File Size and File Type

Discussion in 'Digital Photography' started by wheelhot, Nov 19, 2008.

  1. wheelhot macrumors 68020

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    #1
    Hi,
    Well can someone explain to me why would you save a picture in TIFF rather then JPG or PNG or it doesn't matter?
    I know that in web most pictures is saved under JPG and sometime PNG but how about photographs that you keep?
    A TIFF picture is sized at 27mb while the same picture in JPG is only 2.4mb, that's a lot of difference.
     
  2. richard.mac macrumors 603

    richard.mac

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    #2
    i think a TIFF is lossy like WAV on a audio CD or FLAC and JPEG is compressed which sacrifises the image quality. PNG keeps an images transparency if it has it.
     
  3. wheelhot thread starter macrumors 68020

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    #3
    Aaaah, so it means that PNG and JPEG will produce same quality images unless transparency is involved? and TIFF is something like universal RAW saved format?
     
  4. Digital Skunk macrumors 604

    Digital Skunk

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    #4
    More like TIFF is uncompressed and there is no quality loss if you open it and save it again.... no compression whatsoever.

    JPEG is compressed and every time you save it it will compress again.
     
  5. bocomo macrumors 6502

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    #5
    bingo

    also TIFFs can be 16 bit and support layers
     
  6. wheelhot thread starter macrumors 68020

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    #6
    Thanks for the tip guys cause I made a HDR picture and its saved as TIFF with a whopping 20MB so that is a lot. Anyway, why can't Photoshop save a TIFF image as JPEG?
     
  7. Digital Skunk macrumors 604

    Digital Skunk

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    #7
    It can, just go to save as instead of just save. Either way, 20MB TIFFs are quite small. When you get a 16 bit TIFF file of a 21MP image with lots of bright colors you are talking more like 256MB. You can hold that in RAM, but your processing power will be greatly decreased depending on your machine.
     
  8. GT41 macrumors regular

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    #8
    You need to go image->mode->8bit RGB to be able to save in JPEG as far as I know... but someone can correct me if I'm wrong.
     
  9. MisterMe macrumors G4

    MisterMe

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    #9
    TIFF is most certainly a compressed image format. Unlike JPEG, however, it uses lossless compression.

    Read and be wise.
     
  10. bocomo macrumors 6502

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    #10
    so that's why i have the option to use "No" compression instead of LZW, RLE and JPEG?

    the lossless compression options are certainly valuable but not necessary
     
  11. wheelhot thread starter macrumors 68020

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    Nov 23, 2007
    #11
    Thanks misterme. I don't usually read WikiPedia on terms cause I won't fully understand what it says, I prefer forum for that.

    Aaah, now I know why Pro photographers who post-process will own a MacPro as their working machine. That's huge, I think my MBP (w/ 2GB ram) won't be able to run fluidly with that much of information especially when I'm running, iTunes, Safari, Vuze, Adium at the same time :D.

    Using Photomatix to generate change in a large size photograph already took a few seconds to render and Photoshop -> lens blur in accurate mode take like seconds to change the look of the picture if I change the settings (most of the time I use the quick mode until I'm quite happy with how it looks, only then I change to accurate ;))

    JGEG don't support 16-bit?
     
  12. Digital Skunk macrumors 604

    Digital Skunk

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    #12
    Read your own sources.

    "the TIFF using lossless compression (or none) may be edited and re-saved without losing image quality; other TIFF options are layers and pages."

    You can't save a 16 Bit JPEG, you can convert them to 16 Bit in post, I doubt that would add anything to the IQ even if adding filters, and then you will have to save it as something else.

    Sorry, Edge100 gave the simple answer.... :D
     
  13. Edge100 macrumors 68000

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    #13
    Yup, though I'm not sure how many pros are doing all that while editing...

    Get 4GB in that MBP if you can; it makes a big difference while working in PS.

    Nope. JPEG is 8-bit per channel (i.e. 24-bit RGB).
     

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