More often than not, a customer will supply you with artwork that depicts the image exactly as they want it to be printed on the shirt. That is, a white (or other colored) image on a black background. Keep in mind that we are talking about strictly a one color (or grayscale photo) print on a black shirt.
To convert an image like this into a camera ready film positive is very easy.
Simply convert the image into a black and white or grayscale bitmap and “invert” it using a bitmap editor. This resultant image will be what you will use to make your film positive—a black on white “wrong reading” image. See the example.
A more complicated inversion process will be required when a customer supplies you with a black on white image and wants that image printed with white ink (or other color) on a black shirt. The simple inversion process will not work here. What you will end up having is an image that will produce a print result with the “x-ray” effect.
Preparing art like this is somewhat more complicated. See below for an example.
To convert the artwork so you will have a “correctly inverted” film positive, you will need to create an “underbase” of black for the image and then position the art on top of the black underbase and finally invert that composited image.
Converting black and white art to make it print ready for black shirts can sometimes be confusing and difficult. Take your time and check it over thoroughly as mistakes can easily be made. After you have done a few of these conversions it will become much easier.
The content of this article is an excerpt from the ASPA training course The Secrets of Printing T-Shirts and How to Make Big Money!