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Finding and Using Online Images Ethically: Types of Image Files

How to find images online while following copyright law, fair use guidelines, and properly citing images.

Raster Image File Types

Raster image files: display static images, every pixel has a defined color, position, and proportion based on their resolution (i.e. 1280-720)

When finding images, the most common for web publishing is JPG (Joint Photographic Experts Group)

JPG or JPEG  .jpg
Not good for resizing
lossy compression: may reduce file size, but also reduces quality of images when saved as a smaller file.
WebP  .webp
Smaller file size – up to 35% smaller than JPEG and PNG
Not supported by all browsers and image editors
May be used if you are using Photoshop or other professional software
PNG (Portable Network Graphics)    .png
Lossless compression
Better text readability than JPG
Larger file size – do not use for high-resolution photos
TIFF (Tagged Image File Format)  .tiff
High-quality files - typically used as a lossless image format
Large file sizes (avoid using on the web; typically used for archival-quality images or for high-res print images)
 
Save your images as
JPG (smaller file size) for digital use. 
TIFF for printing larger sizes