[Elphel-support] linescan mode

[Andrey Filippov]

On Thu, Feb 4, 2010 at 7:35 AM, Michael Aschauer <m at ash.to> wrote:

> Andrey,
>
> I currently failed to downgrade.
> Does that mean this mode should work in 7.1.x firmware? or things are less
> likely to break?
>
>
> best,
> m,-
>
> Michael,

I will need to test the code some more (current version is really
experimental and have some glitches), but it seems that the lines can mode
is back in 8.0.6.6 firmware. It supports up to 16K of lines in each
composite frame (frames are supposed to perfectly match - no gaps between
them). With full line of 2592 pixels the regular 5MPix sensor of the 353
camera can handle about 2500 line pairs (they go in pairs as the sensor is
color) per second.

The same mode should be useful to get the top fps for small images avoiding
the CPU overhead related to the file headers and just processing the frame
interrupts. It is possible now to combine multiple small images (not just
2-line rectangles) to the total height of up to 16K lines in a single
composite image.

Here are some samples (original and some - rotated/cropped):

http://community.elphel.com/pictures/linescan/

It is fun that cars going in the opposite directions on the freeway are
going the same direction on the image. You may also notice something like
huge chromatic aberration - it is caused by the car crossing one of the line
in a color pair before the other.

Many images are acquired at reduced rate (they have "582lps" in the name) so
the cars look more proportional, at the full 2425 lp/s they look too long.

Andrey
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