hot sun, cool air
Hello, my name is Virtua Wug.
I am a Wug, which is like a kind of thing. I have so much Virtua Fighter in my DNA that I became Virtua, too.
I am on a journey to do my very best. Will you join me?
blue sky, clear water
Friday July 10 2026 - Listening to Long Term Memory from the album Photographs.
Digital images, sometimes called raster images, are stored in various file formats which serve different important functions generally dependent on how the images are intended to be preserved and how the images are intended to be used.
I'm kind of a data hoarder, so I take image file formats seriously, maybe a little more seriously than I should. It bugs me when people store their images with inappropriate formats, so I wanted to talk a little bit about some of the most common file formats for digital images and what their use cases are like!
I'm not the most tech-savvy, so I don't know everything or even most of what there is to know about most file formats. However, I can still share what I do know.
The GIF file format is usually best suited for storing images with low resolutions and a small number of colors. The file format is probably best known for supporting animation frames. The format also supports transparent pixels, although it does not support semi-transparent pixels.
Although GIF is technically lossless, its limited color palette—up to 256 colors per frame—makes it somewhat bad for the preservation of detail. You'll often see GIF images with a ton of dithering applied to compensate for this.
GIF is widely supported across several web browsers.
Like GIF, the PNG file format supports lossless compression and transparent pixels. However, PNG supports significantly greater color depth, including semi-transparent pixels, and PNG offers superior lossless compression within indexed color images. Basically, if you store the same image as PNG and as GIF, the PNG file will usually have the higher filesize, but if the image's colors are indexed before storing as PNG and as GIF, the PNG file will usually have the lower filesize.
The more colors are used in an image, the larger its filesize will be when it is stored as PNG or most other lossless file formats. This makes PNG superb for storing images like pixel art or illustrations with few colors, but very poor for storing images like photographs except in cases where as much information as possible must be preserved.
The APNG file format is PNG's answer to animated GIFs. APNG supports PNG's color depth, semi-transparent pixels, and lossless compression, while also supporting animation frames.
PNG is widely supported across several web browsers. APNG is a little bit less widely supported, and not all image editing software plays nice with APNG.
The BMP file format is a lossless file format which preserves a lot of information, and so BMP images usually have extremely high filesizes. Where GIF and PNG's filesizes are largely dependent on the number of colors used in a given image, BMP basically behaves as though every possible color is already within the image. Two BMP images with the same resolution and the same pixel format—the number of bits per pixel—will usually have the same filesize regardless of the contents of the two images.
For most people, BMP is not a useful file format. If BMP is a useful file format for your particular needs, you probably wouldn't need this loosey-goosey introduction to file formats!
BMP is widely supported across several web browsers.
The JPEG file format is a lossy file format best suited for storing photographic images with a lot of colors.
JPEG's lossy compression can result in low filesizes for very complex images, but this compression can also seriously degrade image quality. JPEG's compression can also increase the filesizes of images with a very low number of colors; because this compression causes irreversible degradation of quality in addition to potentially worse filesizes, images with a low number of colors, especially pixel art, should almost NEVER be stored as JPEG. Seriously, just use JPEG for photos and stuff.
The above image is an animated WebP demonstrating the effects of applying lossy compression onto an image which would be better stored as a lossless file. If the image fails to load or animate, mirrors of the files are available on my MEGA archive.
JPEG is widely supported across several web browsers.
The WebP file format supports both lossless and lossy compression, transparent and semi-transparent pixels, and animation frames, making the format versatile for storing a variety of images. WebP's lossy compression is superior to JPEG's, and its lossless compression is superior to PNG's.
WebP is a superb (and in my opinion, very unfairly-maligned) file format for a variety of casual use cases, but in some more professional environments, it's not as good as other, more specialized file formats. For instance, a limitation of WebP is its strict 8-bit color space, which prevents the format from ever supporting High Dynamic Range. WebP is my personal favorite file format for images, because my use cases don't require anything WebP doesn't support and WebP filesizes are just so dang low!
WebP is widely supported across several web browsers, but some services might not play nice with animated WebP files.
Like WebP, the AVIF file format supports both lossless and lossy compression, transparent and semi-transparent pixels, and animation frames. AVIF's lossy compression is superior to JPEG or WebP's, however its lossless compression is worse than PNG or WebP's. AVIF is a contender for a replacement for the WebP format, once its adoption gets a little bit better.
AVIF support among modern browsers is improving, but it's not the best.
Like WebP and AVIF, the JPEG XL file format supports both lossless and lossy compression, transparent and semi-transparent pixels, and animation frames. JPEG XL's lossy compression is superior to JPEG and WebP's, though it's not quite as efficient as AVIF's, and its lossless compression is superior to PNG and WebP's. Alongside AVIF, JPEG XL is a contender for a replacement for the WebP format.
JPEG XL is a great format, but its current support is extremely poor. Until its adoption improves, JPEG XL's current best use cases are probably local archiving and direct filesharing.
JPEG XL is largely unsupported by modern browsers.
I probably don't need to repeat myself any more, but please, be mindful of which file format you use to store your digital images. Apply lossy compression carefully, and only onto images which are not noticeably degraded by compression artifacts. If you're trying to accommodate as many web users as possible, it's probably best to stick to GIF, PNG, and JPEG for most of your images; if you're less concerned with browser support and stuff like that, then AVIF is awesome for lossy compression, JPEG XL is awesome for lossless compression, and WebP is your jack of all trades.
The above image is an animated WebP demonstrating the different forms of compression artifacts applied by the file formats I've listed here. If the image fails to load or animate, mirrors of the files are available on my MEGA archive.