
in
>>> the image, for example in the angle and spacing of patterns of
>>> parallel lines used to approximate a grayscale as in an engraving.

OK, now I understand -- and I suppose correcting for perspective and=20
lighting would be fairly trivial in comparison with processing=20
satellite datasets.
(you all must have better phone cameras than I do.  I just tried=20
capturing a PDF417 barcode, printed at about 0,6mm per pixel, and the=20
resulting VGA photo is pretty poor, unless the 4-of-17 is sparse enough=20=

that it's unambiguous even when the the symbols are smeared into=20
blacks, greys, and whites)

>>> Venezuelan paper money has areas that appear from a distance to be=20=

>>> one
>>> solid color, but consist of many areas of fine parallel lines at
>>> different angles.

If you ever looked at a $20 and wondered "what the heck did this=20
Jackson guy do, anyway", it's hard to beat Swiss bills for convenience.=20=

  At least up through the 200 they're all artists or writers or=20
otherwise creative types, and there is a small (8x8) block on each bill=20=

which contains a short biography in very, very, fine print.

>>> But the same scheme could be applied to encode more interesting
>>> information subliminally into the print; perhaps the frequency of =
the
>>> lines could represent saturation, and their angle could represent=20
>>> hue.

The heraldic conventions are not far off -- make hue a (somewhat messy)=20=

function of angle, and determine saturation by dash length (continuous=20=

lines =3D=3D fully saturated) and you'd come pretty close -- but Or =
would=20
be at 5/8=B9, and Bleu celeste at 7/8=B9.  Maybe stippling would imply=20=

changing the white balance instead, and that would recover a nearly=20
historical Or?

-Dave