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Chapter 8. PPL3 Plus Emulation GEK-00029B
256
SIXEL GRAPHICS
The Sixel Graphics protocol provides the ability for the printer to
receive and print black and white bitmap data at various sizes to
create graphics images.
Terminology and Concepts
The bitmap data for producing a graphics image is divided into
horizontal scan lines, each of which is
six
bitmap
el
ements high. The
term for the bitmap data is
raster
. Prior to sending the data, the user
can define horizontal and vertical spacing between elements. The
smaller the spacing, the finer the grain and the higher the quality of
the image will be.
Pixels
A pixel is the logical rectangular image area defined by each bit of
graphics data that you send.
Sixel
A group of six pixels arranged vertically and sent as a group.
Grid
The positions on the page where the printer places pixels.
Pixel Aspect Ratio
The relationship between the length of the pixel to its width. For
example, a square pixel has a pixel aspect ratio of 1 to 1 (or 100 to
100). A pixel twice as high as it is wide has a pixel aspect ratio of 2 to
1 (or 200 to 100).
Pixel Spot
The actual area imaged for each pixel. The shape and size of a pixel
spot is printer-dependent and is only approximately related to grid
size.
Dot
The smallest unit that can be displayed on the printer. Several dots
may be required to represent a single pixel as a pixel-spot.
Picture Definition
The data describing the image, including grid size, pixel aspect ratio,
and the encoded raster. The picture definition does not include
formatting information, such as position or actual presentation size.
Sixel Control Codes
Within the picture definition, sixel control codes provide additional
information beyond the encoded raster, such as line breaks.