HP 5961-0509 manual Raster Graphics

15 Raster Graphics

Introduction

A raster image is an image composed of dots. Pictures in newspapers or on television screens (also, a page printed by this printer) are examples of raster images. The PCL language includes commands for printing raster graphic images. These commands enable the LaserJet printer to receive binary data and print it as a raster image.

The binary data used to create a raster image is divided into dot rows: a row describes a one-dot-high strip of the image. Each dot position within a row is represented by a binary data bit. If a bit in a row is set to one, a dot is printed; if the bit is set to zero, no dot is printed for that position. A dot row of raster image data is transferred to the printer as a string of bytes containing a dot-per-bit representation of the row.

Figure 15-1 Binary Raster Data

Since it takes a considerable amount of data to create even a small raster image, several methods are provided to reduce the amount of data needed to define an image. (Note, that the above illustration creates a rectangle 0.013 by 0.027 inches; a binary “1“ = 1 dot = 1/300 inch.) These reduction techniques include

EN Introduction 15-1