Tinted glass

That's what i've been waiting for!
I have lenses and the knowledge waiting for this project: Digital large
format camera...

The fact that the CIS images obtained with these cheap CANON scanners
are of low resolution is a none-issue for this proyect. What really
bothers me if these scanners still work if the light source is taken away..

The fact that it is a B/W sensor is quite cool! This produces a very
versatile B/W - COLOR scanner via multiple scans using any filter you
like. This is perfect for IR- and alternative processes!

I'll be hunting for a 600 DPI version of these Scanners. This should
produce 30 MPIX images!
Anyone can help me with model names and numbers?

Tadeuz

Raphael Bustin wrote:

On Sun, 01 Feb 2004 03:52:37 -0300, Tadeuz Jalocha
wrote:


Hello Marv,

It is'nt as easy it initially sounds, you need to remove the lens and
the mirrors of the scanner an need to focus directly on the surface of
the CCD. That's because if you leave the lens of the scanner in the
optical path, you'll get only an visible image when the tree elements
(CCD - lens of scanner - LF-Lens ) are in one line. Think of a very
strong hot spot.
This produces a new problem. Because the CCD's are shorter than the
papers (flatbed) width they scan, you'll get a strong anamorphic effect
if you achive to proyect correctly the image in the CCD of the stripped
down scanner. That's because the scanner sees an image that is strongly
compressed in vertical-to-travelling direction but not compressed at all
at travelling direction. The scanner logic needs to adjust the data to
give you an image with correct proportions.

Does anyone know, if the sensors of the cheapest Canon scanners (LIDE
techonlogy) are as long as the papers are wide? If so, this would be a
perfect candidate! I have been talking with Agfa, forget about their
scanners for such a proyect, the CCD are way too short.



The Canons use CIS (contact image sensor) technology,
where the sensor is indeed as wide as the scan bed -- but
relatively low resolution. There is no "optical" system to
speak of - no lens, no mirrors. Illumination of the target is
by red/green/blue LEDs that also run the width of the
target. Amazingly this is cheaper to build than the typical
CCD scan bar. The sensor itself is monochrome; color is
obtained by illuminating the target successively with the
red/green/blue LEDs (as in the Nikon film scanners also.)

The other type of scan head uses a CCD sensor that
typically has only 30-40 mm optical width. In this kind of
scan head there is an array of folded mirrors and a lens
right in front of the CCD sensor. The CCD system yields
much higher resolution, even though the sensor is much
smaller. Illumination in this case is via cold cathode
(fluorescent) embedded in the scan head. The sensor
is "color" ie, there are three photosites per pixel, one
each for red, green, and blue.

CIS sensors are cheap, and allow for a very shallow
scanner design. They are typically used in card readers,
and fax machines. The majority of flatbed scanners use
CCD scan heads.


rafe b.
http://www.terrapinphoto.com

Tadeuz:

You might check on Google for some of the other posted information. My
search has turned up the slightly interesting idea that the CISs run
"wide open" are essentially 600dpi devices and that upscaling the scan
rate or down scaling it is really a multiple or fraction of that number.
I will try throwing the CCD out the window tomorrow to see if I can make
some sense of what the scanner is showing me.

In addition, since most of these devices use TWAIN, get yourself a copy
of the TWAIN Toolkit (free) at Twain.org. It allows you to drive the CCD
without using a graphics program.

Regards,

Marv

Tadeuz Jalocha wrote:
That's what i've been waiting for!
I have lenses and the knowledge waiting for this project: Digital large
format camera...

The fact that the CIS images obtained with these cheap CANON scanners
are of low resolution is a none-issue for this proyect. What really
bothers me if these scanners still work if the light source is taken away..

The fact that it is a B/W sensor is quite cool! This produces a very
versatile B/W - COLOR scanner via multiple scans using any filter you
like. This is perfect for IR- and alternative processes!

I'll be hunting for a 600 DPI version of these Scanners. This should
produce 30 MPIX images!
Anyone can help me with model names and numbers?

Tadeuz

Raphael Bustin wrote:

On Sun, 01 Feb 2004 03:52:37 -0300, Tadeuz Jalocha
wrote:


Hello Marv,

It is'nt as easy it initially sounds, you need to remove the lens and
the mirrors of the scanner an need to focus directly on the surface
of the CCD. That's because if you leave the lens of the scanner in
the optical path, you'll get only an visible image when the tree
elements (CCD - lens of scanner - LF-Lens ) are in one line. Think of
a very strong hot spot.
This produces a new problem. Because the CCD's are shorter than the
papers (flatbed) width they scan, you'll get a strong anamorphic
effect if you achive to proyect correctly the image in the CCD of the
stripped down scanner. That's because the scanner sees an image that
is strongly compressed in vertical-to-travelling direction but not
compressed at all at travelling direction. The scanner logic needs to
adjust the data to give you an image with correct proportions.

Does anyone know, if the sensors of the cheapest Canon scanners (LIDE
techonlogy) are as long as the papers are wide? If so, this would be
a perfect candidate! I have been talking with Agfa, forget about
their scanners for such a proyect, the CCD are way too short.




The Canons use CIS (contact image sensor) technology, where the sensor
is indeed as wide as the scan bed -- but relatively low resolution.
There is no "optical" system to speak of - no lens, no mirrors.
Illumination of the target is by red/green/blue LEDs that also run the
width of the target. Amazingly this is cheaper to build than the
typical CCD scan bar. The sensor itself is monochrome; color is
obtained by illuminating the target successively with the
red/green/blue LEDs (as in the Nikon film scanners also.)

The other type of scan head uses a CCD sensor that typically has only
30-40 mm optical width. In this kind of scan head there is an array
of folded mirrors and a lens right in front of the CCD sensor. The
CCD system yields much higher resolution, even though the sensor is
much smaller. Illumination in this case is via cold cathode
(fluorescent) embedded in the scan head. The sensor is "color" ie,
there are three photosites per pixel, one each for red, green, and blue.

CIS sensors are cheap, and allow for a very shallow scanner design.
They are typically used in card readers, and fax machines. The
majority of flatbed scanners use CCD scan heads.


rafe b.
http://www.terrapinphoto.com