If you're in the screen printing business or other industries that require high-quality film positives, you've likely encountered challenges when it comes to printing halftones and solid colors. This article provides a comprehensive guide to using Ghostscript for printing film positives, focusing on the Canon Pixma ix6820 printer. We'll cover the steps for different graphics software, such as Photoshop, CorelDRAW, and Illustrator. Additionally, we'll touch on some essential tips and best practices for achieving optimal results.

Printing Film Positives with Ghostscript: The Basics

Ghostscript is a versatile software tool commonly used to convert PostScript and PDF files into various formats, making it a valuable asset for screen printers. Here, we'll outline the process of creating output for different graphics software, but before diving into the specifics, ensure that Ghostscript is correctly installed and configured on your Windows machine.

Printing from Photoshop

Step 1: Prepare Your Design

• In Photoshop, finalize your design and make sure you have separated the elements into channels for halftones or solids.

Step 2: Access Print Settings

• Click "File" and select "Print."

Step 3: Choose the Printer

• Select "MS Publisher Imagesetter" as your printer. If it doesn't exist, you can add it as a pseudo-printer, specifically for creating a Postscript file for Ghostscript.

Step 4: Set Page Setup

• Configure your page setup for black and white and select the appropriate paper size (e.g., Tabloid for 11x17). Note that 13x19 corresponds to Tabloid Extra, and in Ghostscript, it's recognized as A3.

Step 5: Configure Output Settings

• Instead of color management, choose "Output" from the dropdown menu.

Step 6: Halftone Settings

• Uncheck "Use Printers Default" and select the ink that matches the channel you want to print. Set the frequency (DPI) and angle (typically 22.5 degrees) for halftone dots.

Step 7: Print to File

• Click "Print" and, if prompted, proceed with the message about image resolution being higher than 2.5. Set the printer to "MS Publisher Imagesetter" and select the 'Print to File' option.

Step 8: Define Output Location

• Specify the output location and file name, using a .prn extension for output from Photoshop.

Step 9: Repeat

• Repeat the steps above for each channel, saving each as its Postscript file (.prn file extension) to be printed using Ghostscript.

Printing from CorelDRAW

Step 1: Prepare Your Design

• In CorelDRAW, prepare your design, and ensure that you've created separate files for each color to be printed as halftones.

Step 2: Access Print Settings

• Click on "Print."

Step 3: General Settings

• In the General tab, select "Device Independent Postscript File" to allow adjustments to LPI and angle.

Step 4: Separations and Halftone Settings

• Under the Separations tab, check the "Print Separations" box and choose the color you want to print.
• Click "Advanced" and set the frequency (LPI) and angle. Choose the halftone type as "DEFAULT."

Step 5: Print to File

• Check only one color at a time, click "Print to File," create a folder if necessary, and name your file (use the .ps file extension).

Step 6: Repeat

• Repeat the process for each color, saving each as its Postscript file to be printed using Ghostscript.

LPI, Dot Shape, and Angle Recommendations

• When setting your LPI, consider your screen mesh. Multiply your LPI by 4.5 (or even 5) to determine the mesh required. For example, LPI of 45 needs a mesh of 203 or 230.
• For dot shape, ellipse is a suitable choice for color gradient transitions, but for CorelDRAW, "DEFAULT" might be necessary.
• An angle of 22.5 degrees is recommended for halftone printing, even for CMYK.

Printing Using Ghostscript

• Open GSview (a shortcut you should have created during installation).
• Click "File," "Open," and select the folder where you saved the .prn or .ps files from your graphics program.
• Double-check the orientation and media (canvas size) to match your output parameters.
• Click "Print" and adjust printer settings as needed for your Canon printer.
• If the printout appears as code text lines (gobbledygook) and not an image, select "Windows GDI printer" instead of the PostScript printer in the Print Method settings.

Additional Tips

• Consider using Postscript files for both halftones and solid colors to control inkload percentages and avoid print drivers.
• When using Adobe Illustrator, follow similar steps to those for CorelDRAW, as outlined above.

By following these steps and recommendations, you can achieve high-quality film positives with Ghostscript and your Canon Pixma ix6820 printer. Remember to share your experience and further explore our technical resources on our YouTube Channel BCH Technologies and our Tech Blog. If you're in the Greensboro, North Carolina area, feel free to visit us locally for in-depth technical assistance. Happy printing!