Because Windows Help is device independent, it stores text and graphics by point size rather than by their width and height in pixels. When displaying bitmaps, Windows Help tries to maintain a bitmap’s logical size across all displays (EGA, VGA, or 8514, for example). To do that, Help determines whether a bitmap includes information about its resolution. If it does, Windows Help either displays the bitmap as authored or modifies it (by stretching or shrinking it) if the display resolution is different from the authored resolution. If no resolution is stored with the bitmap, Windows Help uses the default values for VGA.
Because of stretching or “guessing,” Help bitmaps sometimes do not appear the same as they were authored—unless the authoring monitor and the display monitor have the same resolution. For example, a bitmap created on a VGA display becomes distorted when displayed on an 8514 display. That is because Help uses the logical size (pixels per inch) of the display driver to determine how to size the picture. VGA displays have 96 pixels per inch, and 8514 displays have 120 pixels per inch. In both cases, Help keeps pictures and text proportionate. So, if you create all your bitmaps in VGA resolution, Help will stretch the bitmaps when displaying them on an 8514 monitor.
Note:
Help considers an 8514 display to be any monitor that has 120 pixels per inch. Because some high-resolution monitors deliver 96 pixels per inch to get more inches on the screen, Help uses the VGA bitmap on these devices.