The units for height and widths are calculated as follows.
Some bitmap formats always have a dpi setting some formats do not have a dpi setting embedded in the file. Windward checks to see if there is a DPI setting and tries to use that. We convert the DPI and multiply by the number of pixels to calculate how much space it consumes on the page.
Here is some information on the most common formats.
GIFS – never embed DPI information in the file.
JPEG – always embeds the DPI information in the file, but it is not required and you can find JPEG files that have not DPI information embedded.
PNG – embeds the DPI information in the file 99% of the time but it cannot always be counted on, similar to the way JPEG operates.
If there is not DPI value associated with the file Windward assumes 96 DPI.
If you set a height and width then the image file defaults are overridden with those dimensions. The height and width is in twips which is 1/20 of a point, 72 points in an inch = 1440 twips in 1 inch.
Starting with version 9 you can set the width properties to: bitmap, specified, specified-width, and fill-width. In the case of the last two the aspect ratio is preserved - but in both cases you set the width and the height is automatically determined.