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Camera that can see computer LCD monitor 8 point font
SamQ from United States [15 posts] |
14 year
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Is there anyone out there that can verify if today's cameras (one more powerful than a webcam camera) are capable of "seeing" a computer LCD monitor well enough to detect 8 point font characters?
I'd like to use RoboRealm with such a camera to create a secretary robot that can access computers as a human would.
I've tried contacting s few camera vendors but replies are rare (suggesting nothing like that exists today).
Thanks for you input!
SamQ
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Anonymous |
14 year
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Sam,
I guess I'm not surprized by the lack of responses as it is a difficult thing to know before actually getting the camera and just trying it out. We've tried this ourselves on different screens and cameras and the results are very varied and differ in issues. It really depends on what you want out of the setup.
The first issue is horizontal resync. Ie. TV monitors refresh at a certain frequency which if the camera picks up at the wrong time you can get a strange effect. I'd recommend using the Average module to average more than one screen in order to avoid this ... or use an LCD screen which does not have that issue.
The other is lighting, typical screens are very bright and cause the camera to receive too much light ... turn up the shutter speed or decrease the brightness to reduce the blending (i.e. once pixel influencing surrounding pixels cause it is too bright).
The other is focus. Not all webcams can get very close to something without focusing correctly. A webcam with a macro lens would overcome this (normal cameras have this issue too).
In theory a webcam with 1024x768 resolution should be able to pick up a 1024x768 screen quite well ... but that never quite translates correctly. It is more like the camera needs double the res of the screen in order to get all the pixels correctly.
What initial test are you wanting to try? Can you take a screenshot, post it here and we'll try one or two cameras to see how the images come out shot from a LCD laptop screen. Hopefully this will help narrow down which cam to use!
STeven.
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SamQ from United States [15 posts] |
14 year
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STeven,
I can't begin to to adequately express my elation and gratitude towards your response!
You are the first person that ever replied with a true understanding of the basic vision problem at hand while doing so in a timely manner.
Attached is an example screen shot of a portion of this email as an example of the characters, objects and colors that must be seen clearly by a camera.
Hoping there's a camera that will do the job,
SamQ
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Anonymous from United Kingdom [99 posts] |
14 year
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Just tried it with the quickcam pro 5000 and quickcam fusion which are reasonably good quality cameras. I would say both results were pretty negative. The images from the fusion are attached. (Cropped to relative text area at the resolution.) Just some simple processing to normalize the histogram -> negative -> adaptive threshold. I have a logitech 9000 floating around in the lab which is even higher resolution that I could try.
 
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Anonymous |
14 year
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Yea, looks like a high res solution is really needed. The attached is the best I could come up with using a Logitech Quickcam for Notebooks. Looks like
http://www.amazon.com/Logitech-Portable-Webcam-QuickCam-Notebooks/dp/B000RZNI4S
Higher resolution is better and autofocus on near objects is a must. With a pan/tilt system this webcam may be capable of doing what you want.
Keep in mind that if RoboRealm can be installed on the computer then the Screen_Capture provides a much better result!
STeven.
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