In fact, assuming that you already have a printer (inkjet or laser) to make your film positive, your investment will be zero dollars!
The best part is that the program is totally free in cost! In addition to detailed image retouching and free-form drawing, GIMP can do image editing like resizing, editing and cropping photos and converting between different image formats. GIMP is widely considered by many to be THE free software equivalent of Adobe Photoshop, with a similar set of features and user interface.
Last time I checked, the latest full version of Photoshop was selling for around $700 (and upgrades at $200), so it’s not exactly cheap. So it’s easy to see what a great deal Gimp really is. In this tutorial, we going to a take a full color photo, convert it to grayscale and make it screen print ready by converting it into a single color halftone image using Gimp. We’ve included photos to show the steps.
It’s important to point out that this is not the best way possible for creating a halftone photo image for screen printing. Using an expensive 3rd party color separation plug-in application running through Adobe Photoshop would be a better solution if cost is not an issue. The method that we’re using here is a “quick and cheap” way to produce a usable halftone image for printing on t-shirts or other apparel.
Having said that to please the purists and experts, let’s proceed with the tutorial…
Next, convert the image to grayscale: Image > Mode> Grayscale.
First, flatten the image: Image > Flatten Image.
Next, choose Filters > Distorts > Newsprint.
“Newsprint” is the filter that will create your actual halftone.
Keep in mind that you can make the “dots” smaller or larger, depending on your equipment and printing requirements.
Now, the only thing left to do is printing out your finished image. Printing out your image is easy, because we now have a simple 1 color, black and white bitmap image. We recommend that you adjust your inkjet or laser printer output settings to print at the darkest level possible when printing your film positive. Moreover, you will achieve a better result if you are able to print with an inkjet printer using inkjet film designed for creating film positives.
Most screen print supply vendors sell this type of inkjet film and it works great. If you use vellum paper designed for laser printers, it would be a good idea to spray your printed film positive with a toner darkener spray to make the “dots” as dark as possible. This type of spray (and laser vellum paper) are also available at most screen print supply vendors.
For best results for screen printing the halftone images created using this tutorial would be to use mesh counts of 195 to 230, coated with a pure photopolymer emulsion of just 1 light coat per side. An exposure unit with a metal halide lamp or other similar high UV light source would be best for exposing your screens. Because the dots can be made as large as necessary, lower mesh counts and a lower quality light source (halogen or fluorescent) lights could also be used. Have fun with Gimp and halftones!
P.S. Would you like to see another easy way to create a halftone image for screen printing? Check out our tutorial: How to Create a Halftone Image for Screen Printing-Fast, Easy and Free.