# Print something to be seen in focus by person w/o glasses?

Is it possible to print something with an ordinary laser printer that is blurred in such a way that it can be seen clearly by someone who ordinarily requires a strong prescription to correct their eyesight but would appear a blurred mess to someone with normal eyesight?

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"someone who ordinarily requires a strong prescription to correct their eyesight" would see regular print as a blur and blurred print as REALLY blurred

sophiecentaur
Is it possible to print something with an ordinary laser printer that is blurred in such a way that it can be seen clearly by someone who ordinarily requires a strong prescription to correct their eyesight but would appear a blurred mess to someone with normal eyesight?
Consider the limiting case of blurring where you have a uniformly grey page, instead of black text on white paper. Is there a way a lens can make text out of it?

phinds
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Is it possible to print something with an ordinary laser printer that is blurred in such a way that it can be seen clearly by someone who ordinarily requires a strong prescription to correct their eyesight but would appear a blurred mess to someone with normal eyesight?
No.

I used to work in photo printing - back in the days of chemicals and negatives and stone axes.
A lady came in and handed me a print of a blurred subject (it was blurred in the negative). She wanted me re-print it and "correct the blurriness". (After all, my machine can make pictures blurry; why can't I just reverse the process?) No can do. The information from the scene is gone; it's not there to be extracted.

On the flip-side, consider what would happen if we could do that. If we could turn any blurry image into a sharp one, then cameras would not need to focus at all. We could just take blurry pictures with our lensless cameras and simply extract all the original data from them into a sharp picture!

Try an experiment to convince yourself. Draw a diagram with a few key points in it, and draw a simplified eye with focusing "lens" and image plane. See if you can draw some out-of-focus points that somehow cohere just right so that they make sharp-edged points on the image plane.

Keep in mind that you can't select which parts of the image plane only receive certain rays from certain parts of the object.

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davenn and anorlunda
She wanted me re-print it and "correct the blurriness". (After all, my machine can make pictures blurry; why can't I just reverse the process?) No can do. The information from the scene is gone; it's not there to be extracted.

Unless you have these CSI machines:

Merlin3189 and DaveC426913
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A lady came in and handed me a print of a blurred subject (it was blurred in the negative). She wanted me re-print it and "correct the blurriness". (After all, my machine can make pictures blurry; why can't I just reverse the process?) No can do. The information from the scene is gone; it's not there to be extracted.
Times have changed.
Using current image processing software I have "refocused" an out-of-focus circuit diagram from one of the threads here that I then re-posted, and have (largely) removed motion blur from digital photos, specifically of a moving vehicle taken at night that was too far away to use a flash. It does take a lot of time and patience though, not commercially viable as a consumer service... especially considering that as of a few years ago, the wholesale price for photo touch-up started at \$100/hr.

The original image 'as taken.'

Motion blur was removed for the trucks. As a side effect, the rest of the image is degraded.

Cheers,
Tom

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davenn
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Not a totally valid objection here, I think. If someone wants to discusses putting a screw in a wall with a hammer, it is quite in order to suggest a screwdriver. But @phinds is quite right that the OP's request for an actual image, printed on paper, is hardly possible. Some fancy glasses, at least, would be required.
The equivalent process to what a computer can do is probably achievable with an appropriate 'lens' if the aberration is not too great .
The action of a lens involves a Fourier Transform of an image at the focal plane and phase shifting parts of the spectrum can bring the phases of those parts together again. See this link which describes the basics of Fourier Optics. High and low pass (spatial frequency) filters are described and the detail of a blurred picture can be extracted optically (thereby ruining the picture as something to look at).
The sort of enhancements that Photoshop (others are available) can do are way beyond what optics can achieve.

"someone who ordinarily requires a strong prescription to correct their eyesight" would see regular print as a blur and blurred print as REALLY blurred

It's hard for me to tell whether I'm not understanding the answers or if my question is not being understood how I intended it. Would it make more sense if I asked could an image be printed with "anti-blur", blurred in such a way that I could read it clearly with my glasses off but most other people (and myself with my glasses on) would not be able to read it? Like, if I know what my prescription is, is it possible to calculate how the image will be deformed by the lens in my eye and apply counter-deformations to counteract those? Then I could print text out and I'd be able to read it relatively easily but most others would not. Sorry if everyone did already understand my question and it just isn't possible.

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It's hard for me to tell whether I'm not understanding the answers or if my question is not being understood how I intended it.

No, I think your responders understood

Would it make more sense if I asked could an image be printed with "anti-blur",

anti-blur ?? never heard of it ... do you have a good reference ?

blurred in such a way that I could read it clearly with my glasses off but most other people (and myself with my glasses on) would not be able to read it? Like, if I know what my prescription is, is it possible to calculate how the image will be deformed by the lens in my eye and apply counter-deformations to counteract those? Then I could print text out and I'd be able to read it relatively easily but most others would not. Sorry if everyone did already understand my question and it just isn't possible.

