Colours uses in DC comics by Geoff Johns

The colour in comics, sometimes actually gives even more meaning than just black and white. It is there to represent items and even tinted colour would explain things. 

Flashpoint

The tinted colour used throughout the pages and panels of yellow is to establish and exhibits the point of view from the Flash's point of view who is narrating his within the first two pages. the third page is shown to show from a parallel earth from where The Flash is from. It is seen mainly from the third point of view with flash and Billy Batson in the panel to remind the audience of whom memory that they are looking at.

The tinted colour of blue that is used throughout these four pages (or one really big one if reading an ebook version of it) is to introduce the characters in Flashpoint as the audience has not met this version of the characters as this story is set in a timeline where the Flash changed its character.

The colour of the background is shown to signal to the audience that there is something important or critical happening or even the action scene. The black borders would make the panels to pop out much more so the audience would focus on the panels even more and less than the speech bubbles, compared to white where there is more explanation or less important events or a resolution have shown. This would make the audience more relaxed and look at the worded pannels even more. 

Blackest Nights

The green border colour is used is showing the past of the events that happen. These events remind longtime readers of the past events which would lead to a bigger story which is in the story.

 The black tinted colour is used to show the death and darkness of the graphic novel/comic story arc. The black tells the audience that there is something wrong and that there is not much help on if there is victory or anything good to come.

The white is strongly emphasized by the end of the story in which it is showing that it is near the end, and that victory is coming. The colour white represents, peace calm and happiness as it is pure and that the heroes end the villain. with the myst in the final few pages are used to show the comeback of some of the dead characters. This creates the revelation that new revival of characters and for the new peace which is shown.