Adding your art to the offerings of a Print on Demand company such as Zazzle or CafePress is a great way to expand the reach of your brand, gain recognition, and increase revenue from your art. So what image type should you use? The answer is, well, it all depends.
When to Use a JPG
Suppose the artwork you want to use is a full color painting. If it is small enough and doesn't have textural elements, such as heavy impasto painting, then scanning it and saving as a high quality JPG [also called a JPEG] is a good way to go. Always scan at 300 ppi or higher to get the best quality. If it is a textured piece, or too large for your scanner, you will need to photograph your piece. Again, set your camera to the largest file size available. Most cameras save pictures as JPGs. Do not use Camera Raw, as that format is not supported by either Zazzle or CafePress.
What to Expect From a JPG
When you save your art image as a JPG, you will get a complete image, with no transparent elements. If it is a painting, then that's probably going to be good. However, if it is a cut out image, then you may get unintended results.
For example, here is an image of a painting that has been saved as a JPG. You can see that it looks great printed on this t-shirt.
However, if you wanted to use an image where you wanted to follow the shape of the image as opposed to the rectangle you see above, then you would get this result from a JPEG:
While this image would look fine on a white t-shirt, on a t-shirt or other product with a colored background, the image looks like it has been plastered to the shirt, and is not the most attractive.
When to Use a PNG
Let's look at the same image, saved as a PNG with a transparent background.
PNG images can be saved with a transparent background or a fade from solid to transparent, whereas JPG images will always have a solid background that is the full size of the image.
PNG images are actually the preferred image type for Print on Demand. They preserve image quality much better than JPGs; however, all that image quality results in much larger file sizes. Make sure you consider your available storage space. If you are seeking to show your artwork in the best possible light, you will want to save it as a PNG.
Saving a JPG as a PNG is Not Enough
If you have started with a photo or a scanned image saved as a jpg, say of a drawing on a white sheet of paper, just saving it as a PNG will not "erase" the white background. Further work in an image editing program, such as Adobe Photoshop, will be necessary to convert the jpg to a png and make the background transparent.
Tutorial: Erasing a Solid White Background in Photoshop
Erasing a solid background from your image in Photoshop is easy. Use it to transform a pen and ink drawing into a very versatile image for use on a variety of products. Download this free Photoshop tutorial to get started.
Need Photoshop? No problem. I use the monthly Creative Cloud subscription that gives me Photoshop and Lightroom for just $9.99 per month. It keeps me up to date with Photoshop, and I more than make up for the subscription in my sales on Zazzle and CafePress. You can purchase other plans that also include Adobe Illustrator, InDesign, and other programs, but I find that the $9.99 bundle works well for me.