Tabletop Assisted Vision Camera Suggestions...

[JMThomas 0]

I'm sure this isn't new, but I've zero experience in choosing camera equipment. I can program PCs and build hardware interfaces, but again almost no nuts and bolts experience with CCTV. I expect that what I learned a couple of decades ago in my Electrical Engineer classes is moot.

 

I want to hang (mount) a camera 15+ inches above a 15" square target. Items up to 4 inches in height are set on the target for examination.

 

The camera/lens is externally controlled for zoom, say 2x to 16x. Everything else (white balance, gain, focus, etc.) is done auto-magically in the camera.

 

The goal is image magnification, not image processing. Think of a telephone book or newspaper on the target, and a vision impaired user watching the monitor.

 

The camera output destination doesn't matter to me. I don't care if I display the image on a PC monitor or on a TV (NTSC). Finding a KISS (almost) plug it all together solution would be outstanding luck! Adding a computer with PCI card and software doesn't bother me; I'm good at integrating parts to work together.

 

I have seen cameras with control connections (and control buttons) on the back side. Here are two examples:

Am I getting warm, or should I be looking for something very different?

 

I can build an external box near the camera with buttons for the user.

 

I can connect a serial control interface (Pelco-d?) to a computer and program a driver.

 

And of course, I'd like to do it cheap, say under $200 for the camera. I can solder PC boards and write software and do metal work in my garage.

 

Questions...

 

1. How am I for the physical dimensions? Would shrinking the target help? Am I asking for too much depth of field, or zoom? Will a 60 watt bulb provide good enough illumination? Just what are reasonable expectations for cheap reliable equipment?

 

2. How much resolution is needed to comfortably read small (8 point type? phone book white pages?) text at 1.5x or 2x magnification?

 

Say I start with an image at 8x with a NTSC signal on a 19" monitor, and then iteratively reduce the magnification. How close to 1x should I expect to get before the picture quality is no longer comfortably readable for a normal sighted person? How about a signal degraded by adding a RF modulator?

 

Would choosing a different signal (S-video, Y-Pb-Pr) be a reasonable option?

 

3. Are there cameras that drive computer monitors, e.g. VGA, 800x600, 1024x768?

 

4. Should I be looking for an integrated lens/camera, or to buy a basic camera and add a motorized lens (that will need some software to control it)?

 

5. Do I need to go the commercial CCTV route, or might high end "web cams" have sufficient resolution, auto focus and zoom range?

 

Thanks for your time. Just point me at some good info, and I can learn!

[Owain 0]

you need to start with how you are going to magnify the image. Either analogue video with optical zoom, which will need a zoom lens and a controller, or a megapixel camera and do the zoom digitally.

 

Zoom lenses, controller keyboards etc can get expensive and I'd be inclined to use digital. I'd suggest starting with a megapixel webcam as these are quite cheap, and seeing how you get on, or asking the people at networkwebcams as they're expeirenced with megapixel IP cameras.

 

If the aim is magnification of print i.e. a 2-dimensional surface, then video magnifiers are already available, output to either TV, VGA or USB. I don't know how well they'd cope with 3D objects, and as with most things for 'the disabled' the prices are hiked.

 

http://www.eschenbach.com/products-video-magnifiers-desktop.htm

[pete1606 0]

I have poor vision so I know what it is like. I was a teacher and as a result I began working in classrooms with document cameras. Think of document cameras as a 21-centruy overhead project, but this one is digital and the items you view do not need to be transparent like the old overhead projectors required.

 

I bought a document camera for myself while I was in grad school to help ease eye strain from textbooks with small print. I bought an Elmo brand CO10.

 

It is small lightweight, comes with a carrying bag, you can connect it to a TV via composite video connections or connect it to a computer via VGA monitor connection and it has a pass-thru monitor port so you only need one VGA port on your computer, but the way I PREFER to connect it is via USB!

 

I am going to post some screenshots in a few minutes.

[pete1606 0]

The fist image was taken via the software that came with the document camera. I placed the adjustable arm that the camera is on about three inches from the magazine. I did NOT use the digital zoom. I placed a ruler in the photo to give you an idea how small the text is. The photo is of an add in the back of Popular Photography magazine.

 

 

the second photo is taken with the arm about 12 inches off the surface. I used the digital zoom, for this pic. As you can see putting the arm lower produces a better quality image, than the digital zoom.

[pete1606 0]

The fist image was taken via the software that came with the document camera. I placed the adjustable arm that the camera is on about three inches from the magazine. I did NOT use the digital zoom. I placed a ruler in the photo to give you an idea how small the text is. The photo is of an add in the back of Popular Photography magazine.

[attachment=1]pm-magizine ad-no zoom.jpg[/attachment]

 

the second photo is taken with the arm about 12 inches off the surface. I used the digital zoom, for this pic. As you can see putting the arm lower produces a better quality image, than the digital zoom.

[attachment=0]pm-add-digital zoom.jpg[/attachment]

 

I forgot to mention in the second image that used the digital zoom I didn't zoom all the way in, as you can see when I took the screenshot, there is already a loss of some detail in the text.

 

If you have any more questions please feel free to ask.