[sane-devel] genesys backend

[Pierre Willenbrock]

Hi

Stéphane VOLTZ schrieb:
> Le Lundi 29 Août 2005 20:01, Pierre Willenbrock a écrit :
> 
...
>>Next i'd like to rewrite genesys_read_ordered_data to be more
>>maintainable and able to convert the cis style planar data to "chunky"
>>data.
>>      
> 
>         It is indeed a rather complicated function. Data doesn't come in an 
> easy form. But I don't exactly see why you want to convert to planar data
> first.
> 

What i meant was that the function needs to be able to convert from
planar data to chunky data. CIS color scans work mostly like grey scans,
but the led color is changed every line, and scancnt is incremented
every third line. This leads to whole lines of a single component in the
output data of cis scanners:

cis:
RRRR...
GGGG...
BBBB...

ccd:
RGBRGB...


> 
>>For that i need to know what the "stagger" effect exactly is. I am not
>>sure i got that one right.
>>
> 
> 
>         At high motor resolution, lines are staggered, ie they aren't
> horizontal lines. On pixel is on a line, the folowing colunm is on another ...
>         A drawing may be more evident:
> 
>         'O' are pixel of on horizontal line, '.' other lines data
> 
>         ...O.....O.....O.....O.....O.....O.....O
>         ..O.O...O.O...O.O...O.O...O.O...O.O...O.
>         .O...O.O...O.O...O.O...O.O...O.O...O.O..
>         O.....O.....O.....O.....O.....O.....O...
> 
Is that a property of the ccd-array? The high motor resolution can't
possibly be the reason for that pattern. The most error i would expect
from motor activity is a difference of a single line between the first
and the last pixel in the scanned data.
Is that pattern correct? I would expect something more like this:

...0...0
..0...0.
.0...0..
0...0...

But i would guess it heavily depends on the physical layout of the
optical cells on the ccd chip.

In the end this is a multiline operation like line distance correction,
so i will do line distance correction directly after un-staggering.
> 
...
> Regards,
>         Stef
>  

Regards,
  Pierre