Images
File Formats
File Format |
Features |
Use for... |
Don't use for... |
| JPG | Raster; lossy compression (small file sizes but loses quality) | Photos and artwork- online and printed | Transparent web graphics |
| PNG |
Raster; lossless compression; allows transparent background |
High quality transparent web graphics, such as logos, charts and icons | Photos |
| GIF |
Raster; lossy compression, small files, limited colors |
Animated web graphics | Printed graphics |
| TIFF |
Raster; very large files, uncompressed, detailed image data |
High quality print graphics, high quality scans | Web graphics |
| Vector; preserves formatting | Printing, displaying web documents | Editing designs |
More information: Image file formats: when to use each type (99designs blog).
Raster vs. Vector
Raster images (.jpg, .gif, .png, .tif.) are comprised of pixels. If you enlarge a raster image too much, it will be blurry and pixelated.
Vector images (.ai, .eps, .pdf, .svg) are comprised of paths. They stay sharp and crisp regardless of how they are resized.
Compression
Lossy compression creates small file sizes, but loses quality at higher compression ratios.
Lossless compression does not create a loss of quality, but file sizes are larger than lossy compression.
Image Size and Resolution
Image size refers to the dimensions of the image in pixels. For example, a 3x5 inch image translates to 300 x 500 pixels.
Image resolution is measured in dpi (dots per inch) or ppi (pixels per inch).
Screens have a resolution of 72ppi, so if you are creating digital graphics, you don't need a higher resolution than 72ppi.
High quality printing prints at 300dpi.
Image Warping
If you need to change the size of your image, make sure to keep the dimensions proportional. Squishing or stretching your images can make your work look less polished.
It depends on the software you are using, but you can lock the proportions so that you don't warp your images when changing the size. Often holding the shift key while changing the size will lock the proportions.
Find Images
- UnsplashFree, high resolution images that do not require permission to use. Attribution is not required but encouraged.
- Creative Commons Image SearchSearch for Creative Commons licensed images through a variety of sites, including Google Images, Flickr, and Wikimedia Commons, and use the content in your own multimedia projects.
- Google ImagesOn the results page, go to tools > usage rights and select different licenses.
- Flickr: Creative CommonsMany Flickr users have chosen to offer their work under a Creative Commons license. Browse or search through the content under each type of license.
- PixabayPixabay has images, video, illustrations and vector graphics that are made available under the Pixabay license. You can use the content for free, for commerical and non-commerical projects, and attribution is not required, but encouraged.
- PexelsFree, high resolution images that do not require permission to use. Attribution is not required but encouraged.
- Noun ProjectOver a million curated icons; available under Creative Commons attribution license.
- Multicolr search by TinEyeUse this tool to find images that contain certain colors; create a palette of up to five colors to search.
- Disabled and Here collectionThis collection is a disability-led effort to provide free and inclusive stock photos shot from our own perspective, featuring disabled BIPOC (Black, Indigenous, People of Color) across the Pacific Northwest.
- Nappy"Beautiful photos of Black and Brown people, for free." All images licensed under CC0. Attribution not required but appreciated.
- Digital Public Library of AmericaA database of images, texts, videos, and sounds from libraries, universities, and museums, with some material holding creative commons licenses or material that is in the public domain.
- Library of Congress Digital CollectionsFreely available digitized materials from the Library of Congress, including the collections formerly called American Memory. Change the area that you are searching under to the Prints & Photographs Division.