Good Raster, Bad Raster

What is the difference?

Often times we get a request to print a file that, well, just will not print very good.  Turns out the customer found an image on the internet and thought it would make cool shirt.

The problem with this is two fold.  First, this is someone else’s artwork and second, the image quality is of poor resolution.

What is poor resolution?

I’m sure the image started out as a high resolution image.  But web images are of low resolution and typically small in size.  So in theory you have two things working against you.  A low  resolution image (72 dpi) and a small size (usually 1 or 2 inches).  If you blow this up to t-shirt size art, it’s just not very good quality.

Okay, I’ll just increase the resolution they say.  Not so fast my friend.  Just increasing the resolution and image size doesn’t really do anything at this point.  You see, it is easy to reduce the image size, but you can’t just increase the image size.

For instance, let’s say you have a 72dpi image.  That means 72 dots (really squares) per inch in either direction. If you increase the dpi to 144 you now have 4 squares for every one square you had before.  So in theory your resolution hasn’t changed at all. And every time you double the size of the image, the resolution gets cut in half.