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Comment by ahupp | Hacker News Reader

If you can only subtract light the contrast of what you're viewing against the background will always be poor, almost by definition. Also doesn't handle color.

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Why could it not handle color if it had R/G/B subpixels and adapted the intensity of each pixel based on the color of the light passing through that area of the screen?

The intensity of light is quite high outside, could an LCD not darken it enough to have sufficient contrast if you were OK with it only working outside?

Just do a quick search for transparent LCDs, I think it will answer your question. (Not enough light gets through, the result looks more like high resolution stained glass than a Retina display)

How could you determine the color of the light passing though that area of the screen?

LCD can’t darken, aren’t that transparent in the first place, also can’t focus without microlenses and you won’t be able to look through microlenses. If you still think it viable you can prototype the optics you described using old Nokia phone LCDs or some later GameBoy models that has easily removable backlights.

Are you being specific about the word darken? Because LCDs are design to either allow or block light. So technically an LCD can "darken" incoming light. But I think the point of inconsistent lighting from the environment would be the biggest challenge.

The best example of transparent display I've seen in production is:https://glas.johnsoncontrols.com/

But the material on that seems darker and I believe they use an edge light to provide higher contrast.

I think the distance from the eye, as well, would be difficult if you aren't doing some type of projection, like what is used in the the article.

Darken as in response to “can’t LCD darken enough” in parent.

Anyways any LCD can be a transparent LCD if you peel off backlight layers if you want to experiment with. Search for “DIY transparent LCD” or “LCD side panel casemod”

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