BMP24

BMP24 refers to a 24-bit bitmap image in the BMP file format, where each pixel is represented by 3 color components (red, green, blue) with 8 bits per component, totaling 24 bits per pixel. In BMP24 files, color data is stored as BGR triples rather than RGB. The format does not include an alpha channel, making it unsuitable for transparency without additional handling.

A standard BMP24 file consists of a 14-byte BITMAPFILEHEADER followed by a 40-byte BITMAPINFOHEADER, together 54 bytes of header data, then a color data area containing pixel array rows. The image data is stored bottom-up by default, meaning the first row of pixel data corresponds to the bottom row of the image; a negative height can flip the orientation to top-down. Each row is padded to a 4-byte boundary, so the number of padding bytes per row is (4 - (width * 3) % 4) % 4.

The compression method for a plain BMP24 is BI_RGB (no compression). This makes BMP24 simple and widely compatible but less space-efficient compared to compressed formats. BMP24 files typically have a .bmp extension.

Historically, BMP24 originated with Microsoft Windows as part of the Device Independent Bitmap (DIB) family. It is supported by many image editors and programming libraries, though modern applications often prefer formats with built-in compression or alpha channels (such as PNG or JPEG for photographs, or PNG for transparency).