device independent bitmap

(DIB) An image format in which the sequence and depth of pixels in the file is not specifically related to their layout in any particular device. This allows any device dependent bitmap (DDB) image to be converted to or DIB format without loss of information, and this can then later be converted to other DDB formats for, e.g., printing or display. Rather than requiring converters from each DDB format to all other formats, only converters to and from DIB are needed.

DIB images are normally transferred in metafiles, bmp files, and the clipboard.

Transferring colour bitmaps from one device to another was not possible in versions of Microsoft Windows earlier than 3.0. Application programs can build DIB images without any interaction with Windows. If Windows lacks a drawing primitive, the application can simulate it directly into the DIB instead of using the existing graphics device interface (GDI) primitives. Unfortunately, under Windows versions 3.0 and 3.1, GDI cannot perform output operations directly to a DIB.

Conversion between DIB and DDB is performed by the device driver. Where the driver does not have this facility, the conversion is performed by GDI but only in monochrome. DIBs are slower to use than device dependent bitmaps due to the conversions required.

(1996-09-20)