Color Graphics; Table 20 Color Bits Received - TransAct POSjet 1500 Programmer's Manual

Control Codes

Color Graphics

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The POSjet 1500 is a two-color printer. It is not a full color printer. A full color printer forms the various colors of
an image by mixing inks of different colors on the paper. The amount of each color determines the hue. Typically
the paper is white and no ink produces a white dot. Mixing yellow and cyan produces a red dot and mixing cyan,
magenta, and yellow in equal amounts produces a black or gray dot. If the printer has a forth cartridge, it will be
black.
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The POSjet 1500 is a two-color printer. It has white (the paper), black (an ink cartridge), and one other premixed
color (a red cartridge for example). The printer does not mix the inks on the paper. It either leaves the paper color,
prints a black dot, or a color dot. To allow the POSjet
color provides for the sending of three-color plains to the printer.
There are two ways to define colors, CMY and RGB. CMY stands for cyan, magenta, and yellow. Mixing cyan,
magenta, and yellow can be compared to blending paint. When cyan, magenta, and yellow are mixed, the result is
black. RGB stands for red, green, and blue. Mixing red, green, and blue together can be compared to blending light
beams. When the lights are turned off, everything looks black. When all the lights are on, the result is white.
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Because the POSjet 1500 Printer does not mix colors, either CMY or RGB color definitions work.
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For the POSjet 1500 Printer, RGB color definition was chosen because the colors are closer to those most often
used in print, and as a result, RGB color definition generally requires sending less data to the printer. It also turns
out to be convenient for Windows to generate data because RGB color definition is the same as the display.
The printer does not have a gray scale and cannot print various hues of color. Therefore, only two bits per pixel are
required. To allow multicolor support, three bits per pixel are available. (Compression reduces the data back to two
bits). After the data is decompressed in the printer, each dot contains three bits of information. The color print
algorithm follows.
Color Bits Received
Red Green
OFF OFF
ON ON
ON OFF
OFF ON
OFF OFF
ON ON
OFF ON
ON OFF
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The Ithaca Windows print driver provides the translation from Windows color to the three-color plains. When a
graphic is created for the POSjet
color will print black. The Ithaca
from a full color image.
(Ithaca
Page 62
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POSjet 1500
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Red
Blue Black
OFF X
ON
OFF
OFF
ON X
OFF
ON X
ON X

Table 20 Color Bits Received

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1500 Printer, the colors used must take into account that colors other than the pen
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Windows driver helps adjust the color content and generates the desired print
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Windows print driver patent pending.)
Rev M
1500 to use colors other than red, the architecture of the
Second Cartridge Color
Green
Red Black Green
X
X
X
X
X
Programmer' s Guide
Blue
Black Blue
X
X
X
X X
X X
X
Nov-07