filmscanners: pseudo1200dpi scanners (was RE: Pigmented inks was Re: filmscanners: SS4000 and LS-2000 real value?)

[Clark Guy <guy.clark@sbt.siemens.com>]

Hi, Pete!

Isn't the Epson 1200dpi scanner one of those that uses two 600dpi CCD
arrays, offset by 1/2 pixel?  If so, then of course it looks like a 600 dpi
scanner-- it is merely doing hardware interpolation.  

The only way this kind of dual array sensor could work would be if the
individual pixel elements on the CCD were half the size of their regular
600dpi arrays, so that the area seen by the offset element wasn't just the
combination of that area seen by the adjacent CCD elements of the primary
array.

My two cents,anyway!

Guy Clark

-----Original Message-----
From: Photoscientia [mailto:photoscientia@photoscientia.co.uk]
Sent: Monday, January 29, 2001 3:45 PM
To: filmscanners@halftone.co.uk
Subject: Re: Pigmented inks was Re: filmscanners: SS4000 and LS-2000
real value?

>>>>>>snip!<<<<<<<

I recently bought one of their so-called 1200dpi flatbed scanners, which had
worse image sharpness than the cheap 600dpi Mustek that I had intended to
replace. The 1200dpi was simply 'empty resolution' containing no detail,
because they had obviously skimped on the optical system, and the image had
the
same appearance as 600dpi interpolated to 1200.

Another half-arsed Epson design job, which in my view was again falsely
advertised.

The box clearly stated 'true 1200 dpi optical resolution', and this was
plainly
nonsense, since the lens couldn't actually resolve anything near that. I
tested
it with a resolution test plate, and it struggled to about 600dpi. Contrary
to
popular belief, this isn't due to the glass in the way. Removing the glass
platen gave the same result. It just has a poor lens.

I see Canon will be pouring millions into R&D on their printer range over
the
next few years.
Good luck to them!

Regards,     Pete.