Tony Nixon wrote:
<snipped>
> I have done some basic playing around with a video camera to see what
> signal can be obtained with a yellow line contrasted against a bitumen
> background. The idea is to use the shift in the yellow signal to decide
> how far the vehicle is off center and use the steering servo to correct
> any errors. There are no bends in the line.
>
> I was hoping a filter of some sort would help with the contrast by
> darkening all other colours.

If you want to "intensify" one particular color, then use a filter of that
color.  Find a filter of as similar a yellow as possible, and put that on
the camera.  What the filter does is pass light of the same color as the
filter, and attenuate all other colors.

Something else to consider is use a black and white camera for this.
Putting a yellow filter over the lens of a B&W camera and pointing it at a
yellow line will *really* make the line stand out.  I'm not exactly sure
what bitumen is, but if it's what's generally referred to as asphalt here in
the States then it's generally a pretty dark black.  And with a B&W camera
with a yellow filter, that yellow line outta be damn near impossible to
miss.  Post-filter, it'll be almost dead white against a dead black
background.

Of course, this is all presuming that I'm remembering my intro photography
course correctly.
--
Mike Werner  KA8YSD   | He that is slow to believe anything and
                      | everything is of great understanding,
'91 GS500E            | for belief in one false principle is the
Morgantown WV         | beginning of all unwisdom.

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