Printing on various materials is typically done using a flexo press. Flexo printing allows you to print on a variety of odd materials. Flexo printing requires images to be prepared properly in Photoshop, and can be rather limiting in terms of the color range of the image because of the print specifications required. If you can prepare images for flexo printing, you can prepare images for just about any other print medium.
Note: Printing on some packaging material can be done with traditional litho printing, which is how quality magazines are printed. The print quality is much better when using a litho press, but the types of materials a litho press can handle are limited.
The machines that print large format posters and billboards are typically large, specialized, and expensive. They usually print backlit posters or on fabric-based materials for use in stores, bus shelters, or billboards. The images printed on these machines need to be prepared to print well on the different materials used. Using quality profiles, if available, and properly calibrated printers can help you get fairly consistent results. However, even with the right equipment, these machines tend to print inconsistently, which makes Photoshop work a tough go with many images coming back for color adjustment tweaks until the client is satisfied.
Note: There are a few programs specifically for preparing packaging files, from companies like Barco and PackEdge, to name a few, but I still rely on Photoshop to prepare the images to feed these programs.
Many Photoshop people out there who retouch and color correct images for your average magazine, newspaper, or flyer are not prepared to handle a job for packaging. (I use the work packaging throughout this tutorial to refer to images being printed on a variety of unusual materials.)
While I have found that more and more people, agencies, and larger companies with in-house art departments may be doing their own in-house image work in Photoshop, they are ill prepared for packaging work. Packaging work is one area of the retouching world that is expanding and may hold the key to long-term retouching careers for many people, as it is still considered to be a specialized form of work.
Note: Although color correction may not be considered retouching, I have found that the bulk of my day will be spent correcting the color of my images. Regardless of how much retouching is done, the client always seems to want to make an adjustment to at least one area of an image color.
Packaging work may not be the most glamorous work out there, as it can be rather technical and not terribly creative. It isn't like working on high-end agency work, but it may guarantee you a long-term, full-time career and a well-paid position. Right now, there are few people out there who are comfortable with and have the knowledge to do packaging work properly.
I hope to cover some of the basics in this tutorial. While I will not cover all the specialized programs and substrates, I will tell you the step-by-step processes involved in a typical packaging job, which you can then apply to any situation.