Make one more duplicate of the lines and the background square and change the fill for the background square to the two RGB values shown here.

Change the fill for the lines to the two RGB values shown here remembering to apply the lighter fill to the upper set of lines.

Save your work and take a short eye break.

One-by-one, select each square with its light and dark lines and convert the selection to bitmap (Arrange > Create Bitmap Copy... or right click on the selection and select Create Bitmap Copy... from the pop up menu).

Change the Color Depth: to True Color. In the Bitmap Size tabbed section, change the DPI: setting to 200.

You should now have four separate bitmaps.