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?
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:
Hide this layer and go back to the original one
To soften the edges you have to modify the channels individually
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!
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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
Manually focus the camera to the proper distance for your myopia:
Close the aperture to the proper 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.
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' ;)
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.
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)
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.
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.
