saving jpeg

Discussion in 'Photography Beginners' Forum' started by Emerana, Jan 22, 2008.

  1. Emerana

    Emerana TPF Noob!

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    In the online class I am taking, they said jpeg was very 'lossy" and you shouldnt save and resave in that format. Does anyone convert? To what? I have been using jpegs forever, I never knew they were so awful???
     
  2. That One Guy

    That One Guy TPF Noob!

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    do they mean the format you take the photo in?

    i take mine in raw and convert to jpeg. i know many who convert to tiff.
     
  3. jlykins

    jlykins TPF Noob!

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    What they're saying is, that everytime you open and resave in jpeg you loose some clarity/data in the photo. For example if you open a photo in photoshop and add layers, or change contrast, ect. it wants to save it as a photoshop file, if you chose to save as a jpeg the image degrades slightly.
     
  4. EOS_JD

    EOS_JD TPF Noob!

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    Jpg means smaller file sizes and compression that involves the loss of some data. Keep saving and saving and yes you will start to see some degradation but save as a high quality jpg and it will take many saves before you see any difference.

    Honestly do not worry too much about this. Jpg is a great way to get small files out of your PC for sending on the web and printing. Sure it's a lossy format especially if you save as low quality files but 99% of people will never notice a difference even after 10 saves of the same file!

    I shoot RAW and this is my negative. I convert to jpg for printing.
     
  5. RKW3

    RKW3 TPF Noob!

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    Whenever I resave a photo it's always PNG, just because it's lossless.
    downsides of PNG are:
    -loss of EXIF data
    -can't upload to some sites
    -larger file size (I think)
    upsides to PNG are:
    -lossless (can resave it a billion times, stays the same)
    -you can resave your PNG back to a JPEG with no loss of quality.
    -no loss of quality on upload to web.
    -it makes you unique. :)

    I just re-save my pics as a PNG, I'm sure TIFF works too but I havn't tried it for some reason.
     
  6. RKW3

    RKW3 TPF Noob!

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    Actually I have started to see some un-smooth gradients appear after a mere five saves with high-quality JPEG. I guess it doesn't matter with a lot of people if they don't usually resave pics.
     
  7. EOS_JD

    EOS_JD TPF Noob!

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    Not quite right. As soon as you save to jpg you compress the file and lose some quality (how much depends on the quality you save at)!

    There is no way to save a jpg without compressing it and therefore losing some data (albeit very little at high quality settings).

    You can do the same with psd and tif which are also lossless compressed image files.

    Also you should note that to save an image to the web it usually needs to be by a small jpg file (800x600 or thereabouts). By doing this you have just thrown away most of your pixel information in your file and then I guess you save as a lossy jpg file so lots of quality is lost when you save a web image!!

    Not unique either as I sometimes use the png format as it holds transparency info.
     
  8. EOS_JD

    EOS_JD TPF Noob!

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    Yes probably correct but I geuss what you have also done is resize the image - probably for the web.

    A full resolution image will take a lot more than 5 resaves at HQ setting.
     
  9. sabbath999

    sabbath999 No longer a newbie, moving up!

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    I don't EVER use JPEGS in post production, I always save right away to lossless... it only hits JPEG on the very last step.
     
  10. Mav

    Mav TPF Noob!

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    This is why it's best to try to minimize the number of times you re-save a JPG. Usually I do all of my post-processing in DxO in which case it makes all of the adjustments I need and then re-saves once. I save at 97% quality which makes for about the same file size or slightly bigger as the original. I've never noticed any loss in quality. If I'm processing fisheye images, I have to do one additional step of converting them through another application which results in two saves. Never seen any loss in quality from that either.

    If you're going to be doing a very heavy amount of tweaking to one image and not all in one sitting, yeah it's best to save to a lossless format rather than JPG.
     
  11. EOS_JD

    EOS_JD TPF Noob!

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    So you do use jpg ;)
     
  12. JerryPH

    JerryPH No longer a newbie, moving up!

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    PNG, TIFF and RAW are all lossless files, I PP in that and when I have the final product, THEN I convert to JPG.
     

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