The Death of JPEG: Why it's time to move on

A legacy of blocky artifacts

The original JPEG compression algorithm relies on Discrete Cosine Transform (DCT) splitting the image into 8x8 pixel blocks. When compressed heavily, these blocks become visible, creating a "mosquito noise" effect around high-contrast edges (like text overlaying a photo).

Worse, JPEG has absolutely no support for alpha channels. If you need a transparent background, you have to use PNG, which is often massively oversized for photographic images.

The WebP takeover

Google introduced WebP in 2010. By deriving the image codec from the VP8 video format, WebP offered the best of both worlds: the transparency of a PNG and the photographic compression of a JPEG, all while being 25-30% smaller.

Today, WebP has 97%+ global browser support. There is virtually no modern web scenario where serving a standard JPEG is technically superior to serving a WebP.

AVIF and JXL: Driving the final nail

If WebP was the successor, AVIF and JPEG XL are the executioners.

• AVIF routinely beats JPEG sizes by 50% or more, while supporting HDR, 10-bit color depth, and wide color gamuts that standard JPEGs literally cannot store.
• JPEG XL was designed to replace JPEG directly. It can even take an existing `.jpg` file and re-compress it losslessly into a `.jxl` file that is 20% smaller, allowing servers to instantly upgrade billions of legacy files without generation loss.

When should you still use JPEG?

The only valid reason to output a JPEG today is for hardware and OS integration.

If you are building an app that exports images for users to open in legacy desktop software (like MS Paint on Windows 7), use as email attachments in archaic corporate Outlook clients, or transfer to digital picture frames—JPEG is still the king of backward compatibility.

But if your image is going onto a website? Convert it to WebP or AVIF.