Here’s an article about the WBMP file format.

What Is a WBMP File? A Look at the Simple Image Format That Powered Early Mobile Web

Ever encountered a file with a .wbmp extension? If you were browsing the internet on a mobile phone in the late 1990s or early 2000s, you almost certainly did, even if you didn't know it. The WBMP, or Wireless Application Protocol Bitmap (also known as Wireless Bitmap), is a simple, no-frills image format designed specifically for the limitations of that era's mobile devices.

Designed for Simplicity and Speed

The WBMP format was developed by the WAP Forum (now part of the Open Mobile Alliance) to be the standard image format for WAP sites—the early mobile web. At the time, mobile phones had small, low-resolution screens, extremely limited processing power, and connected over slow, unstable wireless networks.

Sending a full-color JPEG or even a GIF was often impractical, taking far too long to load and consuming too much data. The WBMP was the solution. Its design philosophy was built around one thing: minimal file size.

Key Characteristics of WBMP

To achieve its tiny file size, the WBMP format has a few key, defining limitations:

• Monochrome (1-bit Color): WBMP files are strictly black and white. They don't support color or even grayscale. Each pixel is represented by a single bit of data: 0 for a black pixel and 1 for a white pixel.

     

   

• No Compression: The most common type of WBMP file (Type 0) uses no compression. While this sounds inefficient, the 1-bit color depth already makes the files so small that the processing overhead of compression wasn't considered worthwhile for the simple devices handling them.

   

   

• Simple Structure: The file has a minimal header that stores basic information like the image's width and height, followed directly by the pixel data.

   

   

This simplicity meant that a WBMP image was incredibly lightweight, making it fast to transmit over slow networks and easy for basic phones to render on their screens.

The Rise and Fall of WBMP

During the WAP era, the WBMP was essential. It was used for everything from simple icons and logos on WAP portals to basic graphics in mobile "browsers." It allowed a rudimentary visual experience on devices that otherwise would have been text-only.

However, as mobile technology rapidly advanced, the WBMP's limitations became its downfall. The introduction of:

• Color screens on feature phones.

• Faster networks like 2.5G (GPRS), 3G, and beyond.

• More powerful phones that could easily handle formats like GIF, JPEG, and PNG.

...all rendered the WBMP obsolete. Modern image formats offer vastly superior quality (full color, transparency) with excellent compression, making them far more versatile even on mobile devices.

Today, the WBMP format is a relic of mobile history. You are highly unlikely to encounter it in modern web browsing. However, many modern image editing programs (like GIMP and Adobe Photoshop) and online file converters can still open, view, and convert WBMP files, preserving a small but important piece of digital heritage.