I've been musing the IR bit. With next to no familiarity with the technology, what does a camera "see" when an object is illuminated with IR?
Likewise what happens if a bunch of IR LED's are in the view field of an IR camera... over exposure?
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine Sometimes I even put it in the food
look at an IR source( tv controller) with a video camera...
The OCR may not be your biggest problem. Road signs can appear practically anwhere in your field of view. Identifying objects as worthy of attempting OCR on is going to be a larger problem.
One neat trick: Most road signs (and license plates) are made with retroreflective materials. Illuminating the scene with a strobe (use IR so as not to upset bystanders) and compare that frame with one taken using ambient illumination can help in identifying them.
-- Paul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ What color is a chameleon looking in a mirror?
I can see it blink. Does that mean intense IR can overexpose?
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine Sometimes I even put it in the food
R
to a camera it is just light, so enough of it and you can get over exposure nothing magic about IR humans just can't see it
-Lasse
"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
Iust intense IR, I believe -- most CCD sensors are quite sensitive to IR, so much so that many cameras include IR filters in front of the sensor.
The Photo Speed cameras around here illuminate in IR ;-)
So I figure to surround my license plate with IR LED's ;-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine Sometimes I even put it in the food
"Jim Thompson" wrote in message news: snipped-for-privacy@4ax.com...
Send it to Mythbusters if it works... they tried a bunch of others methods without success:
Apparently if your vehicle is capable of going 170+MPH you can beat them too. :-)
----Joel
I already saw the "flip down plate" idea, which provoked my thought to have the plate "vibrate" in the x-y axes to make it blur ;-)
I noted that before as well ;-) My max speed, so far, has been ~135MPH... done on A5 in Germany.
How about slaving a strobe off of their flash?
In AZ they have to get a clear shot of the driver's face. I thought of using a bicycle reflector as a "necklace" to flash back at the camera ;-)
Probably the best way is to recognize the "Photo Enforcement" signs. They are, by law, 100 yards minimum before the camera.
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine Sometimes I even put it in the food
Hi Jim, Believe it or not, you are now in one of my fields of expertise!
Depending on the camera, first, you need to make sure to remove any IR filters in the camera. Most CMOS cameras have decently sensitivity in the near IR that can mess up the picture otherwise.
Now, if you put a pure IR pass filter in front of the camera, you get basically a black and white image in the IR. Probably not exactly what you want.
If you are imaging a light or IR source, you get an over-exposed area around the image of the source. The electrons spill over to adjacent pixels. if you have an old frame shift camera, you get long bright lines on your image.
Charlie
I don't "want"... I seek to thwart Photo Radar cameras which, to my untrained eye, appear to be using IR technology ;-)
...Jim Thompson
--
| James E.Thompson, P.E. | mens |
| Analog Innovations, Inc. | et |
| Analog/Mixed-Signal ASIC\'s and Discrete Systems | manus |
| Phoenix, Arizona 85048 Skype: Contacts Only | |
| Voice:(480)460-2350 Fax: Available upon request | Brass Rat |
| E-mail Icon at http://www.analog-innovations.com | 1962 |
I love to cook with wine Sometimes I even put it in the food
The CMOS sensors are sensitive to IR, so there usually is an IR filter in the lens assembly, making the camera mostly IR-insensitive. Usually this filter can be removed after disassembling the lens. People have actually replaced it with an IR-only (dark red) filter, to get a 'night- vision' gear.
-- Przemek Klosowski, Ph.D.
, so
=A0 =A0 ...Jim Thompson
=A0 | =A0 =A0mens =A0 =A0 |
=A0 | =A0 =A0 et =A0 =A0 =A0|
=A0|
=A0 =A0 =A0 |
I suppose it depends on the model of camera, but the red light running "cameras" I've seen are a combination of both film and CCDs. The film is what they call "extended red", going out to around 820nm. The extended red is just enough to photograph through the tinted glass. A CCD like the Sony Ex-View have response out to about a micron.
Depends on whether or not it has an IR filter. Most security-type cameras work very well in IR.
Yes, unless it has auto-iris of some sort.
--
W
. | ,. w , "Some people are alive only because
\\|/ \\|/ it is illegal to kill them." Perna condita delenda est
---^----^---------------------------------------------------------------
Ok, the idea of a ring of IR LEDs has some merit, depending on the camera. Having them shine on the plate will also often overexpose the plate, making the image difficult to determine. Depends on how good the designer was. If he has enough dynamic range built in, he can even image that, at least after image processing...
I did two major designs. On the 91 Express lanes, you would have had about a 60% chance of overexposing the plate if you used a dozen IR LEDs, but that design used standard lighting, not IR. We had good cameras and excellent processing.
On the other OC toll roads, you would have a 95% chance of overexposing. They used cheap cameras, low res images, and poor processing. But, after I was fired, I heard they upgraded everything up to to my specs, so that might no longer be true!
Charlie
Charlie E. wrote:
That last bit has been foremost in my mind throughout this thread.
**Haven't those guys thought of this stuff already?**I was wondering if putting something especially shiny in the IR (like a Pyrex plate) in front of the numbers would affect things.
...and is a "protective layer" over your licence plate allowed?
Don't know about other states, but it is prohibited to cover your license plate with any material in California, especially if it is not
100% transparent.They used to make a cover that due to embossed lensing, made it possible to only view the plate from directly behind, probably with a field of view of only 15-20 degrees. That soon became an automatic traffic stop, when the cop would then 'inspect' your vehicle for other infractions!
Charlie
...meybbeee i dunnoh whan MY plate to git doity?
...and the definition of "100% transparent"?? Does that mean one must wash dirt off of the plate every day?? Maybe my dirt absorbs IR?
On my 4x4 that's also known as 'mud'.
-- Paul Hovnanian mailto:Paul@Hovnanian.com ------------------------------------------------------------------ If God is perfect then why did He create discontinuous functions?
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