JPG, SVG, PNG, PDF: What do I use?

In the crafting world, particularly the cutting machine world, I see a lot of questions about file types. Why are there so many? Which ones are right for what I want to do? Will I ever understand the difference?

I hope I can make the differences easy to understand. I’ll focus on graphic (picture) formats suitable for cutters like Cricut and Silhoutte.

First, it helps to understand that there are two basic kinds of graphics files: Bitmap and Vector. These refer to the way it stores data.

  • Bitmaps are like mosaics: Think of the file as a giant grid of rows and columns. Each space (pixel) is assigned a color. Remember this: each little BIT is MAPped to a color. You might also hear it referred to as a raster file.
  • Vector files store elements as mathematical equations (remember back to geometry, you can graph a line with y=mx+b or a circle with r2=x2+y2?). Computers can make quick work of rendering equations, so it calculates the image from storing pieces of information: the circle’s center is at a certain coordinate, it has a specified radius, a specified interior color or pattern, and it stores the color and width of the outline (among lots of other data). Thankfully, no mathematical knowledge is required to use these files!

For our purposes, there’s a third kind of file that includes words and pictures. Think about a Word document or the PDF form you needed to print. We’ll just call this a mixed file as opposed to a graphic file. (Yes, graphic files can include text, but graphic files not used for a predominantly text editing.)

To summarize: there are three kinds of files: bitmaps, vector, and mixed. Now that we know what they are, which are the best to use?

Which is the best to use?

It depends on you want to do!

Digital cameras and some graphics programs use bitmaps. They are a predefined size measured in rows and columns of pixels. Obviously, these are best for photographic images! It’s also good for scanned images. There are also programs that can mimic using paints, markers, watercolors, and other kinds of media that can be smudged and blended.

The drawback to bitmaps is that if they are enlarged, the pixels are made bigger. Enlarge it too much and it’s easy to notice stair-stepped or blocks appearing around the edges — that’s called pixelization. Make it smaller and you can lose important detail. In other words, it doesn’t scale well. Look at the illustration, below. See how blotchy this is? It looks great as a smaller picture but the detail cannot be enlarged. If you were to want to cut this file, how would you expect the computer to figure out where the edge is to cut each flower? It’s going to guess, and it won’t guess very well. This particular photograph file will work beautifully for a print-then-cut (as long as you don’t enlarge it too much). Other subjects in bitmaps that have larger, defined expanses of color, like logos, can work quite nicely for cut files, but still can’t be enlarged too much.

Shows how bitmaps pixelate when enlarged.ate
Pixelization can happen when files are enlarged.

Scaling is where vector formats shine: since everything is calculated, you can make the scale as big or as small as you want and it will always work well. Additionally, this format was designed for manufacturing, to design extremely accurate drawings and lifelike 3D renderings (think architecture and engineering drawings). These drawings can be plotted on plotters (like the drawing feature on a Cricut or Silhouette) or they can be used on 3D printers, computer aided manufacturing machines, or in the craft world, our beloved cutting machines. They can also have gradient and pattern fills to give life-like shading to the drawing; obviously those are printed rather than cut/plotted.

A vector file scales with nice, sharp edges or perfect gradients. On the left is the smaller version. The right shows the sharp edges of the star and the gradient fill of the circle remains unpixellated as it is enlarged.

If you’re working on documents, you wouldn’t use either graphic format to store your document, but you might want to embed graphic elements of either kind into your document. The result is stored in what I’m calling a mixed formats. Typically, these are used with substantial text and are sent to printers, not plotters/cutters.

To summarize: both formats can depict realistic, shaded items or depict something with clean, sharp lines and areas of flat color. The bitmap version is comprised of squares (pixels) that require cutting software to determine the lines to cut (sometimes with lovely results, sometimes not). The vector version is wonderful for cutting perfect lines, but any gradients and patterns require printing.

About those acronyms…

Now that we know what kinds of files there are with their strengths and weaknesses, specifially what are the file types? Here are the most common standard filetypes and some comments about them to help you remember what the file types mean. There are many, many more kinds.

Bitmaps

For cutting machines, choose one of these for print-then-cut. Most cutting software can pull these in as a cut file and cut the outer shape of the graphic.

JPG Joint Photographic Expert Group. Also JPEG. (Pronounced jay-peg.) Best for photos and artwork with a high degree of variability in colors (usually created with the digital equivalent of markers, paint brushes, and watercolors). 
GIF Graphic Interchange Format. (Pronounced Jif, like the peanut butter.) Best for line art and graphics with large expanses of the same color.
PNG Portable Network Graphic. (Pronounced ping.) Like GIF, it’s best for line art and graphics with large expanses of the same color.
BMP Bitmap. Created by Microsoft, this format still exists, but isn’t used as often as GIF or PNG.
RAW Raw format, meaning unprocessed. This is usually created by digital SLR cameras (DSLR). 

Vector

These are the desired format for cutting machines. SVG is probably the most common format for home cutters, though DXF works just as well.

SVG Scalable Vector Format (developed by the World Wide Web Consortium)
DXF Drawing eXchange Format (developed by AutoDesk)
STUDIO Silhouette’s version of a cutting file. These cannot be directly read in Cricut Design Space, but they can be converted with freely available conversion packages.

Mixed Formats

PDF might be suitable for cutting/printing if it doesn’t contain lots of text, the others will not. However, you may see them available online.

PDF Portable Document Format (developed by Adobe). Whether this is possible to cut depends on the software used and what kind of data is stored within it. It can store bitmaps, vector graphics, or both. 
EPS Encapsulated PostScript (Used by Adobe Illustrator). May not be supported by cutting software.
DOC Microsoft Word format (developed by Microsoft). Usually not supported for cutting.
HTML HyperText Markup Language. Used for webpages. Usually not supported for cutting.

Other Filetypes You Might Collect

Crafters collect fonts! Here are the most common font types.

TTF TrueType Font (developed by Apple and used on all platforms)
OTF OpenType Font (developed by Adobe, Apple, and Microsoft on the TTF format). If you have a choice between the two, use this format.

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