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BS1 Slow Scan Low-Res Camera — Parallax Forums

BS1 Slow Scan Low-Res Camera

ercoerco Posts: 20,257
edited 2010-09-25 01:25 in BASIC Stamp
Anybody tried it? Tracy, Phil, Mike?

2 servos do a slow point-to-point XY scan of a well-lit scene, aiming a very directional phototransistor & lens system that RCtimes the brightness of each spot. Output could be in many forms, including a course DEBUG screen that recreates the scene onscreen with different characters. Yes, I'm talking low-res, maybe 40 or 60 characters (pixels) wide.

Somebody must have done this using a Stamp. I've heard of a similar setup from the 1980s and the Commodore 64 crowd. Take an analog 2-pot joystick with a similar phototransistor setup, and manually hand-scan a scene, reading X,Y and brightness pixel by pixel, recreating on-screen.

Sure a BS2 or Prop could do it much better & faster. But I'm a simple guy; I like max bang for the buck. I'll proceed if no one has done it yet.

Comments

  • Spiral_72Spiral_72 Posts: 791
    edited 2010-09-24 11:33
    I recall reading about someone doing this with a linescan module, but I don't remember if it was the BS1 or BS2.

    Also, someone else used an optical mouse sensor. I think it was a 16x1 or 16x16 pixel gray sensor. I believe this was done with a computer, but I don't see why it wouldn't apply. You'd need a lens to increase the FOV.
  • kf4ixmkf4ixm Posts: 529
    edited 2010-09-24 11:36
    I know Phil done something like this not too long ago using the linescan imager and bs2pe Mobo mounted to a servo, he scanned an image of a dollar bill. i think he also modified it to produce a color image too using rgb filters on the lens and making 3 scans to produce the color image. i cannot find the post now, but i know it was in the old forums somewhere.

    Found it!
    http://forums.parallax.com/showthread.php?t=121080&highlight=linescan\
  • Mike GreenMike Green Posts: 23,101
    edited 2010-09-24 11:42
    The BS1 has very very limited storage, like maybe 6 words of variable space and 256 bytes of program space. The BS2 has about twice as much variable space, but that's still not enough for an image. The BS2p/pe/px Stamps have scratchpad RAM ... huge, all of about 128 bytes ... with two pixels per byte, you could get 16 x 16 pixels. You could attach some Ramtron FRAM or SPI SRAM for an external buffer more than big enough to hold decent images (32K or more) and the BS2p series Stamps have enough program space to handle a task like this.
  • ercoerco Posts: 20,257
    edited 2010-09-24 13:51
    Thanks for the quick responses! I realize the BS1 has very limited memory; my goal is not storage, but to export the scan to some type of display. I thought generating a pixely image grid on a debug screen would be novel. Clearly there are far better hardware and software means to accomplish the task, I just particularly enjoy re-inventing the wheel when I get a crazy thought. I know that linescan module is nice, but that's cheatin' as far as I'm concerned! :)
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-09-24 17:29
    erco wrote: »
    I know that linescan module is nice, but that's cheatin' as far as I'm concerned! :)
    You'd only be cheatin' in one dimension, though! :)

    Instead of a pan/tilt for your light sensor, you could also try a Nipkow Disk. It would only require one servo, instead of two. It's what I used with my thermal imager.

    -Phil
  • ercoerco Posts: 20,257
    edited 2010-09-25 01:25
    THAT is the spirit, PhiPi! You always have interesting ideas and workarounds!
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