Size requirements for contest
I am entering a photo contest that has the following format requirements: "Format: Images must be in RGB color format, horizontal, 300 dots per inch, 8 bit, and at least 9x12 inches when printed at 300 dpi. The pixel width should be 3600 and pixel height should be 2700." I have no issue setting this in Photoshop, however, the submission page requires maximum of 5mg size. How can I reduce the MB size without reducing the format required. I have tried saving as jpeg, gif and png and using Windows 11.

