Since macOS 15, Preview auto darkens the image when you do certain edits. Why? Maybe just leave my images alone and let me do what I want?
I do not find anyway to turn this nonsense off.
MacBook Pro (M2 Max, 2023)
Adding any shape, line, arrow or text. Draw, Add Signature,
Click on Circle Marker Tip, Most any function in that menu.
Also when clicking on Adjust Color, it does not appear that the spectrum analyzer shows any changes, but it clearly darkens light areas. After macOS 15 update, it would pop up a box that would explain something, which I clicked away and said do not show.
I assumed that this nonsense would be corrected with a new update to the OS, that was an exercise in futility.
This seems to ONLY happen on maybe HEIC (possibly RAW format but I have not tested that).
HEIC contains meta data for exposure and such that Preview/macOS is thinking it needs to correct.
If I get the image from iPhone, then convert to JPEG via the Quick Actions Menu, Preview does not seem to modify the brightness of those images.
Unbelievably irritating.
I'll see if I can upload an image to show the difference.
Try changing the Window Background to Default by pressing the "Reset" button, to see if that helps.
Preview > Settings > General.
Otherwise try a a safeboot that can fix many anomalies in macOS.
Start up your Mac in safe mode - Apple Support
The one on the left was an HEIC image. The one on the right was the HEIC image edited, then saved as a PNG. What I meant by in Focus, if you have more than one image open in Preview, or any app for that matter, the one selected is the one in Focus. Also, I have reduced transparency enabled so the background doesn't effect the images as much. In any case, on my M3 iMac, editing an HEIC image does not appear to be darker on my screen.
Last but not least, HEIC images are a compressed lossy format. So it's not possible an edited image will be identical seeing the edited image will be re-compressed. But since it now has edits, it will not be compressed in exactly the same way. It's just one of the reasons to maintain maximum quality, it's best to stick with lossless formats. If that makes sense.
Above Process:
original.heic copied
copy.heic
Open original and copy
draw line on copy, makes photo darker
Placed both Previews next to each other, then did a screen cap.
On on right is darker, with the green line.
In closing, you can always file a bug report from the feedback page.
To this point, the native format that iPhone sends to macOS on airdrop is HEIC, and the native format of the image from the iphone camera is HEIC, unless you enable raw.
Thus we are forced to use HEIC in cases from iphone.
HEIC does have some advantages, but this "smart" BS is hard to troubleshoot.
If I only screen capped the notification that it would "make the photo darker when adding edits" or some such message.
Funny how no syntax online can search and find this notification message that I have found.
Typed Green, but meant Yellow.
Not sure how you "unfocus" a window in Preview.
Both images are displayed side by side.
Regarding your images, You said you didn't work with HEIC so assumed neither were HEIC.
Why are you asking a question? What are you expecting to discover with an answer?
I have no idea which is which file type visually. They are both PNG's if I attempt to download, I can only assume that they are converted when uploaded to png for this forum.
If you are not editing an HEIC, then you are not following the question as presented.
Seems to ONLY be an issue with HEIC.
Neither were selected "in focus" as the screen capture keystroke takes them both out of focus.
You are focusing on the wrong parts of this. Before macOS 15 none of this happened.
If you don't get a popup that Preview is going to "do something to the image" then it is not happening or that message was checked to not show again on your system.
Identical is not what I am asking for, it should be understood that when "editing" an image by adding text or other graphics inside of Preview, the image is not identical.
What we are talking about here is brightness. It automagically reduces the brightness when edits are made.
It did not do this before macOS 15, there is a notification box that explains (although with no details).
No where in the apple ecosphere does it indicate that this was changed in preview that I can find, outside of a notification box when it happens, which if clicked "do not show again" then you never see it.
As for compression, this happens before the file is saved. It does it in some magical manner based on some nonsense brightness factor which cannot be turned off or controlled by the user.
This happens on every picture, in HEIC format, if you place any edits on it.
Sticking with Lossless format would be great but the default file type from iphone is HEIC, and not all applications support "lossless" in the Apple Raw Format.
I could also go into the points that editing on macOS and iOS do not net the same results, as on iphone this does not happen, and you can revert to original on iphone, which you cannot do on macOS. This is not relevant in this case outside of this only happens on macOS.
It should not matter but this system is a MBP M2 Max, and a newer processor on an iMac should have no bearing on the way that Preview operates.
Just to be complete, Preview is version 11.0 (1069.3.3)
I will boot up a new MBP, Intel and see if I can recreate or screen cap the notification box.
drop_table_user wrote:
Neither were selected "in focus" as the screen capture keystroke takes them both out of focus.
That's incorrect as you can see the top title is greyed out and not in Focus…
The same two HEIC images…
What "certain edits"? I haven't seen it darken an image.
That does not change the above indicated problem, making edits still darkens the image.
Still haven't heard what kind of edits. Just to add, what format are the files you are editing?
I'll have to take a look. I rarely ever work with HEIC images.
Okay, I'm not seeing the change you refer to. Maybe someone else will.
FWIW, side by side before and after edits…
macOS Preview is automatically darkening image on edit
