jpeg images being automatically adjusted in preview

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Level 1

4 points

jpeg images being automatically adjusted in preview

I've seen some similar issues floating around but no definitive answers so wanted to ask here - when viewing jpeg images in preview, darker images often get automatically adjusted after I open them - e.g. at first the image looks exactly as I captured it (and exactly as in the small thumbnail) but after a few seconds or zooming in / out, suddenly the image is lighter, usually greyer/greener and a lot less contrasty. I've tried to turn off any automatic settings but can't find any that are turned on or adjustable?

When I drag aforementioned automatically-adjusted jpegs into photoshop, it is the greyed/lighter image that appears, not my original. Obviously this affects photographers a lot so i'm wondering what's happening here? I don't think i'ts a GPU processing image issue (e.g. as noted https://apple.stackexchange.com/questions/326646/why-does-the-contrast-change-when-you-zoom-out-of-an-image-on-preview-on-mac?fbclid=IwAR12HOgrE004mWUywmVRc_GmgQaZQ-3kqkfY8GKpbqGLXBj5zXbIl4tO1ZA) because this type of auto-adjustment does not happen to all images, just certain dark ones (which I underexpose on purpose to preserve certain skintones).

Please help!

Edit: I note that a similar question was asked here (https://discussions.apple.com/thread/7033700) , but it was with regards to Yosemite and RAW images. mine are jpegs so I don't know why this auto-adjustment is happening Super alarming as it seems to be permanent and no way to undo?!

MacBook Pro w/ Touch Bar (2018 or later)

Posted on Jan 6, 2019 12:03 AM

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Answer 1

Jan 6, 2019 8:35 AM in response to tsodium

Could you post one sample original file that shows a problem, to some place like dropbox so we can test?

Are these images taken with a camera? Which one?

What do you see if you do Command-I in Preview for one of these files?

Maybe the color model recorded in the file does not match the real one in which it was recorded.

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Answer 2

Jan 6, 2019 2:01 AM in response to tsodium

Are you using the default color profile?

Try opening the same files in a different user account. Same issue?

Try opening when running in Safe Mode. Same issue?

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Answer 3

tsodium Author

Level 1

4 points

Jan 6, 2019 12:39 AM in response to tsodium

Edit 2: I tested this out to see if it was isolated to preview, by getting a fresh backup file of the same image and opening / importing it directly to Lightroom (without opening it once with preview or finder at all). It imports in the washed out manner.... BUT when I preview it, it initially once again shows the original 'darker / more contrasty' image. WHat's going on!

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Answer 4

tsodium Author

Level 1

4 points

Jan 6, 2019 2:10 AM in response to Luis Sequeira1

I'm not sure what using a default color profile means so I'll go google that (I haven't changed any color profiles / settings on my mac...? it's fairly brand new). I've tried opening the same files with a test user account with same issues (and also tried dark vs light modes etcetc).

I"ve noticed curiously that if I view the file using the little eye-icon, and I pinch the image (after the auto-filter is applied without my permission), you can see the original. It flicks back to the auto-adjusted image when you let go however. This does not work if i open the file in Preview fully. and after a few goes, the eye-icon one stops doing this as well.

I also note that I took a screenshot of that dark original image and preview does NOT auto-edit the screenshot!!

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Answer 5

tsodium Author

Level 1

4 points

Jan 7, 2019 2:07 AM in response to Luis Sequeira1

Firstly thanks heaps for taking the time to help me. Apple support hasn't been really helpful and it looks like I might just return this machine out of frustration / distrust at this point but I'm currently still looking into it, namely:

I'm not sure what you mean re color model recorded not matching the "real one in which it was recorded" - my camera is a canon 5d mark iii and captured in jpeg (i.e. no RAW involved for these). Everything was RGB -- I've tried to link below to a sample image. Colour profiles are the sRGB IEC61966-2.1

https://drive.google.com/file/d/1HCMLMMLLR68aMLYpFpkDpJ7Lbos9Sbov/view?usp=sharing

I've compared the images to my very old MacBook Air - and barring the huge screen resolution / quality differences, now I'm almost feeling like the slightly washed out version IS the "original", matching the macAir view (when I switch the MacBook pro's screen colour settings to sRGB IEC61966-2.1?) But it's just very confusing given this flickering with preview / eye-icon view.

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Answer 6

dialabrain

Level 10

136,457 points

Jan 7, 2019 3:32 AM in response to tsodium

Just to add, when you display 8bit/72dpi images on a 24bit/144dpi screen, there are bound to be translation issues. Plus different apps will use different profiles. Also, you can't compare an image on two different displays with different characteristics and glean anything useful.

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Answer 7

Jan 7, 2019 6:25 AM in response to dialabrain

For me, it looks the same in Preview as in Quicklook, or Safari, Pixelmator or even Chrome.

A mere adjustment in Preview (command-option-C, and click Auto Levels) is enough (IMHO) to greatly improve it (sorry, not a photographer, so I may well be off base here); add a tiny bit of extra saturation and you get something that, to me, looks a lot better.

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