Image Quality—Epson ColorTrue® Imaging System (cont.)
3. Processing: Many Epson scanners use a custom ASIC (Application Specific Integrated Circuit) for fast
scanning. Key features include:
Line correction captures and processes full RGB color for every pixel and minimizes color fringing in
subscan direction.
Zoom capability enables smoothest edges along diagonal or curved lines and achieves higher
interpolated resolution
On-board memory allows for Auto Area Segmentation (AAS) and Text Enhancement Technology (TET)
processing within the scanner—AAS and TET are independent from PC or Macintosh processing,
allowing the scanner to work with better "raw" data.
Additionally, Epson scanners have a pixel optimization feature
that uses the full resolution of the scanner's CCD, even scanning
at a lesser resolution. The benefit of this feature is truer image
quality.
For example, on one of the Epson 600 dpi Perfection
scanners, when scanning an image at 300 dpi, the scanner
still uses all 600 pixels per inch to scan the image, then
averages the data to yield the lower resolution image.
Some competitive models lower resolution by turning off
some pixels to capture less image data.
Image Quality—Color CCD
All Epson scanners use a color CCD which uses a single white light source, instead of a monochrome CCD
and three light sources. The color CCD results in faster scanning speeds and the ability to scan three-
dimensional objects without producing color "ghosts."
Key Differences Color CCD
How it works
Result when
scanning three-
dimensional objects
Scanner Technical Brief—Page 5
Red, green, and blue are quickly captured
in the color CCD illuminated by a single
light source.
Glass
Color CCD
Single light source allows precise
alignment when scanning non-flat
surfaces
Monochrome CCD
three separate lamps are fired for eachline
of a scan, slowing the scanning speed.
Glass
Monochrome
CCD
White light
source
The three lamps can cause misalignment
when reflected from non-flat surfaces.
Epson Method:
Competitive Method:
On
Off
On
Off
On
Red light
source
Green light
source
Blue light
source
Off
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