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Thread: tiff or jpg?

  1. #1
    Join Date
    Feb 2005
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    tiff or jpg?

    which one is the best in quality aspect?

    I know that tiff takes more space than jpg and also camera takes more time to write tiff format in card. But I would like to know the difference in quality sense.

    Anybody with experience in this area?

    Thanks in advance

  2. #2
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    Mar 2005
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    College Station, TX
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    Cool

    jpg compression causes data loss. the more you compress a jpeg file, the more data is lost. tiff is supposed to be "loss-less", but my understanding is that (at least for large enough pixel counts) you don't notice a quality difference between a high-quality jpeg and tiff, and the jpeg takes up less memory.
    I just want to live happily ever after, every now and then. --Jimmy Buffett

  3. #3
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    My understanding is this: if you are maniuplating a jpg file, it will be compressed further every time you save it. The solution is to work with the tiff file, and then finally convert it to jpg at the end (if file size is your concern).

  4. #4
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    .tiff or .psd

    I only work on tiff copies of the origianl jpegs. The first jpeging, when the camera makes the file after the image has been captured, is hardly noticable if at all. Subsequent jpeg compressions will likely be visible. Photoshop's native format, .psd, works as well but is not as portable. Almost any good printshop can print a tiff and it can be used in layout programs. In design work, I always use tiff files in layouts for printed output.

    In the olden days many people worked in .psd and converted to tiff only for final printing, as tiffs could not be saved with layers. Now that layered tiffs are available, there's not much of a reason to use .psd and then convert. Also, LZW compression on tiffs is not lossy, so feel free to use it every time.

    One way or another though the important thing is to use a lossless file format and to that end, tiff is great. Big, but great.

  5. #5
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    Re: tiff or jpg?

    Quote Originally Posted by Ali_baba
    which one is the best in quality aspect?

    I know that tiff takes more space than jpg and also camera takes more time to write tiff format in card. But I would like to know the difference in quality sense.

    Anybody with experience in this area?

    Thanks in advance
    I've strained my eyes for years trying to see the "loss" in image files because of "fine" JPEG compression. In fact, a couple of years ago someone ran a pixel for pixel test, and found that the TIFF file and the corresponding JPEG file were virtually identical. If you download the JPEG file to your computer, and always do your edits or crops on copies of the original, you'll never go wrong.
    Let a be your umbrella!

  6. #6
    Join Date
    Jan 2005
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    33

    ...but why take the chance?

    John,

    I respectfully disagree with you. While you're correct that compression may not be noticable, each save in jpeg mode adds compression and the cumulative effect is almost always noticable.

    I would recomend taking a look at page 204 of "Real World Digital Photography" by Katrin Eismann. There she has a demonstration using the same picture, each with an increaqsing level of compression to show how the jpeg compression averages the colors of the pixels. The results are pretty clear and quite noticable.

    For many years in the design business jpegs were only used as previews as many wanted no part of compression for final output. Today's jpegs are much better at printing than in the past and as we know from contemporary digital cameras, they can produce stunning output. But adding additional compression doesn't really serve anyone; hard drive space and offline storage (CDs DVDs) is relatively cheap so why not have the best image possible?

    Hey, I wish my Frank (FZ20) had a super fine mode for shooting. I would gladly devote an extra megabyte per file to have even a little less compression than the fine mode that's available now. Not that I have any problems with what I am shooting but overall, the less processing the better. Jpeging is, by nature, a destructive process; and there is no way to retrieve that data, short of going back to the (an) original, after the compression has been added.

    And by the way, I hate the thought that I am disagreeing with you as I have seen your work and it is quite good. Your many posts are right on target and have been very helpful; I have just been taught to use jpeg compression sparingly and feel that's the best information to pass on.

  7. #7
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    Formerly South Wales. Now South Carolina.
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    when an image is saved as a compressed jpeg image then resaved, the following happens:

    1. The image is compressed and saved.
    2. The image is uncompressed and displayed.
    3. The image is re-compressed and saved.

    If the compression algorithm is the same then there's no reason why there should be any noticable difference, assuming the image is saved as 100% rather than as 75% etc.

    Re-saving jpegs can cause loss of quality but not always.

