XBM to WebP Converter

Encoding: the XBM uses none: bits written as hexadecimal bytes in C source; WebP uses lossy VP8 coding or lossless VP8L, and the download is a lossy WebP at the quality you choose (lossless under More options), keeping transparency.

Bit depth: 1 bit per pixel in the XBM; WebP allows 8 bits per channel, and the WebP written here has 8 bits per channel.

Colour: two colours, foreground and background in the XBM; WebP supports RGB; lossy WebP stores colour at half resolution (4:2:0), written here as 8-bit sRGB.

Metadata: the XBM can carry the #define names for width, height and an optional hotspot; WebP can carry EXIF, XMP and ICC chunks, but nothing is copied across.

XBM is the 1-bit image format of the X Window System, written as C source code so it can be compiled straight into a program. It was used for cursors, icons and window decorations, and early web browsers displayed it.

An XBM file is C code: '#define name_width 16', '#define name_height 16', optional x_hot and y_hot lines, then 'static unsigned char name_bits[] = { 0x00, ... };' with each byte holding eight pixels, least significant bit first.

XBM files usually come from X11 cursors, icons and window manager themes, and C programs that embed small bitmaps.

WebP is Google's web image format. It supports lossy and lossless compression, transparency and animation, and is typically 25 to 35 percent smaller than JPEG at the same visual quality.

A WebP is a RIFF file: 'RIFF', a length, 'WEBP', then chunks. A simple lossy file is one VP8 chunk and a lossless one is VP8L; the extended VP8X header announces alpha, animation, ICC, EXIF or XMP chunks.

WebP is the better choice for images on websites and in apps, while XBM suits X11 cursors, icons and C programs that embed bitmaps.

WebP strengths: 25-35% smaller than JPEG; Transparency and animation in one format; Supported by every modern browser. Drawbacks to weigh: Some older desktop apps and photo printers cannot open it; Max 16383 px per side.