PSB No: P-0078

 

 

 

 

 

 

Page: 2 of 3

Gamma

The function that defines the light intensity ratio between the

Function:

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.