We shade unused cells with shaded background by default since Origin 2019. But the shade showed in printout and exported image or pdf file as well. It should not. Fixed in Origin 2019b.
Workaround before Origin 2019b:
- Choose Window: Properties... menu. Uncheck the Indicate Unused cells with a shaded background checkbox.
- To turn off shaded background for all future workbooks in the future, choose Tools: System Variables... menu. Enter COR as Name and enter 0 as Value. Note: COR is the system variable to control degray of shading. Default is 45. Read more in Improved Handling of Empty Cells in Origin 2019