When is a square not a square?

Software darktable
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I was all set to ask a general question about aspect ratio display but the issue appears to be with my eyes/brain.

Over several months I have been thinking that images in darktable looked taller than they did wide. An untouched portrait would look “taller” than an untouched landscape would look “wide”, if that makes sense. So I cropped an image using the square aspect ratio and exported it. I was wondering if the image would be square in an image viewer. I got my steel rule out and measured the “square” RAW image in darktable and the exported jpeg in Chrome.

I was slightly surprised to see that height=width to within my measuring precision in both cases.

Many years ago, when TVs were almost square I was told that if I watched too much I would get square eyes. I now have a 16:9 monitor so I guess I have rectangular eyes.

Edit: Thanks for all your comments. I have confirmed that it is my eyes/brain and the illusion appears to be most extreme when the landscape image fills the available screen to all edges, turning it through 90 deg then looks like a different aspect ratio but it quite definitely isn’t.

Attached is a 2048x2048 square image. (If I can find how to attach it.)

R7_C9910_03_02
R7_C9910_03_022048×2048 409 KB

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Do you wear varifocal glasses ? They may be the cause of this perception.

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Looks square to me. Maybe you have somehow set your pictures to display fullscreen stretched.

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For me this looks a square… I don’t see the same effect you are talking about

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I wear a pair of “arm’s length” reading glasses for editing, not varifocal. I have a slightly stronger pair for reading. I have just tried a bit of with and without glasses and the slight impression of tallness is still there.

Now I have played about a bit I see that it is most noticeable with a rectangular image if the screen is set to “fit”. If I zoom out so that neither orientation fills the height then it is not noticeable. It is not much at its worst anyway which is why I haven’t bothered to investigate before.

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Very nice image by the way!

I suspect that showing a square (the picture) within a rectangle (both the screen and the application) leads the brain to this interpretation.

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This might be a “feature” of your eyeballs. The retina is roughly the inside of a sphere. The brain unscrambles this spherical projection so that, for example, straight lines appear straight. But human bodies are not fixed over time: the geometry of bone and muscles change, inducing change to the eyeball’s shape.

A couple of years ago, I noticed that when looking at straight lines such as the edge of my laptop screen with my right eye, there appeared to be a slight bump in the image. My optometrist explained this to me, and said it was nothing to worry about, but offered a test to investigate further. I declined the test.

A year later, there were no longer any bumps.

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I have a similar feeling. For me, 3:2 looks balanced, but for some reason 2:3 doesn’t look that balanced to me, it almost looks stretched or too tall. This may be a function of seeing the image on a screen of course, as there is much more real estate for one than the other(unless you rotate your screen). I should do some prints to see if this effect translates to real life.

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Lots of screens may be rotated 90 degrees for testing this out… Of course rotating the square picture accordingly. And see…

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For what it’s worth, I printed some square crops and they are, indeed, square.

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How jolly unexpected :innocent:

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Thanks and thanks @Jetze for the compliment on the image. I have now measured a 3:2 original in landscape, rotated it 90 deg then measured again. One way = 1.496 the other 1.5, which is close enough for me. I was surprised at how hot the bottom edge of the screen was though, so I have now moved the Raspberry Pi & screen from under it for better air circulation.

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Thanks @Marfie what I meant is a bit different and I should have expressed myself more clearly.

I meant that a square picture shown on a landscape monitor might seem to be higher than wide. Shown on a portrait monitor it might bee the opposite.

All under the assumption we deal her with an optical ‘delusion’. :slight_smile:

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As many have alluded to here, context matters. Psychologically and physiologically, we interpret the world based on our surroundings. One easy example is viewing an image using different software. Already the shape of the photo is very different from one app to the next. It happens with zoom level and location on the screen as well. At work, when I email using Outlook, I tend to shrink the image to mitigate some of its strangeness.