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Comment by proudfoot | Hacker News Reader

You're not capturing the rays, you only get where they strike. You can't fix it all computationally.

Secondly, we already do correct distortion and chromatic aberration in software, but this doesn't really make up for loss of resolution that you can't fix. Information is being lost.

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That's the point though: the quantization absolutely introduces errors, but there were there to begin with. You're comparing the computed result of my "cheap camera" not with its competitor's sensor output but with the hypothetical focal plane of the competitor's lens. And that's wrong, because the competitor has pixels too.

The error you get out is of the order of the sampling error you put in. That's true of all lenses.

I'm saying with the same sensor, the competition will have better data compared to you, since the rays are striking where they should be.

Information is lost when a ray strikes somewhere it shouldn't. Things get blurred and cannot be recovered. You can't fix this with software.

> You can't fix it all computationally.

Can't you? If you're dealing with known hardware, then you can apply a deconvolution. Blurring can literally be undone, people do it all the time. It's harder when you have to estimate the kernel, but much easier when you already know the lens's exact properties. Also when you apply it directly to RAW data.

So not exactly sure which information you're referring to you when say information is being lost?

Sure artifacts can be introduced from noise, etc., but that's all just tradeoffs. If a simpler lens is letting in more light, or you put money towards the sensor rather than the lens, the end result may well be better, no?

Some blurring is like pixelization

You don't have the exact kernel, if you're even slightly wrong you can end off being worse off. You'll have very significant variation in lower quality optics.

And there's a variety of sharpening tools that claim to do this! DxO is a company that sells a raw processor for precisely this purpose. People still buy better lenses.

I think you might be able to do a good job if you had a depth map of the image. You could use ML to guess them. Computation without that treats incident angles that vary by the distance ratios as the same.

If you have depth information blurring can be undone theoretically, but you don't.

Isn't the location that a ray strikes entirely a function of angle of incidence, its frequency, and the particular lens? Why couldn't that function be determined and inverted?

Optimally yes. But in practice multiple rays from multiple angles strike the same sensor.

Lens design is about minimizing this.

The phase matters as well if some parts are captured out of the focal plane.

Even if reconstruction is possible, it might amplify the noise by a substantial amount.

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