How to calibrate your Desktop Screen for colour accuracy:-
Here is a YouTube video to help those of you who don't have a fancy £180 calibrator tool to get your screen calibrated accurately so your prints and DPI's are colour accurate. This works for Desktop PCs. However, for Laptops it's a little more complex unless you skip the 'Brightness and Contrast' section – ideally, don’t skip it.
The attached chart can be used to gauge how well your screen is calibrated. Ideally look at it while there is no other lighting in the room. Don’t assume that charts downloaded from the internet are accurate. This one wasn’t. I’ve edited it and labelled it so it is accurate (Tip - don’t mess with it):-
The Red square’s RGB really is R= 255; G=0; B=0
Green is R=0; G=255; B=0
Blue is R=0; G=0; B=255
Yellow is R=255; G=255; B=0
Black is R=0; G=0; B=0
White is R=255; G=255; B=255
Ideally your brightness and contrast should be adjusted so that you can see as many of the black/grey (2-24) and whit/grey (243-254) squares as possible but be realistic. Most screens won’t be able to distinguish all of these and if the detail of the shadows in your photo can’t quite distinguish between (R=2; G=2; B=2) & (R=4; G=4; B=4) the chances are nobody else would anyway.