A plethora of health issues may occur when human eyes are exposed to blue light for an extended period of time. For example, long absorption of blue light around the wavelength of 482 nm at night by the light sensitive cells called “intrinsically photosensitive retinal ganglion cells” (ipRGCs) on human retina can cause harmful changes to the human circadian clock. The harmful effects may include insomnia and low sleep quality. Blue light at the high energy wavelengths (380-420 nm) can cause other types of health issues as well. Although simply applying a blue light blocker to a display device can reduce the harmful blue light, the blue light blocker adversely generates unpleasant yellowish and/or pinkish effects on the display. The degradation of image quality is undesirable for commercial products such as, for example, TVs, smartphones, and computers.