Transcript scanningbasics - Multimediaarts.net

Scanning Basics
Where images come from....
• An image can be created, opened,
edited, and
saved in over a dozen different file formats in
Photoshop.
• Of these, you might use only a few, such as
TIFF,and EPS for print GIF,]PEG,for the web, and
the native Photoshop file format for your master
documents.
•Because Photoshop accepts so many formats,
an image can be gathered from any number of
sources including: scanners, drawing
applications, PhotoCDs, still images, video
captures, or even other operating systems. You
can also create an image entirely within
photoshop.
The Scanner...
• Using a scanning device and scanning
software, a slide, flat artwork, or a
photograph can be digitized
• (translated into numbers)from analog to
digital
• so it can be read, displayed, edited, and
printed by a computer.
• You can scan directly into Photoshop
(Save as psd) or you can use other
scanning software and save the scan in a
file format that Photoshop opens. Use Tiff
or BMP
Quality and Settings
Always start with as high quality an original as possible...
Scan at 100% of original image size
Scan at highest quality for target out put
Two types of scanners...
Flat bed scanners
High quality scanners...
Flat bed scanners
•inexpensive
•produce an RGB scan.
•Good for low to average quality print work
•Excellent for web or onscreen work
High end
scanners such
as...
high-resolution CCD scanners, such as a
Scitex Smart-Scanner, or on a drum
scanner or a slide scanner for
transparencies
CMYK scans, which are usually
large in file size.
High end
scanners such
as...
professional-quality output mid to
high end print work
Can optically distinguish subtle
differences in luminosity, even in shadow
areas
High end
scanners such
as...
capture a wide dynamic range of color
more accurate color and crisper details
Parameters of a scan...
Resolution
is the number of pixels an image contains,
and it is measured in pixels per inch. The
monitor's resolution is also measured in
pixels per inch (72 pixels per inch). Output
devices also have their own resolution,
which is measured in dots per inch The
higher the resolution of an image, the
more pixels it contains, and thus the more
information for detail, but the larger will be
its file size.
Parameters of a scan...
Resolution is also...
DPI Dots per inch or PPI Pixels per inch:
The number of dots in the image, the
higher the number of dots, the higher the
quality of the image
Parameters of a scan...
Color mode and use
RGB for onscreen display
CMYK for print
Parameters of a scan...
bit depth=the number of colors in the image
32 bit 16.7 million colors + alpha channel
24 bit 16.7million colors
16 bit Thousands of colors
8 bit 256 colors
also known as an index palette
Parameters of a scan...
Image size or Dimensions The width
and height of an image
The physical dimensions
Pixels=web
Inches=print
Parameters of a scan...
File size
The file size of an image, which is measured
in bytes, kilobytes, megabytes, or gigabytes
The amount of storage
space the image occupies
Scanning for...
Web or Onscreen Display
72 dpi (or PPI)
24 bit or true color
Print Environment
300 dpi
24 bit or true color
then truncate palette by
converting to web format
At screen size
or dimensions
100%
At screen size
or dimensions
100%
File Size small 1x
File Size large 4x
Web =gif jpg
Print=tiff eps
Resolution
Choose the right resolution
Don’t choose higher than
you really need
If resolution is too
high...
it will take longer to render on
screen, display on the Web, or
print, and there will be no
improvement in output quality
For print 300 dpi
For web 72 dpi or (ppi)
Resolution
Choose the right resolution
Don’t choose higher than
you really need
If resolution is too
low...
too Iow a resolution will cause
a printed image to look coarse
and jagged, and its details will
be lost.
For print 300 dpi
For web 72 dpi or (ppi)