Vector vs. Raster
Raster and vector are the two most common file types you’ll encounter. Learn about the key features, similarities, and differences between the two to decide when and where to use each. Most of this information is from Adobe's Raster vs Vector webpage.
Vector
Vector files are built from mathematical equations, lines, and curves with fixed points on a grid (anchor points and paths).
Infinitely scalable (no matter the size, they do not get pixelized/blurry)
Cannot smudge/blend.
While not impossible, trying to create photorealistic art as a vector file, is incredibly slow, painstaking work (example).
Smaller file sizes.
Anything that you will need to scale into different sizes, such as logos, should always be created as vector files.
File Types
.ai
.svg
.eps
.dae
.ps
.emf
.pdf (when created with a vector program)
Programs
Google Drawing
Adobe Express
Adobe Illustrator (iMac)
Adobe Fresco (iPad) (mostly Raster brushes)
Photopea (also Raster)
Raster (Bitmap)
Raster (also called bitmap) files are built from pixels. A pixel is a square with one color in it.
Can smudge/blend (and therefore can create photorealistic art)
Camera photographs are always raster files.
The more pixels an image has, the higher quality it will be and the larger the file size will be.
Important to create your file to the correct size (or larger) from the beginning so it doesn’t get pixelated if you produce larger.
File Types
.psd
.jpg
.png
.heic (heif)
.gif
.bmp
.tiff
.pdf (when created on a raster program)
Programs
Adobe Photoshop (iMac)
Procreate (iPad)
Adobe Fresco (iPad) (also has a Vector brush option)
Photopea (also Vector)
Resolution & Pixel Density (ppi)
Resolution refers to the amount of visual detail in a raster file.
Vector-only files do not have a resolution. Because you can add raster files (like images) to vector files (like in Illustrator), these vector files will have a ppi setting specifically for "Raster Effects".
Resolution/Dimension: Often the size of a digital file will be measured by the number of pixels vertically and horizontally.
Pixel Density: The number of pixels within a certain area, for example, pixels per inch (ppi) is considered the pixel density and is important to note when comparing screen quality and print quality.
Examples:
The 8th Gen iPad's screen is 1620 x 2160 px (264 ppi) vs the iPhone 14 Pro Max's screen is 2796x1290 px (460 ppi)
The 8th Gen iPad's camera is 8 MP and takes photos that are 2448 x 3264 px
Print: When creating/exporting a raster file that will be printed, it is important to set it to at least 300 ppi for a high-quality print.
When you create a "Letter" (8.5"x11") canvas with 300 ppi the resolution/dimensions would be: 2550x3300px
Digital: Most will tell you that for digital, you should export at 72 ppi (and this is important to know for the Precision Test). However, on a screen, pixels are pixels and the pixels don’t change size unless you change the resolution setting of your screen. What matters is the number of pixels in the image.