How to print with Gimp-Print in Mac OS X (10.2 and later)By Tyler Blessing with Robert Krawitz and Andy Stewart

Notes: The example images shown in this document may look slightly different than those displayed on your Mac."Print Center" is called "Printer Setup Utility" in Mac OS X Panther.

Setting up a USB Printer

Before proceeding, make sure your USB printer is turned on and properly connected to your Mac with a known-good USB cable. If you are having problems using a parallel-to-USB converter cable, try using a different brand or consider the network setup option described later in this document.

1) Launch Print Center (located in /Applications/Utilities/). Next, hold down the keyboard option key and either click on the Add button in the toolbar or select Add printer... from the Printers menu in the menubar. A printer set-up sheet will open.

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2) Click on the top pop-up in the set-up sheet and select Advanced.

Note: you will not see the Advanced menu item if you didn't hold down the option key in step 1!

3) Click on the Device pop-up and select your printer's name from the bottom of the list.

Note: if you see only USB Printer (usb) and not your printer's name in the list then you either have a bad USB connection or else you need to reset the print spooler. First, make sure that your printer is turned on and properly connected, then go to the Sharing pane of System Preferences and click the checkbox for Printer Sharing; changing this setting will reset the print spooler. As far as setting up a USB printer is concerned it does not matter whether Printer Sharing is turned on or off, it is the act of turning it on or off that resets the spooler. When you have finished return to step 1 and begin again.

When you select your printer the Device Name and Device URI fields will be filled in for you automatically. You may change the Device Name now if you wish (this is the name displayed for this printer in the Print Center Printer List and in application print sheets). Do not change Device URI.

4) Click on the Printer Model popup and select your printer's manufacturer; then select the correct driver for your printer in the Name browser. Please note that Gimp-Print supports hundreds of printers and many have similar names or model numbers ... be careful to select the correct driver!

5) Click Add to complete the setup.

Finished! Your printer will now appear in the Print Center Printer List and in application print sheets.

Network Printing with Gimp-Print

You can make almost any Gimp-Print supported printer available to multiple computers on a network by using an inexpensive parallel-port-to-ethernet print server. Additionally, many popular 802.11b wireless routers include a built-in parallel-port print server that works well for this purpose.

If your printer is supported by Gimp-Print and it is available over TCP/IP via a built-in network card (such as the Epson 10/100 ethernet type-b card available for certain printers) or via an inexpensive network print server (as described above) then you can set up your printer for IP printing with Gimp-Print:

1) First you need to get the IP address and Queue Name for your printer (or print server) from your network administrator . If you are the administrator for your network consult the documentation that came with your network device to learn how to determine this information. If you can't determine the Queue Name for your print server try using the default queue first. If that fails try a common queue name like lp (lower case LP). If you don't use the correct queue name you won't print.

2) Open the Print Center utility (located in /Applications/Utilities/) and click the Add button in the Print Center toolbar, or select Add printer... from the Printers menu. A printer set-up sheet will open.

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3) Click on the popup at the top of the sheet and select IP Printing.

4) Fill in the Printer's Address and Queue Name in the appropriate boxes.

5) Click on the Printer Model popup and select your printer's manufacturer; then select the correct PPD for your printer in the Model Name browser. Please note that Gimp-Print supports hundreds of printers and many have similar names or model numbers ... be careful to select the correct driver!

6) Click Add to complete the setup.

That's it! Your printer will now appear in the Print Center Printer List and in application print sheets.

7) (Optional) If you want to give your network printer a more descriptive name select it in the Printer List window and choose Show Info from the Printers menu to open the Printer Info window.

Within the Printer Info window you can change the Printer Name & Location, select a different Printer Model or configure your printer's Installable Options.

To change the name displayed in the Printer List (and print sheets), choose Name & Location.

Modify the Printer Name and Location data as appropriate, then click Apply Changes.

Changes you make in the Printer Info window take effect immediately.

Changing settings while printing

In any print sheet, switch to the Printer Features panel to see the options available for your device.

Be sure to look through all of the Feature Sets if Basic Settings doesn't show you all of the options you expect to see.

