The Ultimate Guide to Image Formats: PNG, JPG, WebP, AVIF and SVG

JPG / JPEG  Joint Photographic Experts Group

Created in 1992 by the Joint Photographic Experts Group, JPG was designed specifically to compress photographs efficiently. Its algorithm divides the image into 8×8 pixel blocks and applies the Discrete Cosine Transform (DCT) to represent each block as a combination of frequencies — discarding the high-variation frequencies the human eye notices least. The result is lossy compression: part of the original data is permanently discarded.

Why it works so well for photos: photographs have smooth, gradual color variation — exactly the kind of information JPG compresses most efficiently. A landscape photo in JPG at 80% quality can be 10× smaller than the same uncompressed file, with an imperceptible visual difference on screen.

Where it fails: the 8×8 block algorithm creates visible artifacts around sharp edges, text and areas of flat color. A black logo on a white background in JPG will show gray smudges around the letters — the famous "JPEG artifacts". JPG also doesn't support an alpha channel (transparency).

When to use it: photographs for web, print and email. Product photos, banners, blog images. Any image with lots of color variation and no need for transparency.

When to avoid it: logos, icons, screenshots with text, images with a transparent background, illustrations with sharp edges, images that will be re-edited and re-saved multiple times.

PNG  Portable Network Graphics

Created in 1996 as an alternative to GIF (which had patent restrictions), PNG uses lossless compression — no data is discarded. The DEFLATE algorithm (a combination of LZ77 and Huffman coding) reorganizes pixel data more efficiently without throwing anything away. This guarantees the decompressed image is pixel-perfect relative to the original, no matter how many times the file is saved.

The alpha channel: PNG supports a fourth channel per pixel besides RGB — the alpha channel, which controls opacity from 0 (completely transparent) to 255 (completely opaque). This allows full transparency, semi-transparency, and smoothly anti-aliased edges over any background.

PNG-8 vs PNG-24 vs PNG-32: PNG-8 uses a palette of up to 256 colors (like GIF), ideal for simple icons and images with few colors. PNG-24 uses full color (16 million) with no transparency. PNG-32 uses full color with an alpha channel — it's the most common type when people say "transparent PNG".

Where it fails: for photographs, PNG is inefficient — photo files in PNG can be 3–10× larger than the equivalent JPG. Lossless compression can't efficiently eliminate the color variation in photographs.

When to use it: logos and icons with a transparent background, screenshots with text, infographics, images with areas of flat color, digital art with sharp edges, images that need to be re-edited without cumulative loss.

When to avoid it: photographs for the web (use JPG or WebP), images that need small files, email marketing where JPG has better compatibility.

WebP  Web Picture format

Developed by Google from the VP8 video codec, WebP launched in 2010 to be the universal successor to JPG and PNG on the web. It supports both modes: lossy (based on VP8, for photos) and lossless (based on its own algorithm, for graphics). In lossy mode, WebP uses block prediction and adaptive transforms — more sophisticated techniques than JPG's DCT — to produce files 25–35% smaller with equivalent visual quality.

The best of both worlds: besides replacing JPG for photos (lossy mode), WebP also replaces PNG for logos and graphics (lossless mode with alpha channel), usually with files 20–30% smaller. It's the only format that unifies JPG's and PNG's use cases with better efficiency in both.

Compatibility in 2026: supported by Chrome, Firefox, Safari (since 14), Edge and Opera — covering over 97% of web users. The main exceptions are older email clients (especially Outlook) and legacy corporate systems running IE11.

When to use it: practically any image for the web — photos, logos, icons, banners. It's the default recommended format for any upload on modern sites. Google's PageSpeed Insights specifically recommends WebP whenever it detects JPG or PNG where WebP could be used instead.

When to avoid it: email marketing (inconsistent compatibility), print production, YouTube thumbnails (WebP isn't accepted), downloadable files that end users will open locally on older systems.

AVIF  AV1 Image File Format

AVIF is derived from the AV1 video codec (developed by the Alliance for Open Media, which includes Google, Mozilla, Netflix, Amazon and others). It's the newest and most technically advanced format available for images on the web — it produces files 20–50% smaller than WebP with equivalent visual quality in many cases, especially at lower quality settings where WebP starts showing visible artifacts.

