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shushustorm

[SOLVED] .jpg compression loses colors at 100% quality

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Hey everyone!

 

I am not positive if this is a bug or not.

 

Most of the time, jpg compression works alright, but sometimes, preserving colors will be a huge issue.

Even when using 100% quality, some images will suffer from an extreme color loss.

Is there a way to avoid this while still compressing the image?

Are there some weird things going on with the color profile?

Or is this to be expected?

 

[EDIT:

Alright, this is a bug of some sort.

If I take a look at the images here in my browser, this issue isn't present. The colors look fine.

However, when I download the images and look at the .jpg files (using space bar in Finder or Preview.app), the color loss is present.

 

Also, I was able to resolve this issue for some files. I don't know the exact workflow for doing so, but it involved copying the image data into an empty file.

Is this an issue of file corruption?]

 

Best wishes,

Shu

Image04_1.png

Image04_2.jpg

Image05_1.png

Image05_2.jpg

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Hi shushutorm

 

What colour bit depth are you using? These look like renders so I'm guessing it may be 32bit. As jpeg is only 8 bit what you could be seeing is the reduction in bit depth. Difficult to tell without an example file to look into

 

Cheers


Serif Europe Ltd - Check the latest news at www.affinity.serif.com

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Hey Chris_K!

 

Thank you for your answer!

I attached 4 images that you can actually download and take a look at. The first of each image is a .png file, the second one is .jpg.

However, when I open both .png and .jpg, they all say the "Document -> Colour Format" is RGB (8 bit).

So even the .png images are only 8 bit.

 

Maybe it's worth noting that I made the original image files (also .png files) using Mac OSX's screenshot functionality (cmd + shift + 3).

Afterwards, I used Affinity Photo to crop the images and save them to new .png files.

Those .png files are the ones that I used to compress to .jpg and the ones attached in my post (including said .jpg files).


EDIT:

Also, the .jpg files even show the whole color range when I open them in Affinity Photo.

It just seems that some applications (including Mac OSX Finder and Preview.app cannot read the whole color range of the .jpg files.)

This happened as well when I uploaded some .jpg files that I compressed using Affinity Photo to my website.

Safari could not show the whole color range of those .jpg files. However, when I attach those files to my posts here, Safari does show the colors.

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Hey! Interesting suggestion! Thanks!

I just tried that and turns out, even the .jpg files exported from Preview lose color when shown in Finder.

However (!!), they do show the full color range in Affinity Photo, even when exported from Preview.

Is this a bug with Finder and Preview after all?

 

Using those two .png files, my tests result in the following:

 

.png files show full color range in

- Finder

- Preview

- Safari

- Affinity Photo

 

.jpg files exported from both Affinity Photo and Preview show full color range in

- Safari

- Affinity Photo

but limited color range in

- Finder

- Preview

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Hi shushustorm

 

If it's off in finder and preview his could be more OS side. There is a known apple issue that they are not displaying colour profiles correctly in general, especially wider gamut ones

 

cheers


Serif Europe Ltd - Check the latest news at www.affinity.serif.com

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It really seems to be an issue with the OS. Just for the record, I am using a 2015 15'' Macbook Pro and OSX 10.11.6.

Can somebody using a newer OS check the images I attached in my original post and open them in Finder and Preview?

Do they show the same colors?

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Thanks for testing! Good to know this is not an issue with Affinity software, but rather OSX just not displaying like it is supposed to.

I guess I am just going to switch to Safari for previewing images from now on. Which may be weird, but I guess it's just a matter of habit.

Hopefully, this gets fixed in future versions of macOS.

For that purpose, I just sent feedback to https://www.apple.com/feedback/macos.html

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