HP manual PCL 5 Raster Images, Pixels and Pixel Encoding

zAn RGB, eight-entry palette with the following colors starting at index 0: black, red, green, yellow, blue, magenta, cyan, and white.

zA CMY, eight-entry palette with the following colors starting at index 0: white, cyan, magenta, blue, yellow, green, red and black.

•PCL Imaging mode is entered with the Configure Image Data command that creates a programmable palette of a programmed size. This palette can be programmed using the color component and set index commands.

•HP-GL/2 Imaging mode is entered when HP GL/2 mode is entered and the initialize command IN creates a programmable palette that is shared between PCL and HP-GL/2.

Any and all of the modes can be used on a page. For example, you could enter the Simple Color mode to print a headline and bar chart, PCL imaging mode to print a photographic image, and Black-and-White mode for the text on the page. Each mode is described in more detail in Chapter 2. “Using Color Modes.”

PCL 5 Raster Images

Monochrome PCL 5 raster images are made up of a series of zeros and ones. A one indicates that a black dot should be deposited, a zero indicates no dot, letting the white background show through. A one-inch wide image with a resolution of 600 dots per inch (DPI) has 600 consecutive zeros and/or ones, which represent a horizontal slice through the image starting at the left edge of the image. This slice is known as a raster row. For an image one inch high and one inch wide, at 600 dpi there are 600 hundred rows of 600 zeros and/or ones. Color raster images follow the same conventions with this major exception: the representation of a dot is changed from a single zero or one to a color specification (a pixel).

Pixels and Pixel Encoding

Raster images can be thought of as being composed of a series of pixels (picture elements). In the case of monochrome raster images, a pixel is a single bit which takes on a value of zero or one. In color images a pixel is essentially a color specification. However, there are several ways of specifying a color, and how the color is specified is called the Pixel Encoding Mode (PEM).

EN Color Printing Overview 1-7