Why it's so efficient: AV1 uses much more sophisticated compression techniques than WebP's VP8 — including intra-frame prediction modes, variable-size transforms, and loop filters. The result is particularly impressive on high-complexity photos and subtle gradients.

The encoding problem: converting images to AVIF is significantly slower than to WebP — an AVIF encoder can take 10–100× longer to process the same image. For sites with many images or build pipelines that generate image versions in real time, this computational cost matters.

Compatibility in 2026: Chrome 85+, Firefox 93+, Safari 16+. Not supported by IE11 or most email clients. Support is still lower than WebP's, and the recommendation is to serve AVIF with a fallback to WebP and JPG using the <picture> tag.

When to use it: high-traffic sites where every KB saved meaningfully impacts bandwidth cost; high-quality images where the visual difference vs. WebP is noticeable; new projects where the build pipeline already supports AVIF.

When to avoid it: when encoding time is a critical factor; for use in ImageTools' converter (the AVIF encoder via browsers' Canvas API isn't optimized and can produce files larger than the original — use server-side tools like sharp for quality AVIF).

SVG  Scalable Vector Graphics

SVG is radically different from every other format on this list. Instead of storing pixels, it stores mathematical instructions in XML — "draw a rectangle 200 wide at position X,Y in color #3ecf8e". The browser or software calculates the pixels in real time at whatever resolution is needed. A 5 KB SVG can display perfectly on a 16px favicon or on a 65-foot billboard.

Why it's the ideal format for logos and icons: logos and icons are made up of geometric shapes — rectangles, circles, bezier curves, text. SVG describes exactly those shapes with no loss of information at all. A 200px logo PNG becomes pixelated at 2000px; the same logo in SVG is perfect at any size.

Editable via CSS and JavaScript: inline SVG elements in HTML can be manipulated like any other DOM element — color changed via CSS, animations added via CSS transitions or JS, interactivity with mouse events. It's like HTML for images.

Where it fails: photographs and images with many colors and complex gradients result in huge, impractical SVGs — and even then, quality would be inferior to JPG because SVG wasn't designed to represent photographic data.

When to use it: logos, icons, geometric illustrations, data graphics, maps, any art that needs to scale to multiple sizes, interactive icons in web interfaces.

When to avoid it: photographs, images with many colors and textures, social media (most platforms don't accept SVG uploads), email marketing.

GIF  Graphics Interchange Format

Created in 1987 by CompuServe, GIF uses the LZW (Lempel-Ziv-Welch) algorithm for lossless compression — but with a fundamental limitation: it only supports 256 colors per frame. Each pixel is an index in a palette of up to 256 entries, which makes the format inefficient for photos (which have millions of colors) but suitable for simple images with few colors.

Why GIF has survived to this day: it's the only widely compatible raster format that natively supports multi-frame animations — and that trait has kept it alive decades after technically superior formats emerged. Animated WebP and animated AVIF are more efficient alternatives, but the compatibility and cultural presence of animated GIF keep it relevant.

Partial transparency: GIF only supports one "transparent" color per frame — no semi-transparency or anti-aliasing. The result is "jagged" edges around elements with curved borders, especially over colored backgrounds.

When to use it: simple animations on platforms that don't support animated WebP or MP4; animated icons with few colors; memes and social media content where the GIF format is culturally expected.

When to avoid it: static photos (use JPG or WebP), static logos (use PNG or SVG), complex web animations (use MP4 or animated WebP — much more efficient).

BMP  Bitmap

BMP is Windows' bitmap format, created by Microsoft. In most configurations, it applies no compression — each pixel is stored directly with its color value. The result is very large files: a 1920×1080 image in 24-bit BMP takes up exactly 5.93 MB, always, regardless of content.

Why it still exists: BMP has guaranteed compatibility across the whole Microsoft ecosystem — Windows, Office, printers, and legacy editing software. For internal use in image-processing pipelines where the absence of compression is an advantage (guaranteed data with no artifacts at each step), BMP still has a place.

When to use it: when a specific (especially legacy) system requires BMP; as an intermediate format in processing pipelines where compression would introduce unwanted artifacts; industrial printing on certain specific systems.

When to avoid it: any use on the web, email, social media, or any context where file size matters.