The image generated on the computer does not have the original, which could distort the format, etc., as this is the original image. In whatever format you have not recorded a render, it will be such what you it has generated, with the exception of compression formats and distorting its data on the pixels, for example, * .jpg. And since there is no difference, I personally render in * .png , but if you save the picture in the bmp, tif or jpg without compression, you save the information about the colors of pixels such as it was generated by 3ds Max. The only thing on that, on what you should pay attention to is the actual number of pixels, that is the resolution of the render. Certainly for the board it must be great, a few thousand to several thousand pixels. But you have already learned in the printer that will print the board.
Incidentally correctly billboards from the word billboard (bulletin board or billboard )😉