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Common UNIX Printing System Sweet phần 7

Các thuộc tính cupsBitsPerColor quy định cụ thể bao nhiêu bit được thông qua để trình điều khiển cho mỗi màu. Sử dụng một lệnh setpagedevice PostScript để thiết lập thuộc tính này cho các tùy chọn: setpagedevice bit là số bit mà bạn muốn: 1 hoặc 8. Bạn có thể thêm lệnh này đến một tùy chọn có sẵn, tuy nhiên các đặc điểm kỹ thuật PPD bao gồm một lựa chọn BitsPerPixel đặc biệt phù hợp | previous page page_362 next page Page 362 The cupsBitsPerColor attribute specifies how many bits are passed to the driver for each color. Use a PostScript setpagedevice command to set this attribute for the options cupsBitsPerColor b ts setpagedevice where bits is the number of bits you want 1 or 8. You could add this command to an existing option however the PPD specification includes a BitsPerPixel option that is specifically suited to the task. The option looks like the following in each PPD file OpenUI BitsPerPixel Output Quality PickOne OrderDependency 10 AnySetup BitsPerPixel DefaultBitsPerPixel 8 BitsPerPixel 1 Draft cupsBitPerColor 1 setpagedevice BitsPerPixel 8 High cupsBitsPerColor 8 setpagedevice CloseUI BitsPerPixel Add this option to both the laserjet.ppdand deskjet.ppd files to enable the dithering code. Installing the New HP-PCL Raster Driver To install the new driver start by copying the rastertohp filter to the CUPS filter directory cp rastertohp usr lib cups filter ENTER Then copy the PPD files to the model directory cp .ppd usr share cups model ENTER Finally re-add any HP printers to use these new PPD files with the following command lpadmin -p name -m filename.ppd ENTER Summary CUPS printer drivers are composed of a PPD file and one or more filter programs specifically for the printer. PostScript printers can use the standard CUPS filters and do not need additional filter programs to drive them. Non-PostScript printers generally have a raster filter and may also provide text HP-GL 2 PDF and other types of filters for various file formats. The text filter presented in this chapter shows how a printer driver can provide accelerated printing for specific types of files. Ditheringalgorithms enable a printer driver to provide higher quality output than the basic raster filters support. The dithering algorithm presented in this chapter shows how to add dithering to printer drivers without a lot of work. previous page page_362 next page previous page