looking for a reading app that controls the blue spectrum

[Friendly]

the coming LG G Pad II 10.1 will be coming with a specialized app that will control the blue spectrum in the backlighting to make it easier on the eyes when reading.

I have found reading on the iPad to be straining on the eyes. does anyone know if there's any app out there that allows for this kind of control?

I love using my Kindle Voyage, but I can't use it for PDF's and I read a lot of PDF's with images that must be used for reference.

thanks!