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RHOPKINS13
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What you’re describing is just compressing in a ZIP file. Zip files are lossless, you have nothing to worry about. When you throw a JPG in a zip file, and then extract it later, you’ll get the exact identical JPG back.

You only have to worry about jpg’s lossy compression if you’re using a photo editor like Photoshop, GIMP, etc. “Compressing” it in a zip changes nothing. Moving or copying it doesn’t lose quality either.

THE MASTERMIND
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Norgur
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As many others have said, only resaving the image with another jpg compression will degrade quality. What are you using to view the images with? Also, your workflow for looking at.those images/encrypting them sounds rather convoluted. May I ask why you do it that way? Is encryption important to you or is it something else? The constant zipping and unzipping sounds unsafe (so much copying, archives can corrupt) and insanely time-consuming.

Just renaming them to PNG will change nothing at best and make your viewer unable to open the images at worst.

THE MASTERMIND
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Norgur
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Where do you store those files? I’m not familiar with the abbreviation msd

THE MASTERMIND
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You have misunderstood this. Saving a file from an image editor or viewer repeatedly will degrade it. Putting a single saved file in countless zips will not.

Atemu
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Don’t re-encode lossy formats.

What do you mean by “save” as in “copy the file to the encrypted container” or “open the file in a picture editor and saving it”? The former won’t re-encode, the latter likely will.

Renaming a file won’t change its content and therefore won’t change its format.

If the pictures are important to you, make sure they’re backed up appropriately. For even remotely critical data, the rule of thumb is 3 copies across two different mediums with at least one copy at a different location.

Re-encoding MP3s will also degrade quality. Storing them in a ZIP file won’t re-encode them though.
Transcoding an MP3 to m4a will degrade its quality too. The opposite is also true; if you’re downloading music from Youtube for instance (M4A, OGG), don’t convert it to MP3.

The discriminator here is whether lossy compression is applied which is distinct from lossless compression. As the name implies, it loses information in the process.
JPG, MP3, M4A, OGG and many other common formats use lossy compression.
ZIP and PNG use lossless compression; files added to a ZIP file can always be turned to the exact same files again from an encoding standpoint.

THE MASTERMIND
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A file does not deteriorate and you can’t just change extension to change the file type. Jpgs are fine

THE MASTERMIND
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The issue you described can occur due to repeated cycles of editing and saving jpeg images and closing the editor in between.

If i’m editing an image with an editor and i keep saving periodically as jpeg, while the editor remains with the file open, it still has the original before-degradation image so even if i save 10 times as jpeg, the final result is being compressed only once.

However, if I save, close the editor the and then reopen the same file again for more editing, the software has to work with the “photocopy” I saved before, and is this cycle is what could degrade the image.

When you work with image editing, you save your work in a lossless format and only export it as jpeg the final copies that you won’t be editing.

Same goes for mp3 files.

But remember, you can open those files anytime to watch/hear them without any degradation.

Yes, every time you compress the jpg again it will lose quality because jpg is a lossy format (Someome else already explained the difference between lossy and lossless) but putting it in a zip won’t compress it again. Since zip compression is lossless no data is lost, so you can decompress and recompress as often as you want without losing data. Same goes for png, it’s lossless too. Recompressing a jpg as a png (E.g. by opening it in a photo editor and saving at as a png) doesn’t make sense tho, the data was already lost when saving as jpg, so the jpg and the png will be the exact same picture. The png will just be a lot bigger in size.

THE MASTERMIND
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Yes but png or jpg files take the data of an image and save them in a more efficient way inside a file. A zip file takes any file and saves it in a more efficient way. Putting a png inside a zip will compress the compressed image file but since zip compression is lossless, you’ll get the the exact same compressed image file back when you decompress the zip again. Same goes when putting a jpg file inside a zip.

Renaming the files wont change the filetype.

Also the images won’t loose quality for looking at them, opening or moving them. Only if you reapply the jpg compressing algorithm over them.

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@d3Xt3r@lemmy.nz
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‏‏‎ ‎

THE MASTERMIND
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File compression and image compression are different things. In lossy image compression you throw out some data when re-saving the file and that’s not reversible; in file compression you don’t throw data out, so it’s reversible. It’s like rewriting a sentence in shorthand. All the information is still there, and if know the shorthand you can rewrite it back to plain English again (decompressing the file).

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