BMP to PGM Converter

BMP (Bitmap) is a raster image file format developed by Microsoft for the Windows operating system, introduced with Windows 3.0 in 1990. The format stores pixel data in a straightforward structure: a file header specifying dimensions, color depth, and compression method, followed by an optional color palette and then the raw pixel array. BMP supports color depths from 1-bit monochrome through 4-bit and 8-bit indexed color to 16-bit, 24-bit true color, and 32-bit with alpha channel. Most BMP files store pixels uncompressed (BI_RGB), though optional RLE compression is available for 4-bit and 8-bit modes. Pixels are arranged in bottom-up row order by default, with each row padded to a 4-byte boundary. One advantage is absolute simplicity — the format has no complex encoding, filtering, or compression layers, making BMP files trivial to read and write programmatically in any language. This simplicity also means BMP images render with zero decoding overhead, useful in scenarios where decompression latency matters. The format's deep Windows integration is another strength: BMP is the native bitmap format for Windows GDI, clipboard operations, and device-independent bitmap (DIB) handling, ensuring first-class support across the entire Windows ecosystem. While BMP's lack of compression produces large files unsuitable for web use or storage-constrained environments, it remains widely used as an intermediate format in image processing, as a clipboard exchange format, and in embedded systems where decoding simplicity outweighs file size.