  8. #8
    Join Date
    Mar 2005
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    Sacramento, CA
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    Quote Originally Posted by Rhys
    when an image is saved as a compressed jpeg image then resaved, the following happens:

    1. The image is compressed and saved.
    2. The image is uncompressed and displayed.
    3. The image is re-compressed and saved.

    If the compression algorithm is the same then there's no reason why there should be any noticable difference, assuming the image is saved as 100% rather than as 75% etc.

    Re-saving jpegs can cause loss of quality but not always.
    The problem with the algorithms is that each resave (recompression) actually compresses a bit more....

    Say you start with a Tiff and do step 1. You compressed the file losing some data. Doing step 2 uncompresses the file, but it is not the same Tiff you start with... I think we are all in agreement there.

    Now when you take the new uncompressed image and recompress it, you actually end up with a file that is further compressed. The jpg algorithm things you have a new tiff and is trying to compress it further. Each time you try to save a jpg it tries to compress it further. If it compressed to exactly the same jpg as before, then a jpg should never lose data, and the jpg should never be different than the tiff in the first place. Unfortunately, that is not the case.

    However, I don't doubt that today's jpg algorithms are much better than those of the past. I actually take my photos as jpgs because at least at that initial save there is very little difference from a tiff. At least it isn't enough to bother me. If I use photoshop to work on the file, I will always save the photoshop file as my base point, so any further saving to jpg will in effect be only the 2nd compression. I'm not a professional photographer, so that is fine with me. If I'm going to make a print, I go from the photoshop file to the printer, which means I've only had one compression run. Again that is to my satisfaction.

    Perhaps when I have the money I will think differently, but the idea of camera memory being cheap is relative to what one consider's cheap. I like being able to fit 600 photos on a SD card instead of 100 or less as happens when I go from jpg to tiff. I take too many photos to afford the SD cards I would need. However, I don't mind storing the uncompressed files on a CD that only costs 10 cents later.

    That's what works for me.

    What's important: just understand what is happening when you use jpgs and how important those effects are to you.

    -Erik

  9. #9
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    Question Re: tiff or jpg?

    Quote Originally Posted by eastcoastjoe
    John,

    I respectfully disagree with you. While you're correct that compression may not be noticable, each save in jpeg mode adds compression and the cumulative effect is almost always noticable.

    I would recomend taking a look at page 204 of "Real World Digital Photography" by Katrin Eismann. There she has a demonstration using the same picture, each with an increaqsing level of compression to show how the jpeg compression averages the colors of the pixels. The results are pretty clear and quite noticable.

    For many years in the design business jpegs were only used as previews as many wanted no part of compression for final output. Today's jpegs are much better at printing than in the past and as we know from contemporary digital cameras, they can produce stunning output. But adding additional compression doesn't really serve anyone; hard drive space and offline storage (CDs DVDs) is relatively cheap so why not have the best image possible?

    Hey, I wish my Frank (FZ20) had a super fine mode for shooting. I would gladly devote an extra megabyte per file to have even a little less compression than the fine mode that's available now. Not that I have any problems with what I am shooting but overall, the less processing the better. Jpeging is, by nature, a destructive process; and there is no way to retrieve that data, short of going back to the (an) original, after the compression has been added.

    And by the way, I hate the thought that I am disagreeing with you as I have seen your work and it is quite good. Your many posts are right on target and have been very helpful; I have just been taught to use jpeg compression sparingly and feel that's the best information to pass on.
    "If you download the JPEG file to your computer, and always do your edits or crops on copies of the original, you'll never go wrong."

    Was there some part of that quote you misunderstood to mean that I was advocating re-saving and re-compressing JPEG files?
    Let a be your umbrella!

  10. #10
    Join Date
    Jul 2004
    Location
    Formerly South Wales. Now South Carolina.
    Posts
    7,147
    Quote Originally Posted by emalvick
    The problem with the algorithms is that each resave (recompression) actually compresses a bit more....-Erik
    I don't think that's quite right.

    Try these for more information:
    http://dynamo.ecn.purdue.edu/~ace/jp.../jpegtut1.html
    http://www.w3.org/Graphics/JPEG/

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