yes, reading from a file is a wonderful idea! In fact, that's how objects like 3d models and textures are generally read into memory.

I would use a plain text or compressed text file to read from, not a texture file (unless you want to read in a texture) since texture file will generally have a specific storage format which you might not need. For example if you don't want the trouble of parsing the red, green, blue from a .bmp file then it would just be easier to read from text. Also some formats may be compressed like .tga or .dds so you should be careful with texture/image files when loading.