2CD: (DoubleCAD Native Files): You can use any 2cd file from v1 through v2.
TCW: (TurboCAD Native Files): You can use any TCW file from v4 through v16.
DWG: (AutoCAD Native Files): You can use any DWG file from version R13 to version 2009.
BMP: You can use any standard Windows BMP file. However both BMP files must be the same size. If the images are of different sizes you will get an error message. This limitation applies only to raster images. 
PNG: You can use any standard Windows PNG file. However both PNG files must be the same size. If the images are of different sizes you will get an error message. This limitation applies only to raster images.
JPG: You can use any standard Windows JPG file. However both JPG files must be the same size. If the images are of different sizes you will get an error message. This limitation applies only to raster images.