Let's talk basics first. They are two types of image files. Vector and Bitmapped.
Vector files are usually:
.ai: Short for Adobe Illustrator
.eps: Encapsulated PostScript is an older type of vector graphics file. .eps files don’t support transparency in the way more modern file formats like .ai do.
.pdf: The Portable Document Format is built for the exchange of documents across platforms and is editable in Adobe Acrobat
.svg: The Scalable Vector Graphics format is based in XML (a markup language used widely across the Internet that's readable by both machines and humans). It’s useful for the web, where it can be indexed, searched, and scripted.
The magic of a vector file is that it is all math and can be scaled to any size with no loss of quality.
Logos are often created as vector files. But it is tough to create an image with a vector file. But the great thing about vector files is that you can print them at any size and the quality is always great. Vector files are not restricted by size.
A Bitmapped file can come in many flavours as well.
PNG, EXIF, BMP, JPEG and TIFF are the main ones.
The challenges with bitmap file types are many...
- They are much larger as they need to store all the pixels for the image.
- If they do not have enough pixels then the image will look soft and pixelated.
Photographs are normally bitmapped images. Below is what a low-resolution image looks like when scaled up beyond the needed pixels to make it look natural.
The more pixels the more detail and Bitmapped images are calculated in PP! or Pixels per inch. A few rules that we use for Bitmapped images.
- The farther away you are viewing the image, the lower the resolution can be. Think of a billboard. They are printed at a very low resolution. If you look at a billboard up close you can count the dots. But when you are 30 feet away our eyes aren't strong enough to see the low resolution and the image looks great.
- For every meter you move away from the print, you can cut the resolution in half.
- You can usually find the pixels for your image by going to the file properties on a PC or Get Info on a Mac.
In some cases you can add resolution to an image, new programs are coming out that use Ai to fill in the pixels. Our test shows that it does a great job on images that are high quality to start but lack resolution.
We like to have at least 150 PPI at the final print size.