What’s spectral power distribution (SDP) graph and why do we find necessary to include it in our reviews


Our display tests included in the reviews aim to give a more detailed insight of what the user gets when buying a laptop. It’s essential for buyers searching for better image quality suitable for multimedia, gaming or even professional photo, video editing or general design work. However, essential properties for the quality of the image aren’t the order of the day for some and sometimes the health impact is strongly overlooked in some cases so that’s why we included the so-called PWM testing. The pulse-width modulation, which most laptops use for adjusting screen brightness, is essential for users with sensitive eyes, especially when using the device for longer periods.

Aside from PWM, though, there’s the thing called blue light emissions. Several studies show a correlation between damaged macula in one’s eyes and the emitted blue light from modern screens and you can read more about the issue in our dedicated article. So the simple solution of keeping your vision intact is to steer away from flickering screens and reduce the amount of blue light emitted from your screen. And we are here to help you.

Introducing the so-called SDP graph or “spectral power distribution”, which gives you enough information of the visual profile of the color characteristics of a light source, hence the screen. Or in other words, the SDP graph is the true “fingerprint” of how the screen is able to render colors. It also shows the radiant power emitted by the source at each wavelength in the visible region between 360 and 760 nm.

On the image below, you can see the SDP graph representing Lenovo Y700’s screen – a laptop which we are currently testing and the full review is on the way. The left side of the image holds a graph showing the blue light levels with stock settings and on the right, blue levels come down in favor of the warm colors like red thanks to our Health-Guard profile – you can find out more about it in this article.

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Stay tuned for the inclusion of more tests regarding ergonomics and usability of the input devices on a laptop.

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