When you save a part or assembly in .tif, .jpg, or .psd format, you can save the image to a custom size by specifying dots per inch (DPI) or paper size.
In the Save As dialog box, select the file format from the Save as type list. In the Export Options dialog box, click Options to specify the print capture size.
For more information, see SolidWorks Help: TIFF, Photoshop, and JPEG Export Options.