Media Type

Most inkjets support printing to a wide variety of media, such as plain paper, photo-quality inkjet paper, glossy paper, and plastic transparencies, just to name a few, and the surface characteristics of these differing media types vary widely. Producing high quality printed output on each surface requires printing with a specific density of ink. The Media Type setting affects the density of ink deposited by the printer. Each setting is optimized for the specific combination of printer and media type, and the available choices will vary according to printer model.

Resolution

Inkjet and laser printers produce images by "weaving" together very large numbers of very small dots, much in the same way that an artistic painter produces a painting by combining a large number of small brush strokes. When the tiny dots comprising an image are spaced very close together on a continuous visual surface, the human brain interprets the entire pattern as a single image, rather than a large collection of tiny dots. In general, smaller dots that are more tightly spaced together produce a more realistic effect.

With regard to printers, the term Resolution refers to the number of distinct dots that a printer can produce in a given dimension. For example, a resolution setting of 360 DPI means that the printer can produce 360 distinct Dots Per Inch of linear output. When a compound resolution is given, the first number indicates the horizontal resolution (the direction parallel to the printer's roller axis), while the second number indicates the vertical resolution. When the vertical resolution is not listed it should be assumed to be the same as the horizontal resolution.

Most printers support printing at multiple resolutions, and many printers support various quality options at each resolution. The Gimp-Print driver attempts to offer every resolution supported by the printer hardware. In general, the lowest quality resolution option is listed at the top of the selection menu. Moving down the list, each successive option provides increasingly higher output quality, as well as increasingly longer output time. Typically, resolutions below 300 DPI are useful only for high-speed draft printing, while resolutions above 720 will produce photo-quality output. High resolution output can require substantial driver processing time, and substantial amounts of memory and disk space; it's not uncommon for a full page, 1440x720 DPI image to require 100 MB of temporary storage!

UnidirectionalAs the head of an inkjet printer moves back an forth across the page, ink may be deposited in both directions. The Unidirectional setting forces the driver to place ink on the page during only one direction of movement; the print head deposits no ink on the return pass. For many printers, this setting increases

the print quality, but at the cost of a near doubling in print time.

High Quality and Highest QualityStandard print modes may produce an undesirable effect called banding where the printed image looks like it has rows of stripes with a small separation between the stripes. This output defect is caused by very small non-uniformities in the nozzles of the print head. In the High Quality and Highest Quality quality modes, the printer will make mulitple passes over the same part of the page using different nozzles on the print head for each pass. This oversampling technique virtually eliminates banding, at the cost of more temporary disk space and reduced print speed (owing to the multiple passes), but it does not require significantly more processing time in the driver.

MicroweaveCertain older model Epson printers support a printing mode called Microweave, which uses special logic within the printer to improve the print quality. At a given DPI, Microweave print modes will usually produce better quality output than non-Microweave modes, with only a small performance penalty. Even for supported printers, Microweave is not available at all resolutions.

DMTDMT, or Dot Modulation Technology, refers to a print mode used by certain Canon printers which improves the quality of the printed output. Unfortunately, at this time, not all of the available DMT modes work correctly. The cases which do work correctly will offer significantly improved printing quality.

Image Type

Line Art: This setting tells the printer driver to generate color quickly. The color is bold and bright, but color accuracy is not very good. There may also be some unexpectedly sharp transitions in colors. This mode is acceptable for printing text with small amounts of color, and may be acceptable for presentation graphics.

Solid Colors: This mode produces color which is considerably more accurate than the Line Art mode, but with a reduction in performance. In general, hues will be accurate but tonalities may not be accurate. There should be no sharp transitions in colors. This mode is good for printing presentation graphics in most cases.

Photograph: This mode produces the most accurate colors and tonalities at a greater cost in performance. This is the mode to use when printing high quality photographs or other high quality images.

Dither Algorithm

Adaptive Hybrid: the default dithering algorithm, it produces the highest quality for most types of output. When using this algorithm the driver analyzes the entire image and selectively switches between ordered dithering and Hybrid Floyd-Steinberg (in dark regions), depending upon the image characteristics.

Ordered: a pure ordered dither that generally yields excellent quality for simple black and white or four-color printers that lack advanced features such as variable drop size or drop modulation. Ordered is not optimized for printing text or very fine details (certain kinds of line art), particularly at high resolutions, and it is not recommended for use with six-color printers if high quality output is desired. Ordered is less processor intensive than Adaptive Hybrid.

