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I want to accurately reproduce a myopic effect on a picture or a scene.

I will explain... I'm a guy with very high myopia (20° to round). I want to show people how I see without my contact lenses.

I took a picture, and I started playing with blur effects, but none of the effects are close to what I see. My best approach was with a linear blur, with certain inclination, but still very far from my reality.

How can I do this?

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  • \$\begingroup\$ Are Philip Barlow's paintings anything like how myopic people see? \$\endgroup\$
    – Danielillo
    Nov 20, 2022 at 22:50
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    \$\begingroup\$ @Danielillo, for sure these are more realistic than any effect that I've tried and are a very good example Of what I said. If we take a look at the city night pictures, we see the lights that are well-defined shapes. If we use a blur we will never get any shape with a defined contour. From my myopic point of view ;) I never see that perfect contours, but its a good approach, I think this was made striking the camera lens or something like that \$\endgroup\$
    – efirvida
    Nov 20, 2022 at 23:09
  • \$\begingroup\$ Of course, if you've also got a pair of glasses as backup/around the house when you're not wearing your contacts, you can just let them try those on. That's what I do. ;) \$\endgroup\$
    – FreeMan
    Nov 21, 2022 at 13:22
  • \$\begingroup\$ @FreeMan isn't that the opposite effect though? Better would be to give them very strong reading glasses. I'm very lucky with my vision but have a pair of +3.5 reading glasses for occasional very close-up work. With those I can't focus out to arm's length, so a pretty good simulation of myopia \$\endgroup\$
    – Chris H
    Nov 21, 2022 at 16:47
  • \$\begingroup\$ @FreeMan That's not comparable in the slightest, unfortunately. In fact, I can wear my contacts and glasses at the same time, and see perfectly fine (though it's quite tiring). \$\endgroup\$
    – Luaan
    Nov 23, 2022 at 13:20

5 Answers 5

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I don't know how a myopic person sees, but an effect similar to that of the paintings described in the comment can be achieved with Photoshop.

Starting from this image:

enter image description here

  • Duplicate the layer
  • Change the image adjustment to desaturate
  • Apply a filter minimum (around 10px)
  • Gaussian Blur around 5-10%
  • Change the mode to Soft Light
  • Choose the opacity

enter image description here

Hide this layer and go back to the original one

  • Apply a filter maximum (around 15 px)

maximum

To soften the edges you have to modify the channels individually

  • Duplicate the red channel
  • Delete the content of the red channel
  • Load the selection of the duplicate of the red channel (delete this channel)
  • Invert the selection
  • From the selection menu, choose modify, smooth (around 10 px)
  • Activate the empty red channel and fill the selection with black
  • Repeat the operation with the green and blue channels

enter image description here

  • Blur this layer and show the desaturated layer

enter image description here

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  • 14
    \$\begingroup\$ I'm sitting here with my computer glasses on (vision correct to just beyond arms length - the distance I sit from my monitor). I look at your last image, then take the glasses off and look away from the screen. Other than the color band on the black sweatshirt with the grey chevron, that's actually pretty close to what I get (myopia @ -4.5). There's a bit too much color fringing around all the people's legs, too - I don't get the "grey/brown" band around the dark pants legs between the pants & sidewalk, but dang, that's a really good start! \$\endgroup\$
    – FreeMan
    Nov 21, 2022 at 13:15
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    \$\begingroup\$ All in all, just too much remains of the blockiness of your Apply a filter maximum (around 15 px) step. Different px settings may get it closer to what I see. But really, this is getting pretty close. Kudos! \$\endgroup\$
    – FreeMan
    Nov 21, 2022 at 13:18
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    \$\begingroup\$ Note that this is an approximation, all steps can be readjusted. By the way, I'm not myopic, I have no idea how a myopic sees. I only tried to reproduce Barlow's paintings \$\endgroup\$
    – Danielillo
    Nov 21, 2022 at 13:20
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    \$\begingroup\$ You did a pretty good job, I'm impressed (and you've got my +1). I'm trying to add in, for other's benefit, what I do see without glasses/contacts. Now that I look a little more, the background is a little too blocky, too. I've got some VHS tapes on a shelf in the other room (yes, VHS, no, don't ask), so I've got nice rectangles that I've been comparing to - they're notably rectangles w/o the glasses, but the edges are much softer. Again, no criticism, just to get the thoughts flowing for you/others if someone wanted to tweak the approach w/o being myopic. \$\endgroup\$
    – FreeMan
    Nov 21, 2022 at 13:31
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    \$\begingroup\$ For comparison, here is what GMIC lens blur effect produces: i.sstatic.net/TRPh3.png \$\endgroup\$
    – jpa
    Nov 21, 2022 at 14:36
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Myopia means that our eyes can't focus anything further away than a few centimeters. As Tetsujin already said, it's difficult (if not impossible) to reproduce that in post-processing. It should be done when taking the photo.

To reproduce the visual effect, you have to

  • reproduce the short focussing distance, so you'll probably need a macro-capable camera/lens,
  • reproduce the pupil's diameter with the lens aperture.

Manually focus the camera to the proper distance for your myopia:

  • 1 meter divided by the myopia degree in diopters, e.g. 14cm for -7 diopters or 5cm for -20 diopters.

Close the aperture to the proper value:

  • focal length divided by the pupil diameter (can be something between 2mm in bright light, or 8mm in the dark), e.g. for a 50mm lens, to reproduce darkness vision, use 50/8, so set the aperture to f/6.3 (*). For the calculation, be sure to use the real focal length of your lens, not some "35mm equivalent" value.

