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Old Apr 25, 2004, 11:36 PM   #1
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Default Will ZIP compression affect image quality on TIFFs?

Once I transfer all my JPEGs over from my camera, I batch process them as TIFFs so I will keep the image quality good without it going bad after editing them, or opening them over and over.

The thing is after shooting nearly 2000 pictures and about 75% of them being TIFFs, I have a total of about 10 GBs, on two 30 GB HDDs. Can I compress them with a ZIP so they won't take up so much space. Will it affect the image quality if I save and open them as TIFFs but with the ZIP compress?
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Old Apr 26, 2004, 12:13 AM   #2
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Zip is lossless.

Some programs give you an LZW option for saving the TIFF this is another lossless algoritm similar to the one used in ZIPs. So it may be more convenient to save this way.
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Old Apr 26, 2004, 11:00 AM   #3
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Quote:
Originally Posted by CastleDude
Zip is lossless.

Absoultely correct!

Some programs give you an LZW option for saving the TIFF this is another lossless algoritm similar to the one used in ZIPs. So it may be more convenient to save this way.
Sometimes this "compression" results in larger files - Even when it does compress, there is only a minimal saving.

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Old Apr 26, 2004, 10:23 PM   #4
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That is certainly true if the TIFF is already compressed (or if you tried to compress a jpg) but I bet it is rare if the TIFF has not already been compressed.

Uncompressed TIFF doesn't even use run length encoding, which is the easiest method of compression out there.

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Old Apr 27, 2004, 2:47 PM   #5
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Default Re: Will ZIP compression affect image quality on TIFFs?

Quote:
Originally Posted by CheckSix
Once I transfer all my JPEGs over from my camera, I batch process them as TIFFs so I will keep the image quality good without it going bad after editing them, or opening them over and over.
Why not keep the original jpeg (which is already compressed)??
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Old Apr 27, 2004, 4:07 PM   #6
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Default Re: Will ZIP compression affect image quality on TIFFs?

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Originally Posted by ironchef
Quote:
Originally Posted by CheckSix
Once I transfer all my JPEGs over from my camera, I batch process them as TIFFs so I will keep the image quality good without it going bad after editing them, or opening them over and over.
Why not keep the original jpeg (which is already compressed)??

I do keep the original JPEG, just like keeping a 35mm from film. However, I resave each picture as a TIFF because after someone has opened them up in Adobe PS, and resave them, the JPEG compresses more. In other words, each time the save button is pressed, the JPEG is compressed more, and it causes image quality to go from excellent to horrible.

Here's an example, with the original in the upper left corner and the final image in the lower right hand corner...



Keep in mind that is after the image was saved many, many times. JPEGs are "lossy", or the file is compressed at each save. TIFFs are lossless, so when they are saved, they are not compressed, and no image information is lost.

I save as TIFFs so I can edit them a lot without losing quality.
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Old Apr 27, 2004, 9:55 PM   #7
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I thought some TIFF formats had reasonable lossless compression, but perhaps I saw some non-standard implimentation.

Are PNG or TGA viable alternatives to TIFF. PNG's would have the advantage of being able to be posted directly to the web (even with compression you better have broadband though ).
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Old Apr 27, 2004, 11:04 PM   #8
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Quote:
Originally Posted by Effen
I thought some TIFF formats had reasonable lossless compression, but perhaps I saw some non-standard implimentation.

Are PNG or TGA viable alternatives to TIFF. PNG's would have the advantage of being able to be posted directly to the web (even with compression you better have broadband though ).
That's a good question...

If I take TIFFs on the camera they turn out to be about 14.1 MB. If I resave my JPEGs as TIFFs they turn out to be like 12 MB.

I'll have to read up on PNG/TGAs
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Old Apr 28, 2004, 12:52 AM   #9
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As far as I know, there is no lossey TIFF compression. First came uncompressed TIFF, then came TIFF extentions that added a compression. There are currently... 2 or 3 different compressed TIFF formats. Not all programs support all compressed TIFF formats, though.

They all do a decent job at compressing the picture, I believe.

Is PNG or TGA 16-bit capable? TIFF is. I believe that TIFF has some support for layers... but I don't really know for sure.

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Old Apr 28, 2004, 1:50 AM   #10
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There is a lossy TIFF compression method using the JPEG compression method. Not very commonly used, but if you ever run into a TIFF which size is similiar to a JPEG you chances are very high. Actually, this compression method is completly useless since EXIF (JPEG stream using TIFF format information blocks) does it better.

PNG can do 16bit, but it is not a very good format for digital images. The compression is not optimal, the predictor is not optimized for real world images when compressing. You can try for yourself to save a LZW-TIFF as a PNG. You won't see a big advantage.
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