The standard margins, expressed in millimeters, could result in the
usable page space being much smaller than 1000px used for the DC size
when using higher DPIs, which means that the test checking that a 2400px
image took only 3 pages could fail, as it could require 4 of them in
this case.
Fix this by getting rid of the margins, as this should ensure that the
page height is exactly 1000px now, independently of the actual DPI.
