Why do images appear darker on some displays?
The answer lies in the gamma.
Gamma is one of the most difficult computer terms to define. Even experienced computer technicians have a difficult time understanding what it is. We will attempt to simplify it.
Gamma affects how a computer generates images. Images which are not properly corrected can look either bleached out, or too dark. Trying to reproduce colors accurately also requires some knowledge of gamma. Varying the amount of gamma correction changes not only the brightness, but also the ratios of red to green to blue. When expressing a color in RGB (red, green, blue), what we are specifying is the amount of light which will be emitted from each phosphor, as a fraction of full power. What we are actually specifying is however the voltage which will be applied to each electron gun.
Gamma is a measurement, like inches or calories. Gamma can also be described as the measurement of contrast that affects the midtones of an image
A gamma measurement can apply to several elements within your computer system It reflects a relationship between input and output. Gamma is a mathematical formula which describes the relationship between the voltage input and the brightness of the image on your monitor screen.
And so. when it comes to graphic design this is why some images may look different depending on what display you are looking at it on.