Preview App - Unable to Invert B&W Portrait PNG

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Level 1

4 points

Preview App - Unable to Invert B&W Portrait PNG

I've been trying to Invert the colors of a black and white portrait that I previously removed the background of and converted to PNG from JPEG using the Preview App. As per instructions given in videos on YouTube and answers to other related questions asked here within the Apple Discussions community I have attempted using the "Adjust Color" feature (which I used on earlier iterations of the image file to remove the color, simplify the layers, and increase the contrast between shading layers) to move the Black (Left) and White (Right) adjustment sliders to the opposite sides of the adjustment range, but whichever level I adjust second stops when it reaches the point of the level I adjusted first. The two simply will not pass by each other allowing me to Invert the Black and White levels to the opposite ends of the adjustment spectrum. The middle slider for adjusting mid-tones will pass either without issue. Has the ability to Invert colors been prevented intentionally through updates or is something about my previous edits, file type, or user error the culprit? Thanks.

MacBook Pro 13″, macOS 15.0

Posted on Oct 26, 2024 1:37 PM

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Answer 1

Old Toad

Level 10

216,232 points

Oct 26, 2024 3:41 PM in response to tharoost

Is this what you're trying to do?

Give this a try: boot into Safe Mode according to How to use safe mode on your Mac and test to see if the problem persists. Reboot normally and test again.

NOTE 1: Safe Mode boot can take up to 3 - 5 minutes as it's doing the following;

• Verifies your startup disk and attempts to repair directory issues, if needed

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Prevents Startup Items and Login Items from opening automatically

• Disables user-installed fonts

• Deletes font caches, kernel cache, and other system cache files

NOTE 2: if you have a wireless keyboard with rechargeable batteries connect it with its charging cable before booting into Safe Mode. This makes it act as a wired keyboard as will insure a successful boot into Safe Mode.

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Answer 2

Old Toad

Level 10

216,232 points

Oct 27, 2024 10:01 AM in response to tharoost

Safe Mode is kind of a "first responder" type of fix and does the following:

• Loads only required kernel extensions (prevents 3rd party kernel/extensions from loading)

• Deletes font caches, kernel cache, and other system cache files

If a cache file gets damaged it can cause unusual application performance. Preventing 3rd party apps from loading in the background can also identify a potential part of the problem. Good luck

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Answer 3

tharoost Author

Level 1

4 points

Oct 26, 2024 9:20 PM in response to Old Toad

The video you posted shows what I have been trying to do, but am not able to. The high tone slider and low tone slider will not pass by one another, the mid tone slider seems unaffected and will pass by the other two and vice versa. When I adjust the Left slider past the mid tone slider across to the opposing end of the adjustment range, dropping it about 25% short of the end, I then click the right most slider to do the same thing towards the opposite direction, but when it reaches the slider i just dropped it stops like it hit an invisible wall. The left and right sliders refuse to cross paths with each other.

I'm not seeing how booting into safe mode is relevant to not being able to invert colors in the Preview App.

Thanks for the response.

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Answer 4

tharoost Author

Level 1

4 points

Oct 26, 2024 9:45 PM in response to Old Toad

It should also be noted that the image was a JPEG color portrait taken with a Pixel 7 Pro. The file was then moved to the MacBook Pro, opened in Preview, deleted the background with "Smart Lasso", and used "Adjust Color" tool to remove the color by adjusting the saturation to a value of "0". The file was then saved and auto-converted to a PNG file. I'm not very familiar with Preview App or the intricacies of graphic art and photo editing software, and am not sure if the above listed edits are the reason why I'm running into the inversion issue. My goal is to make an inverted black and white of the portrait so when I print the image onto a type of inkjet printable 2-ply graphite paper (has a white top sheet to make the image visible) then the highlights/reflected light will be blacked out, but the lows and mids will be white and grey. Then to transfer the image to my substrate of choice, I will apply high pressure to the white areas when coloring them in with a ball point pen and medium pressure with a shading pencil to the grey areas to transfer a lighter coat of the graphite paper to the substrate. When I pull the paper off the image will have transferred to my substrate accurately in both shade and orientation, while leaving the highlights nice and bright.

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Preview App - Unable to Invert B&W Portrait PNG

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