Image Formats

There are many image file formats in the world. The ones listed below are generally recognized as usable on the Web, although BMP is generally not recommended as browser support is potentially constrained; it should usually be avoided for web content.

While it is not especially important that a web crawler can support image formats, the examples below are provided for completeness. Note that as not all browsers support all common formats, some images may not display below in the browser you are using to view this page.

File format MIME type File extension(s) Sample
Animated Portable Network Graphics image/apng .apng
AV1 Image File Format image/avif .avif
Bitmap file image/bmp .bmp
Graphics Interchange Format image/gif .gif
Microsoft Icon image/x-icon .ico, .cur
Joint Photographic Expert Group image image/jpeg .jpg, .jpeg, .jfif, .pjpeg, .pjp
Portable Network Graphics image/png .png
Scalable Vector Graphics image/svg+xml .svg
Tagged Image File Format image/tiff .tif, .tiff
Web Picture format image/webp .webp

File Sizes

Ignoring quality levels, each format also has quite different file sizes - the table below shows an example image saved in each format. These examples are for illustrative purposes only, while I used a resized version of the same source photograph for each image, default save settings were used and I didn't investigate any optimisation settings. Some files also have EXIF or other image metadata which affect the final file size. With that said, the AVIF and WebP formats seem to be the best in regards to size and something worth keeping an eye on as more software packages support these formats.

Format Size
JPEG XL 31.1 KB (31,948 bytes)
WebP 37.0 KB (37,972 bytes)
AVIF 98.7 KB (101,141 bytes)
JPEG 111 KB (114,263 bytes)
GIF 261 KB (268,202 bytes)
PNG 682 KB (699,212 bytes)
TIFF 878 KB (899,752 bytes)
BMP 1.78 MB (1,870,230 bytes)

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