Contex XD2490 Service Manual page 44

Screen Resolutions are normally 72 pixels per inch of screen.
Additional detail is thrown away by the screen display driver,
anyway. For Printer Resolution scans, you need 150 dots per
inch and above for good results on the printed output. One
must find the level of detail that is still visible in printed output
on the printer in question, and not dramatically increase the
size of a saved file without bettering the result.
RGB
Red, Green, Blue. These additive primary colors are the basic
elements of white light. By mixing them on a computer moni-
tor or in a scanned image file, other colors can be created. For
instance, Red and Green produces Yellow, and equal amounts
of all three produce gray.
RIP
Raster Image Processor. A RIP is a special software that
converts scanned images into a color dithered (halftone) image
that can be output directly. An image must be 'ripped' before it
can be output on a CMYK device, e.g., an inkjet printer.
Rotate
To turn the picture left (clockwise) or right (counterclockwise)
from the orientation in which it was scanned.
Runlength Encoding
A method of compressing raster or bitmap data by represent-
ing "runs" of white or black dots along a scanned line as the
number of dots in each run. Many variations of this scheme
exist, with varying compression efficiency. Typically, run-
length compression formats yield a file 20-25% the size of an
uncompressed file.
Saturation
The level of colorfulness of the picture. A picture with high
saturation has vivid color. A black and white picture has zero
saturation. The purity of a color or the degree to which it is
diluted with white light. Red is a highly saturated color. Pink
is a diluted red (has lower saturation).
Saturation is one attribute of color in the color space called
HSV (Hue Saturation, Value). Saturation is a characteristic
indicating the vibrancy or intensity of a hue. A color with high
saturation will appear more intense than the same color with
less.
Scale
To reduce or enlarge the size of a picture proportionally.
Scanner Calibration
A program that helps adjust the scanner to achieve stable
C-6
Appendix - C --- Scanner Terms
colors and work with a printer. Calibration gives better scan-
ning results. The program should be run whenever changing
printing equipment, toner, and inks, and whenever getting poor
results when printing pictures.
Screen Calibration
A program that helps adjust the computer screen to get the best
display of scanned pictures and documents. This program is
run during installation and should be used again any time that
the computer screen or the lighting around the computer is
changed.
SCSI (Small Computer System Interface)
An interface that allows hard disks and other high-perfor-
mance peripherals to be attached to Macintosh and PC com-
puter systems.
SCSI Card
The printed circuit card that came with the scanner. With its
driver software, the card allows the computer to talk to the
scanner. The card is ASPI compatible with a SCSI-II output
connector.
SCSI
Small Computer System Interface. Specification of interface to
computer equipment like disks, printers, scanners etc.
Shadow Detail
The amount of detail contained in the dark parts of an image.
It is desirable to maintain shadow detail, but there is a risk
of decreasing overall contrast if one lightens the shadow too
much in an attempt to expose additional detail. If an image is
scanned without shadow detail, it will be impossible to regain
detail using an image editing program.
Shadow
The darkest part of a picture; reproduced as black onscreen or
when printed.
Sharpness
An attribute of a scanned image and also an attribute of scan-
ner quality.
SRGB
Hewlett-Packard and Microsoft proposed the addition of sup-
port for a standard color space, sRGB, within the Microsoft
operating systems, HP products, the Internet, and all other in-
terested vendors. The aim of this color space is to complement
the current color management strategies by enabling a third
method of handling color in the operating systems, device
drivers and the Internet that utilizes a simple and robust device