A file with .igs (Initial Graphics Exchange) extension is a 2D-3D design exchange file format that is independent of source or destination file format specifications used by CAD applications. It is used to exchange design information about circuit diagrams, wireframes, the freeform surfaces between two independent systems. IGS files can be opened by applications such as Autodesk, FreeCAD, CADEX CAD Exchanger, and other similar applications.
TIF or TIFF, Tagged Image File Format, represents raster images that are meant for usage on a variety of devices that comply with this file format standard. It is capable of describing bilevel, grayscale, palette-color and full-color image data in several color spaces. It supports lossy as well as lossless compression schemes to choose between space and time for applications using the format.
You can also convert IGS into many other file formats. Please see the complete list below.