Fred Weinhaus on wrote...
| >Here is an example. You will have to randomize the rotation and
| >translation as well as the characters.
| >
| >convert -size 290x70 xc:white -bordercolor black -border 5 \
| > -fill black -stroke black -strokewidth 1 -font TimesNewRoman
| >-pointsize 48 \
| > -draw "rotate 30 translate 40,30 text 0,0 'A'" \
| > -draw "rotate -10 translate 65,50 text 0,0 'n'" \
| > -draw "rotate 5 translate 110,40 text 0,0 '3'" \
| > -draw "rotate -20 translate 130,100 text 0,0 'c'" \
| > -draw "rotate -5 translate 190,70 text 0,0 'x'" \
| > -draw "rotate 10 translate 240,10 text 0,0 'H'" \
| > -fill none \
| > -strokewidth 2 -draw "bezier 20,70 45,10 100,70 140,10 " \
| > -strokewidth 3 -draw "polyline 150,20 200,60 280,30 " \
| > captcha.gif
| >
| >see http://www.fmwconcepts.com/misc_tests/captcha.gif
| >
| >
| After some further testing, the draw text is better done as follows:
|
| -draw "translate 50,10 rotate 30 gravity center text 0,0 'W'" \
|
| where I have inserted gravity center making the translate relative to
| that point.
|
| Using my method below it was hard figuring out what translate to
| apply as it was inconsistent.
|
Actutally -annotate is better still as it has text positioning
and rotations all built in.
There is however no one 'catchpa' method. and just about every site has
its own techniques for generating test that humans can read but optical
character readers can't decipher.
Use very different and unusual fonts, can also be a great way to make
good catchpa's.
Please note however one Spamer has websites which display very recently
aquired catchpa's to humans, and have then decode it. The software then
uses that to jump into the site they are attacking to do the desired
'naughty behaviour'. In essence, even captcha's can be defeated by a
well designed automatic system using human guinea-pigs.
Anthony Thyssen ( System Programmer ) <[EMAIL PROTECTED]>
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"e, s, s, s, n, e, e, nw, get chest, se, n, d" - Sound familiar??????
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Anthony's Home is his Castle http://www.cit.gu.edu.au/~anthony/
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