In the crafting world, particularly the cutting machine and the sublimation worlds, 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 Silhouette as well as printed crafts like print-then-cut, sublimation, and digital paper.
Bitmap vs. Vector
First, 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 completeness, 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 don’t work well for long-format text).
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! Each of these graphics formats has their strength and weaknesses. Read on to find out more.
Raster, aka Bitmap files (JPG, PNG, GIF, BMP, RAW, etc.)
Raster files are a matrix of pixels in a predefined grid. Digital cameras take pictures in raster images (usually JPG), images are usually scanned into raster files, and there are tons of programs that work in raster format (Microsoft Paint, GIMP, Adobe Photoshop, Corel PaintShop Pro, and any photo editor, for example). They earn the moniker “bitmap” because each bit (pixel) is mapped to a color for each position in the grid. Bitmaps can hold large, detailed images, like from the Webb telescope, a from the most powerful microscope, or whatever photos are on your camera. They can also have minimal detail, like an emoji, clip art, or even a simple, single color symbol like an arrow.
The file size is usually the width (in pixels) x the height (in pixels) x a certain number of bytes representing the color of the pixel. A “small” photograph is 1024×768 (I use quotes, because, at one time in the not-THAT-distant past, these were amazingly large!), so even without any color data, that’s 786,432 pixels that need to be stored. A 12MP picture, which your phone is probably quite capable of, is 4032×3024 pixels, or 12.6 million pixels. These files get HUGE. What differentiates these different formats is the kind of compression algorithm they use.
- JPEG/JPG: This is a format developed the Joint Photographic Experts Group. It is a lossy format (it does lose a bit of information) which removes tiny details that the human eye doesn’t perceive and then breaks the image into small grids of pixels and applies a lot of math. This makes file sizes very small. This works great on detailed photographs, where it can brighten or darken a few pixels here and there that won’t be noticed by the human eye, but because of how it’s encoded, the file size is substantially smaller.. It is not good for text or line art, as the grids of pixels and the math can actually introduce small artifacts, making the sharp lines seem a little fuzzy.
- GIF: This Graphic Interchange Format is quite useful for animations (which can’t be printed or cut!), but it can be a single, unanimated image, too. This is a lossless format, meaning no information is lost. However, it uses a finite palette of colors and uses a shorthand notation to make the files smaller. Imagine describing the first line of the matrix as: 600 pixels of color 1, 50 pixels of color 2, 50 pixels of color 3, 300 pixels of color 1. The shorthand for describing groups of pixels can make quite compact files this way, but if there are a lot of changes in colors (like a photograph where there are few pixels that are exactly the same color AND there are more than 127 colors), there isn’t any savings. This format is designed for line art where there are large expanses of the same colors as well as a limited color palette.
- PNG: The Portable Network Format is also a lossless format, and uses a shorthand to describe all the colors similar to a GIF file. It does not limit the color palette, though. It’s real claim to fame, though, is that it can have a transparent background. If a detailed image (like a photograph) is used, the space savings aren’t all that great, but it doesn’t lose a single pixel, either. In fact, an image like a photograph can actually be larger than a JPG and the differences when viewing or printing files is negligible and likely noticed only by someone trained to look for the differences. PNG files won’t get artifacts around text or sharp edges UNLESS it’s from a converted JPG file with artifacts, in which case it preserves every pixel, including the artifacts.
- BMP: This early BitMaP file format is does not have compression. This isn’t a common format anymore, but there are a lot of legacy graphics out there that are still very useful. They can be converted to other formats easily or simply used as-is. Many times these are for clip art or line art styles of graphics that are intentionally small, like 640×480 or less, since their file sizes are so large.
- RAW: This lossless format uses absolutely no compression. Prized by professional photographers, every pixel is accounted for and the file sizes can be huge. DSLR cameras will store in RAW format, as will many cell phones. Typically, though, RAW is manipulated by the photographer or editor, then exported in it’s finished form to another compressed format.
Which one is better? Oh, obviously RAW, since you get every pixel. Except their files are HUGE and take forever to load. Maybe PNG is better, because you get transparent backgrounds. But it’s terribly inefficient for photographs. So JPG is better, right? Except it drops artifacts around text and clean lines in line art styles. Hmmm…looks like there’s no “best.” More like selecting the best format for the type of image.
Drawbacks to Raster Graphics
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. Put another way, 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 too much. If you’re using these for printed crafts, the picture of the cake would print well as long as you don’t enlarge the file too much.
Other kinds of images in bitmaps that have larger, defined expanses of color, like logos. This is the line art style. Not only can these print nicely (as long as they aren’t scaled to large or too small), they also have nice, defined edges that can be traced without too much error so cutters can cut them nicely.
Scalable Vector Format, or SVG
It’s right there in its name: Scalable Vector Graphics are designed to scale to be very large or very small without pixelating or getting indecipherable. 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), printed on 3D printers, used in CAD/CAM machines, or in the craft world, our beloved cutting machines and laser cutters. They can also have gradient and pattern fills to give life-like shading to the drawing; obviously those are printed rather than cut/plotted.
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. Mixed formats include PDF (Adobe’s Portable Document Format), EPS (Encapsulated PostScript), and others.
Both raster and vector formats can depict realistic, shaded items or depict something with clean, sharp lines and areas of flat color.
Raster formats, comprised of squares (pixels), are great for crafting that is printed. It can be converted from jagged squares to a vector format for cutting, sometimes with lovely results, sometimes not.
The vector formats are wonderful for cutting perfect lines. Vector formats can also contain colors, gradients, and patterns and can scale magnificently for printing.
About those acronyms…
Now that we know what kinds of files there are with their strengths and weaknesses, specifically 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.
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).|
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.|
|AI||Adobe Illustrator, a proprietary format developed by Adobe.|
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.
|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. Depending on the content, it can be used for sublimation.|
|EPS||Encapsulated PostScript (Used by Adobe Illustrator). May not be supported by cutting software. Possible uses for sublimation.|
|DOC||Microsoft Word format (developed by Microsoft). Usually not supported for cutting but can be used to size and print many files for sublimation.|
|HTML||HyperText Markup Language. Used for webpages. Usually not supported for cutting, marginal use for sublimation.|
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.|
Updated on 7/21/2023. To read more about file formats specifically for sublimation, see JPG, SVG, PNG, PDF: What do I use?