Metafile (MS Draw) and Bitmap (Paintbrush) Pictures

• Microsoft Windows operating system versions 3.1, 3.11

SUMMARY

Two basic types of pictures are supported by applications for Microsoft Windows. One is the Windows metafile (*.WMF), and the other is the bitmap (*.BMP and others). The basic difference between these types lies in how they represent the picture.

A bitmap is an expanse of dots, called pixels or pels. Every pixel is the same size, but may be one of a series of colors. Shapes drawn in a bitmap may be limited by this pixel format. For example, a solid circle drawn in a bitmap is really just a rough approximation of a circle, with pixels inside the circle being set to a different color than those pixels outside the circle. The bitmap can be stretched or shrunk, but doing so usually creates undesirable effects, such as rough edges and odd patterns in the picture.

Bitmaps are useful for very detailed images, such as computer screens and digitized photographs. This format is often called a "raster" graphic. Bitmaps can be created with bitmap editors, such as Paintbrush (included in Microsoft Windows versions 3.0 and 3.1). Bitmaps usually have the MS-DOS file extension of .BMP, but third parties have other formats for their bitmaps, notably Z-Soft Corporation's .PCX format. Generally, Windows works best with the Windows bitmap format (.BMP).

A metafile, unlike a bitmap, is a series of shapes and colors that are drawn in a prescribed order on the screen or printer. A circle in a metafile, for example, will remain a circle and can be stretched without showing the rough patterns seen in bitmaps. The drawing process for metafiles is similar to a recording of the image's original creation, where each shape is quickly drawn in the same order in which it was originally created. This is often called a "vector" graphic. Metafiles can be created with metafile editors, such as MS Draw (included with Microsoft Word for Windows version 2.0). Metafiles usually have the MS-DOS file extension of .WMF.

The OLE feature can embed or link either bitmap or metafile images. When a metafile image is embedded or linked, the server application (the application associated with the object) for such objects will be a metafile editor such as MS Draw. Bitmaps that are embedded or linked use the Paintbrush picture to represent the server application.