You should always have your computer monitor really clean. Google something like “how to clean my macbook display” (assuming you have a Mac).
Checking colour when you have a real Gratagmacbeth ColorChecker
Download this Gratagmacbeth ColorChecker JPG file (Colour profile is Pro-photo RGB).
Open this JPG in Photoshop and check it against my physical ColorChecker. Adjust your screen brightness to improve the colour match. Look carefully.
Generally, modern un-cheap computer monitors are pretty good, but certainly not very good, at rendering colour.
Professionals use a hardware colour-checking device to calibrate the colour profile of their screen.
Typical office printers do a rather bad job of rendering colour. Professional printers can be colour calibrated.
Colour, and colour profiles, and colour gamut (the range of colours available on a particular medium and device) is a big subject.
And, how does this website rendering (below) compare to the physical colour checker?
And consider the Kodac Grey Scale guide. Can you, for example, see the difference between 18 and 19 below?
