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Old Nov 17, 2003, 3:05 PM   #1
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Default Converting JPG to TIFF in PC

Bill Sams mentioned that if one shoots SHQ then best to 'save' the original JPG in TIFF format in the PC and that a 2mb SHQ file would become approx. a 12mb TIFF file in PC conversion.

How does such a converted JPG to TIFF file compare to a picture shot originally in TIFF format? I was thinking you loose the 'ultimate' detail of an originally shot TIFF picture once you shoot in a compressed (SHQ) mode. Is it really possible to re-capture that detail by PC conversion?
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Old Nov 17, 2003, 3:18 PM   #2
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You wouldn't gain anything. It's only if you're currently editing the photograph...personally though I'd use the program's proprietary file format which would save masks and layers as well. The only time I've used tiff was on the camera for that money shot (since my camera doesn't have RAW)...otherwise I avoid it.
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Old Nov 17, 2003, 3:39 PM   #3
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if you shot in jpg and and then save as a tiff it will only save the image that exists at that point. in short you can't save what isn't there. there can be no improvement without the additional data lost in the original jpg compression.
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Old Nov 17, 2003, 6:24 PM   #4
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Default JPG conversion to TIFF

Mike_Peat: This 'newbie' understands 'avoiding' TiFF , using it for a money shot and not gaining anything by conversion as the other reply confirmed. This all makes sense.

BUT you qualify by adding "It's only if you're currently editing the photo." and I'm lost on that one.

Soooo if one can NOT recapture what is lost in the JPG compression then is there any advantage/reason to save a JPG in Tiff on the PC???


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Old Nov 17, 2003, 7:05 PM   #5
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Quote:
is there any advantage/reason to save a JPG in Tiff on the PC?
If you edit a JPEG and then save it, what was already compressed once ends up being compressed a second time. If you keep on doing this, working only on the photo in JPEG format, eventually the "lossy" compression becomes obvious and the quality degrades. On the other hand, if you convert the JPEG to TIFF or, if you're using Photoshop, to PSD, no matter how many times you edit and save the photo, you'll lose nothing in it.
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Old Nov 17, 2003, 8:12 PM   #6
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Okay, force me to profer ingnorance (PSD???).... great explanation of re-editing and degrading JPG's

But please amplify "if you're using Photoshop, to PSD, no matter how many times you edit and save the photo, you'll lose nothing in it."

Here I'm lost....can you explain the above namely how to lose nothing working in photoshop where I am (1) working on a JPG and/or (2) I'm working on a TIFF ( that I've converted from a JPG)?
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Old Nov 17, 2003, 8:19 PM   #7
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PSD's tend to be a bit larger than TIFF's, because the format itself isn't compressed (I think) so a JPEG saved in PSD is like an image in stasis, it doesn't change unless you directly edit the layer its on.
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Old Nov 17, 2003, 8:31 PM   #8
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Here I'm lost....can you explain the above namely how to lose nothing working in photoshop where I am (1) working on a JPG and/or (2) I'm working on a TIFF ( that I've converted from a JPG)?
Sure, you can edit that JPEG the first time it hits your computer, but when you go to save it, don't save it as a JPEG. Save it as a PSD if you're using Photoshop. This way you won't be compressing it a second time.
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Old Nov 17, 2003, 8:52 PM   #9
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When you open a JPG in any viewer or editor the file is decompressed. In the case of a 5Mp image that turns out to be 14.1Mb regardless of the compression of the original JPG. The image decompresses to 2560 X 1920 pixels and that comes out to 14.1Mb.

There was some quality loss in the original compression in the camera. The higher the quality you use the less the degradation. Iím guessing you are referring to a 4Mp camera with your numbers and a 2Mp SHQ JPG is the highest quality JPG. There is still some degradation compared to extracting a TIFF or raw file, but not a lot.

You do not get any more quality loss by decompressing the image in the viewer or editor. But if you save the image again as a JPG you introduce more compression artifacts. If you save in any loseless format like TIFF, PNG, PSD or TIFF with LZW or ZIP compression you lose no more quality. You can open and save a TIFF a hundred times and it is just like the first one without any loss of quality due to compression. So if you save that original JPG after working on it in a loseless format you donít lose any more quality.

The compression artifacts tend to be enhanced with resizing, sharpening and resaving again as a JPG. I think it is good advice to save in a loseless format once you open an image and change it in any way. If you donít change the image there is no reason to disturb the original JPG on the hard drive. That JPG is the highest quality you can get from that image once the camera compresses it. Converting it to TIFF only increases the storage size.

The reason a PSD file is larger is just that it saves the layers and some other information. Both TIFF and PSD are loseless.

There are some advantages to raw that make it superior to TIFF as well as being a third the size. I prefer raw to any other format, but I would shoot in superfine JPG before TIFF in most cases if those were my only choices. If the camera had only fine it would be a tough choice Ė an inefficient large file or compression artifacts.
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Old Nov 18, 2003, 1:19 PM   #10
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:lol: Great explanations. If understanding correctly, I can input 100 pix from media card to HD, then open/view/close them UNLTD times w/o and loss so long as NOT editing or otherwise saving as JPG?

So all best versions of edited pix stay in the PSD VAULT! Perfect original JPGs can stay on HD as perfect JPGs.

Don't want to push my questions into a 'mini course' but perhaps a few sentences on 'if and when we must go back to a JPG version?

IS IT necessary when emailing and resizing for email? Being certain to rename the file so as to RETAIN AND NOT OVERWRITE THE PSD PICTURE.? Or is it better to re-size, save again as PSD and email the PSD???? Thanks.
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