subliminal color images
dave.long at bluewin.ch
Tue Oct 17 14:53:52 EDT 2006
> =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" =
>>> 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
(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=
>>> 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 =
>>> lines could represent saturation, and their angle could represent=20
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 =
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
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