Select File Menu > Raster > Statistics.

Most raster images contain information about the resolution they were scanned at. When this is the case, resolution values are displayed in the Raster Statistics dialog and Scan2CAD is able to calculate and display the width and height of the image in inches or mm.

When a raster image does not contain resolution information you can type the resolution you scanned the image at into the DPI field.

Resampling

If you change the dpi of an image and the Resample option is not selected, no physical change is made to the raster image. Only the calculated width and height change.

For example, suppose you have an image with the following properties:

If you now change the dpi to 200, the image will have the following properties:

If you change the dpi of an image and the Resample option is selected, Scan2CAD changes the physical size of the image by adding or removing pixels.

For example, suppose you have an image with the following properties:

If you now change the dpi to 200 the image will have the following properties. Scan2CAD has removed some of the pixels.

Warning: We do not recommend that you increase the dpi when the Resample option is selected. Resampling an image so it has a higher resolution is NOT the same as scanning it at a higher resolution. If you resample the image so it has a higher resolution the image will be larger and less wieldy but the detail in it will not be enhanced. In fact you will probably decrease the quality of the raster image for vectorization purposes.