Fast: a pure ordered dither with a very simple black-to-color transfer model. It is substantially less processor intensive than Ordered, but for most printers the output quality is generally much worse, with the exception being simple four color printers, three color printers (CMY), and monochrome laser printers.

Very Fast: similar to Fast, but with a very simple dither matrix that produces a strong diagonal pattern effect, which may be useful for some purposes. For pure black and white images dominated by horizontal and vertical lines, and for most types of output on monochrome laser printers, this algorithm may actually yield the best results. For most other cases, this algorithm will produce low quality output.

Hybrid Floyd-Steinberg: a modified Floyd-Steinberg error diffusion algorithm. This algorithm is slow and generally produces the worst results; its use is not recommended for any purpose! Error diffusion algorithms can render very fine detail, and generally perform very well at high densities, but tend to produce noticeable artifacts in pale image regions. Additionally, pale image areas immediately adjacent to white must accumulate sufficient error before any dots are printed. This effect, often called waterfalling or tearing, produces a jagged edge.

Eventone: an advanced error diffusion algorithm that produces extremely smooth, uniform regions of solid color, and extremely crisp fine black lines. At very high resolutions, the smoothness of this algorithm is superior to Adaptive Hybrid, particularly on six color printers. This algorithm currently exhibits slight waterfalling in very pale regions, some noise and artifacts in the midtones, and may produce a sheen effect in very dark regions. Eventone is the most processor intensive algorithm, but in many cases it produces the best results, and is recommended for the highest quality photo printing. This algorithm is experimental and may change.

Ink Type

Most printers offer the user a choice of printing with various combinations of installed ink cartridges. Many Canon, Lexmark, and HP printers support various combinations of cartridges, such as black only, black and color, photo color, and so forth. Most Epson printers let you choose between Four Color Standard printing (CMYK) and Three Color Composite (CMY), which uses a combination of CMY to produce a "composite" black. In contrast to many early color inkjets that lacked a black ink cartridge and produced a grainy and greenish composite black, modern Epson printers produce a very rich black when printing in three-color composite mode. In fact, when printing on certain special papers, such as Premium Glossy Photo Paper and Premium Semigloss, the Epson Stylus C70 and C80 (and derivatives of these printers) will produce higher quality output using Three Color Composite mode rather than Four Color Standard. Due to differences in ink formulation between the black and color inks, the black ink doesn't adhere properly to the paper surface (Epson's own proprietary drivers print in this mode on these special papers).

Output Mode

Color is the default output mode. The driver will convert the input color (typically RGB) into the printer's output color mode, which is user selectable via the Ink Type setting. Grayscale: this setting will cause a color image to print in various shades of gray, although the printer may use mixtures of color ink to produce the gray shades.

Black & White: forces a color printer to print with only black ink, which may reduce output time on certain printers.

Raw CMYK: the driver will attempt to translate an input CMYK file directly to CMYK output on the printer.

In most cases, expert adjustments should not be necessary, or should be performed in image editing software rather than within the driver. The most common use of these adjustments would be to compensate for experimental printing conditions, such as using a development driver that is not fully optimized.

Brightness: changes the endpoints of the input-output curve, but does not change the curve shape. values less than 1.0 produce grayish whites and black shadows, while values greater than 1.0 produce grayish blacks and white highlights.

Contrast: A setting of 0.0 gives a solid gray for the entire image, the exact gray depending upon the brightness chosen.

Gamma: adjusting the Gamma value changes the shape of the input-output curve, but does not change the curve endpoints. Gamma values less than 1.0 will result in a darker image, while values greater than

1.0 will result in a lighter image.

Density: controls the amount of ink deposited on the paper. If you have chosen the correct media type but ink is bleeding through the paper or puddling, try reducing the density to the lowest value that produces solid black. If solid blacks do not print as solid black, even with the Contrast and Brightness at 1.0, try increasing the Density.

Saturation: controls the brilliance of colors. Values less than 1.0 produces muted colors, while values greater than 1.0 produce exaggerated colors. A value of 0.0 produces pure grayscale. Very high saturation values can produce unexpected effects resembling posterization or banding.

Cyan, Magenta, YellowThese three settings permit independent adjustment of the output levels for cyan, magenta, and yellow. Normally, the default values should produce a neutral gray, but tweaking one or more of these settings can produce interesting effects.

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