All large format printing should be done in CMKY mode; RGB is prohibited. Modern printers are typically four-color, but some have six colors, including lighter shades of C and M, which make color transitions smoother and more realistic. When creating designs, adhere to printing standards, as the printing company will adjust the colors to match the proofs.

In both large format printing and photo images, it is strictly prohibited to use a single black value. You must add C, M, and Y colors to create a mixed black. If it's a solid black, it can be set as: C=50, M=50, Y=50, K=100. Especially when using it in Photoshop, be sure to change the black areas to four-color black; otherwise, horizontal lines may appear in the black areas, affecting the overall effect.