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L
Longshot408
Participant
January 20, 2020
Answered

lossy vs. non-lossy file formats

  • January 20, 2020
  • 3 replies
  • 1503 views

Evening all,

 

Quick question regarding prefferred file formats. I'm getting more seriously into photo editing and wanted to know the best approach moving forward to handling my photo library. Thus far I've been correcting things in PSE, then saving as a .PNG file because I heard they do not degrade in quality if saved repeatedly. I've also heard that they display sharp lines and details better, which is why .PNG is preffered for images with text or logos and such.

 

My question is, if all I am archiving are photos of "daily adventures" (vacations, day trips, etc.) and shots of my friends and I from my Pixel 3a, should I be concerned about saving in .PNG? If I view a .JPG and a .PNG on a high dpi and color-accurate monitor, could I tell the difference between the two? I'm trying to plan for the future as much as possible...and if better monitors (which I'll be getting soon) and repeated saving (as in backing up to an external drive) will reveal imperfections, I would like to know.

This topic has been closed for replies.
Correct answer Greg_S.

For photos, as between jpg and png, you should use jpg.  With large megapixel images, any compression, even with multiple open and saves, can hardly be noticed in most cases, even with high dpi monitors.  See this thread for more of a discussion.

 

As for repeated saving of jpgs in backups, this should have no effect on the photo quality, unless maybe the backup compresses the file.  Just copying a jpg file does not cause a compression.  It is only when you open and save a file in the jpg format that compression takes place.

3 replies

Walter_H
Walter_H
Legend
January 20, 2020

Hi Longshot408,

 

If you're getting more seriously into photo editing, why not also consider a better camera than a Pixel 3a? I have a Pixel 3 XL and I consider most photos taken with it to be disposable. My main camera for keeper photos is a Canon EOS Rebel SL2 w/ several different lenses.

--Walter in Davie, FL
Greg_S.
Community Expert
Greg_S.Community Expert
Community Expert
January 20, 2020

. . .   I'm sure Ansel Adams or Annie Leibovitz could take better images with a disposable camera than I could take with a $50,000 Hasselblad! 

 

The best camera is the one you have in your hands when a photo opportunity arises. 

    Walter_H
    Walter_H
    Legend
    January 20, 2020

    Greg, I did NOT say disposable "camera". My Pixel 3 XL is always in my pocket and my Canon SL2 is usually nearby. I've taken many more pics with the Pixel than with my SL2, but my best pics always come from my SL2. The only edits I ever do to pics from my Pixel are a crop or resize.

    --Walter in Davie, FL
    T
    Test Screen Name
    Legend
    January 20, 2020

    You can try a simple test. Get a photo and save it at the LOWEST JPEG quality. Can you see the difference? I expect you can. Now, save it with the highestd quality? Can you see the difference? I expect not. (Either way, you do not need accurate colour or high resolution to see; in fact high resolution might make it harder to see). 

     

    Now consider this: if you keep editing, each time it damages a bit more. So, eventually you'll end up with something more like the lowest quality. This doesn't apply if you just view it or copy it or back it up, but simple things like rotating in Windows will do it.

      L
      Longshot408Author
      Participant
      January 20, 2020

      Thanks so much!! Wasn't aware that repeated backing up wasn't the same as editing and re-saving, or that compression is hardly noticable with high-res images. I will stick to .jpg then!

      T
      Test Screen Name
      Legend
      January 20, 2020

      "Wasn't aware that ... compression is hardly noticable with high-res images." Actually I see that's what I said but it wasn't what I meant. My point was that you might find it hard to see the damage if your screen is high resolution (because the damage is small and detailed). The damage is just as bad.

      Greg_S.
      Community Expert
      Greg_S.Community ExpertCorrect answer
      Community Expert
      January 20, 2020

      For photos, as between jpg and png, you should use jpg.  With large megapixel images, any compression, even with multiple open and saves, can hardly be noticed in most cases, even with high dpi monitors.  See this thread for more of a discussion.

       

      As for repeated saving of jpgs in backups, this should have no effect on the photo quality, unless maybe the backup compresses the file.  Just copying a jpg file does not cause a compression.  It is only when you open and save a file in the jpg format that compression takes place.

        MichelBParis
        MichelBParis
        Legend
        January 20, 2020

        "You can try a simple test. Get a photo and save it at the LOWEST JPEG quality. Can you see the difference? I expect you can. Now, save it with the highestd quality? Can you see the difference? I expect not. (Either way, you do not need accurate colour or high resolution to see; in fact high resolution might make it harder to see). 

         

        Now consider this: if you keep editing, each time it damages a bit more. So, eventually you'll end up with something more like the lowest quality. This doesn't apply if you just view it or copy it or back it up, but simple things like rotating in Windows will do it."

         

         

         

        See:

        http://regex.info/blog/lightroom-goodies/jpeg-quality

         

        There has been hundreds of posts of people testing repetitive jpeg savings in normal conditions:  original pixel size 8 to 12 megapixels from today's cameras - relatively low compression (8 - 10). Indeed, anybody can try this and judge by himself.

        More important today is if you shoot jpeg or raw and if you use a non destructive workflow. It's obvious that it's not a good idea to delete or overwrite your original images, whether jpeg or raws. A temporary edit stage involving layers has to be saved in psd or tiff. Parametric edits made in ACR don't create any loss, even from a jpeg. There is no compression "loss" when changing the ACR settings like color balance, crop, vibrance or clarity, sharpness and noise. No need to save a psd version; maybe save a jpeg version set according to your output requirements.

         

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