(*) When focussing at close distances, lens parameters can change a bit, depending on the optical construction. So, the "perfect" reproduction might be achieved somewhere in the range from f/4 to f/8. Of course, feel free to experiment with your lens until you're satisfied with the results.

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I'm not good at the maths on this kind of stuff… but if myopia is light focussing before the retina [which makes it relatively easy to focus on close objects but not those farther away], then wouldn't a fairly accurate recreation be to put an extension tube on a DSLR, set to infinity, or even just to pull focus too close? That will generate the bokeh balls, which post-process blur could never do.
This is literally only being able to focus close-up, though I doubt anything can truly compensate for the way the brain generates a depth map as we switch our eyes to focus at different distances.

Some very quick-sketch examples - me holding out my hand at arm's length, in focus[ish] which is about as close as this lens will actually focus, hence the 'ish', with
a) a picture & some xmas lights at about 6-8ft &
b) against the window, with distant houses.
[Scuse the 'fine art' ;)

enter image description here

enter image description here

You could pull the focus even closer with an extension tube. I tried this, but my shortest tube is too long to show anything useful, it's all a very long way out of focus at any distance over about 6" unless I use a very long lens, 150 - 300mm, which then looks nothing like 'seeing'.

These were done with a 50mm f/1.4 lens on an APS-C crop-frame camera, so it looks more 'zoomed' than natural vision. I tried with a 35mm f/1.8 which would show a field of view closer to how the scene would appear in reality, but it doesn't generate enough blur to really show the effect properly.

You can get a very similar effect with a recent generation smart phone using the 'portrait' mode, which will artificially generate exaggerated out of focus backgrounds.

To try recreate this from an existing sharp image, you would need to mask out the hand, then apply blur only to the background. To achieve such an extreme difference with good subject separation you would probably be better off compositing the picture from separate foreground & background images.

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  • \$\begingroup\$ Making a real camera myopic certainly seems like a good solution. With my (cheap) extension tubes I used to most often use just the pair of adaptors (Canon-threaded and threaded-Canon), no actual threaded tube. Those cheap ones force a wide open aperture which helps here \$\endgroup\$
    – Chris H
    Nov 21, 2022 at 11:23
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    \$\begingroup\$ @ChrisH - mine connect correctly on the electronics side, so all I really lose is autofocus, which tries & fails most of the time, so it's a manual focus effort. My skinniest tube segment is 12mm [then 20 & 36], which is just too much to do this effect subtly, no matter what aperture I set. \$\endgroup\$
    – Tetsujin
    Nov 21, 2022 at 11:28
  • \$\begingroup\$ I just remembered mine are right here in my desk; now that I have a macro lens at home they're relegated to the 350D I keep in work. They only go a little shorter than yours (or went - the shortest actual tube is stuck). AF seems marginal if you mess about with the optical path (teleconverters are worse still), and not great near the close-focus limit, so I tend to use MF anyway (or fix the focus and use a focus rack) \$\endgroup\$
    – Chris H
    Nov 21, 2022 at 11:36
  • \$\begingroup\$ ... another hardware solution is an old manual lens on an adaptor, which inherently adds a bit of thickness. I can fit C-mount lenses to my Canons which would work well here (barring vignetting of course), but M42 would be better \$\endgroup\$
    – Chris H
    Nov 21, 2022 at 11:37
  • \$\begingroup\$ The only thing this is missing for my vision is the duplication of things in the background that happens when I'm focused on my hand about 6 inches in front of my face (the farthest distance I can accurately focus on my hand). That whole "binocular vision" thing of two eyes vs "monocular vision" thing of a single camera lens. That and the focus on the hand is a little softer than what I can actually achieve. \$\endgroup\$
    – FreeMan
    Nov 21, 2022 at 13:21
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An initial note.

You are mentioning "linear blur" which makes me think that additionally to myopia you have astigmatism, and that is a different situation than the one described in your question.


So, for myopia. Basically is that you can not focus on distant objects, so you are only focusing up close.

As you are asking on a photography forum, so first let me answer from a photography perspective.

A. Simply add a magnifying glass in front of your camera. I added a simple lens (Attached to tweezers) As your myopia is pretty strong I would say that your focusing distance is just some cm, so this case is perfect. You can see my finger. (Do not forge my fingerprint)

That is an accurate representation of focusing very close to the eye with some distant objects.

B. I also took a lame picture without the glass, so let's use a digital filter on postproduction.

"I started playing with blur effects"

As you are not mentioning any software, let us use Gimp which is free.

Go to the menu Filters > Blur > Lens Blur and play with the values on Radius and Highlight factor (C)

Of course, this has limitations, and the limitations come also because of the limitations of the dynamic range of the cheap cellphone camera I used, but this filter, (compared to a normal gaussian blur) simulates a bit the rounded shapes of a bokeh. (D)

enter image description here

For a more accurate representation of the light itself, I needed to tweak the values, affecting all the image and making it look "faker". You would need to mask and apply the filter in different amounts.


As I said, this is only addressing myopia. But what you see with your eyes can be affected by astigmatism, and probably some other things, like diffraction caused by your eyelashes, or stuff floating in your intraocular fluid.

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As far as I know this is a focus blur, but the amount of blur varies with the distance of the object, so applying a blur to a flat image doesn't work. There are focus blur filters for pictures editors that work together with a "depth map" that tells them at what distance are objects in the picture and let them apply the proper amount of blur in each area.

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  • \$\begingroup\$ Even with a depth map, there's a lot of lost information in the correctly focused image. All you can do is make stuff vaguely blurry, which is very far from actual myopia (though of course it's usually how myopia is shown in movies, for obvious reasons). \$\endgroup\$
    – Luaan
    Nov 23, 2022 at 13:25

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