Epson PSB.2003.04.004 - Manual (Page 7)

PSB No: P-0078
Page: 2 of 3
Gamma
Function: The function that defines the light intensity ratio between the
original image and the output data. The ES-300C scanner allows
the function to be altered so that when the image is reproduced
on a different type of output device, the tones in the reproduced
images will be closer to the original image.
Grayscale: A term used to describe the output of devices that support more
than just black and white. Grayscales support up to 258 shades
of gray. The table below details the number of data bits required
to show the number of possible gray levels.
Number of Bits Possible Gray Levels
1 2 (black and white)
2 4 grays
3 8 grays
4 16 grays
5 32 grays
6 64 grays
7 128 grays
8 256
grays
Halftone: The output in 1 or 2 bit data format that simulates grayscale by
creating a pattern of small dots that vary in size and density.
Halftones are used in newspapers to display photographs. The
Epson ES-300C supports 3 types of halftoning.
Highlight: The brightest value in a continuous tone or halftone image.
Line Art: Images consisting of only black and white pixels. Text is a good
example of line art.
tine Screen: Also known as screen ruling, it is the distance between the
centers of halftone dots. For example, a newspaper uses a
typical line screen - sixty five halftone dots per inch at a forty five
degree angle for photographs.
Matrix: The square grid that forms the halftone dots. As the matrix size
increases, more possible variations on dot size and shape are
available.