No, I know of no lens or set of lenses that can turn a blurry image into a sharp or near sharp image
It's still going to be blurry with or without glasses

anti-blur ?? never heard of it ... do you have a good reference ?

I phrased it this way to make it easier to understand what I'm asking for. I want the antithesis of what my own defective eye lenses do to images I look at.

No, I know of no lens or set of lenses that can turn a blurry image into a sharp or near sharp image
It's still going to be blurry with or without glasses

My glasses make the blurry image I see without my glasses appear sharp. Is it possible that I'm using the wrong terminology? Perhaps "blur" has some specific definition in physics which does not apply to the case I am attempting to describe.

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My glasses make the blurry image I see without my glasses appear sharp.

then your glasses are the incorrect prescription for you ... either
2) if they used to be OK then your eyes have changed over time and you need retested and a new prescription
... I go through that ( as most glasses wearers do) every year

welcome to the reality of wearing glasses

Dave

then your glasses are the incorrect prescription for you ... either
2) if they used to be OK then your eyes have changed over time and you need retested and a new prescription
... I go through that ( as most glasses wearers do) every year

welcome to the reality of wearing glasses

Dave

Negative. Without my glasses, my vision is blurry. With my glasses, my vision is not blurry. This use of the word blurry is layman and may not be correct usage in the field of physics. My glasses make a blurry image sharp.

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My glasses make the blurry image I see without my glasses appear sharp.

I guess if it isn't #2 reason I stated above ... then WHY are you wearing glasses if you don't need them to get a sharp image ?

As I aged through my 40's and into my late 50's it was my near vision focussing that started failing first ... I couldn't focus on anything within a metre or less.
As the years went by, my longer vision focussing slowly got worse till I finally needed glasses to be able to walk around and drive safely

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Negative. Without my glasses, my vision is blurry. With my glasses, my vision is not blurry. This use of the word blurry is layman and may not be correct usage in the field of physics. My glasses make a blurry image sharp.

so, that is what glasses are supposed to do ... it is your eyes and their poor focussing that is making things blurry
correcting lenses solve that problem ... so what is the problem ?

It ISNT the image that is blurry ... It's your view of it without correcting lenses that make it appear blurry to you

so, that is what glasses are supposed to do ... it is your eyes and their poor focussing that is making things blurry
correcting lenses solve that problem ... so what is the problem ?

It ISNT the image that is blurry ... It's your view of it without correcting lenses

You said:

No, I know of no lens or set of lenses that can turn a blurry image into a sharp or near sharp image
It's still going to be blurry with or without glasses

but my glasses turn a blurry image into a sharp image for everything I look at (in concert with my own internal eye lenses). Thus I reason that there must be a way to calculate how an image should be displayed to a person with deformed eye lenses.

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but my glasses turn a blurry image into a sharp image for everything I look at.

you are not reading what I am saying !

It is ONLY BLURRY to you and anyone else with eyesight focussing problems
If the image is sharp to good eyesight viewers and blurry to you, then it is YOUR eyes that have the problem
That is what your glasses are designed to do, restore the original sharpness of the image
as seen by everyone else with normal eyesight

phinds
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It's hard for me to tell whether I'm not understanding the answers or if my question is not being understood how I intended it. Would it make more sense if I asked could an image be printed with "anti-blur", blurred in such a way that I could read it clearly with my glasses off but most other people (and myself with my glasses on) would not be able to read it? Like, if I know what my prescription is, is it possible to calculate how the image will be deformed by the lens in my eye and apply counter-deformations to counteract those? Then I could print text out and I'd be able to read it relatively easily but most others would not. Sorry if everyone did already understand my question and it just isn't possible.
I can only suggest you reread post #2. I see no ambiguity.

davenn
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Thus I reason that there must be a way to calculate how an image should be displayed to a person with deformed eye lenses.

there is ...

correcting for near sightedness ... when far things are out of focus
https://www.physicsclassroom.com/class/refrn/Lesson-6/Nearsightedness-and-its-Correction

correcting for far sightedness ... when nearthings are out of focus
https://www.physicsclassroom.com/class/refrn/Lesson-6/Farsightedness-and-its-Correction

Note closely why the 2 conditions occur because of where the eye lens focal point is

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Okay, thanks everyone.

Nik_2213
Back to OP's request...

IMHO, there is one situation where you could go some way towards this. In case of severe astigmatism, you may be able to smear the image sideways such that uncorrected eyes partially suppress said smear. But, it would remain visible to 20/20 vision, just take a bit longer to make out...

FWIW, if you need a free, high clarity font for personal / non-commercial use, search for APHONT, c/o American Printing House, the US equivalent of UK's RNIB...