I want to create a collage and print in 60cm*40*cm picture on an aluminum frame. I am trying to use grid collage – big photo. It is not clear to me how I can get a 300dpi (printing quality) picture out of the collage. Currently, the file is saved as 96 dpi with 2880W*2400H. But when I try to upload the picture. The printer software shows that a quarter of the image won’t be printed. So I am puzzled. Kindly let me know how to proceed?