The halftone conversion that we will do in this tutorial will produce a halftone image of approximately 35 lines per inch. 35 l.p.i. dots are fairly large. However, these “big dots” produce an image that is an easy to print film positive and an easy to expose screen. You could use a screen as coarse as 155 mesh to print a 35 lpi halftone dot. However, a 180 to 205 mesh count screen coated with one light coat per side of photopolymer emulsion would be ideal. If you need a finer halftone image (45 to 65 l.p.i), you will need to use Adobe Photoshop and and an application like Wilflex EasyArt Print Halftone (Automated Photoshop Actions).
Follow the instructions carefully.
If you do so, you will see that only takes a few clicks to easily install the plug-ins into Paint.net.
Close-up of halftone image after processing...
Don't be afraid to experiment with the settings. Experiment until you have achieved the results that you are looking for.
Note that the settings indicated above are not absolute. You can make adjustments to the contrast and brightness. However, the “dot” shape is recommended as is the angle setting.
The angle setting of 26 degrees is recommended as that angle setting should minimize moire when screen printing on cloth fabric like t-shirts.
Do this by selecting Effects > Artistic > Stencil, bias: 127 (which is the default). Increasing the bias will produce a darker image. That's it, you're done!
This will convert the image into a grayscale photograph.
Select File > Open and load the image into the program.
Next go to: http://paint.net.amihotornot.com.au/Download/PluginsPack/ and download the Paint.NET Megalo Effects Plugin Pack. (download the ZIP file.)
This 500+ effects plug-in set has many useful effects that you can use in Paint.net. We are going to use two of the effects for this tutorial.
First, start the Paint.net program.
Next, open a color photograph to do a test conversion.
An image that we'll use for our tutorial can be downloaded from Microsoft free art library located here:
An ideal file would be a high resolution .tiff or .psd file, but we're going to use this low resolution .jpeg file as it is easily available as a free download, courtesy of Microsoft Office.
It's also great if you can create a halftone image without having to buy a piece of software package to do it.
In this tutorial, we going to show you how to turn a color photograph into a halftone image suitable for screen printing using the free graphics program Paint.net.
You now have a halftone image ready to printed out as a film positive for making a stencil. Inkjet film would be ideal but vellum paper can also be used as your “film.” Your goal is to have a film positive with the darkest dots possible so that exposing and washing out the screen will be easy.
A few final words…
Don't be afraid to experiment with the settings to see what effect they have on your image. Do a few sample print-outs and compare them–then choose the best results. You can always go back and start over if you don't like what you see. Also, don't be alarmed by the “grainy” image displayed on your computer screen. When you print out your film positive and hold it back at a distance of few feet, you will see that you have a decent halftone image that will be acceptable for many print projects.
If you want a complete bundled package of everything mentioned in this tutorial, order the ASPA Halftone Bundle pack. We gathered everything mentioned in this article and bundled it into one bundled zip file–available as one quick download. You'll get the latest version of Paint.net, Megalo 500+ Effects Plug-ins, a sample image to halftone, and these instructions explaining how to do the halftone conversion. It's available as download from the ASPA Store for only $5.