Save TIFF as ZIP or LZW compression
- Thread starter fiatlux
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Lukas Engqvist
Well-known member
if the image is line art with large flat colours then LWZ compression wich is run length compression will work best. If you have a photographic image I think ZIP will give better compression.
fiatlux
Well-known member
I've heard that one of these (can't remember which) can introduce artefacts like lines in the image. Is that true or just an old prepressman's tale?
FL
mattbeals
Well-known member
JPEG would introduce artifacts into the image (lossy). ZIP and LZW are lossless compression. However JPEG2000 has less obvious artifacts and can achieve high levels of compression. You can also use JBIG compression for monochrome art.
Give JPEG2000 a try, it has a "lossless" setting which is much like ZIP/LZW compression levels in my experience.
Give JPEG2000 a try, it has a "lossless" setting which is much like ZIP/LZW compression levels in my experience.
leonardr
Well-known member
If you're doing this for archival purposes, then I would recommend the international standard for such things - PDF/A (PDF for Long Term Archiving - ISO 19005).
Leonard
John Clifford
Well-known member
In this day and age I'm actually surprised that you feel you need to compress at all. ZIP and LZW are lossless but they don't compress very much. Jpeg is lossy which means that data is "thrown away" each time you compress the image. Not considered a good idea as multiple compressions will be like xeroxing something over and over again, each generation becomes worse and worse.
With storage as cheap as it is today, why would you even consider compression? You can purchase a 1.5 Terabyte external hard drive at Costco for about $150. That will hold an awful lot of archival images.
The safest way to go is to keep images in their original, pristine, format.
With storage as cheap as it is today, why would you even consider compression? You can purchase a 1.5 Terabyte external hard drive at Costco for about $150. That will hold an awful lot of archival images.
The safest way to go is to keep images in their original, pristine, format.
Hi All,
My suggestions / comments:
1. Why use PDF for an image when TIFF is so much simpler. If it's an image, store it in an image format - PDF is overkill for that. If it's a 'page description' with text & images, then use PDF/A.
2. Use lossless compression such as LZW or ZIP. ZIP always compresses more than LZW, but takes longer and is not always supported (actually, usually it is theredays). So I'd go for LZW.
3. Do use compression - in my experience you can always get some compression with LZW, even if it's only a factor of 2 or so. This gains you, not only in terms of disk space, but also in terms of speed - it is faster to read a smaller compressed file and decompress it than read a larger uncompressed file (assuming you read it once...).
4. FTR LWZ is NOT run length encoded, but who cares, just use it.
5. If your RIP baulks at a compressed image., it's a c**p RIP - either get a new one or upgrade it. Any good RIP such as Hqn should handle all (properly) compressed images.
Regards,
Andy.
My suggestions / comments:
1. Why use PDF for an image when TIFF is so much simpler. If it's an image, store it in an image format - PDF is overkill for that. If it's a 'page description' with text & images, then use PDF/A.
2. Use lossless compression such as LZW or ZIP. ZIP always compresses more than LZW, but takes longer and is not always supported (actually, usually it is theredays). So I'd go for LZW.
3. Do use compression - in my experience you can always get some compression with LZW, even if it's only a factor of 2 or so. This gains you, not only in terms of disk space, but also in terms of speed - it is faster to read a smaller compressed file and decompress it than read a larger uncompressed file (assuming you read it once...).
4. FTR LWZ is NOT run length encoded, but who cares, just use it.
5. If your RIP baulks at a compressed image., it's a c**p RIP - either get a new one or upgrade it. Any good RIP such as Hqn should handle all (properly) compressed images.
Regards,
Andy.
Last edited:
Gregg
Well-known member
The problem with this is that your archive is only as good as the $150 drive you purchased at Costco. If that drive craps the bed, then your done.
One thing I have noticed re: files with LZW compression is that our legacy files (specifically Quark 4) are now having problems reading TIFs with LZW compression. In the usage panel they all have "No Extension" errors next to them.
John Clifford
Well-known member
So where do you archive that you can be sure that what you archive to won't crap out? My main point was that storage is cheap, so why compress. Compression is just to save space so you can store more on a given medium.
Archiving is always a problem. What technology will still be around in 5, 10, 20 years. I've dealt with stuff that was archived on paper punch tape, 1" mag tape, 8" floppies, magneto-optical disks, cassette tapes, 3.5" floppies, syquests, bournoulli's (sp), etc. The least of my problems is a hard drive crapping out.
Archiving is always a problem. What technology will still be around in 5, 10, 20 years. I've dealt with stuff that was archived on paper punch tape, 1" mag tape, 8" floppies, magneto-optical disks, cassette tapes, 3.5" floppies, syquests, bournoulli's (sp), etc. The least of my problems is a hard drive crapping out.
Steve_S
Well-known member
We use a LaCie 2-Big with redundant Terabyte drives that are hot swappable. If one takes a crapper, buy another and drop it in. The next day you are back to double-safe. It's pretty cheap solution and doesn't take a lot of tinkering. The last thing you want to do is have a labor-intensive solution for something that is not generating revenue.
John Clifford
Well-known member
Fiatlux doesn't say how he's currently archiving, but I'll bet that since he's asking about compression that he doesn't have it on a RAID. Probably CD or DVD.
I agree that a hot-swappable RAID would always be a good idea, but most folks here don't have those kinds of resources. They don't even have RAIDs for their primary data (where it's <i>really</i> critical.
I agree that a hot-swappable RAID would always be a good idea, but most folks here don't have those kinds of resources. They don't even have RAIDs for their primary data (where it's <i>really</i> critical.
ZIP and LZW won't harm the image in any way - just as good as uncompressed except for possible support issues in non-Adobe software. Compressing generally requires more processing than decompressing - LZW or ZIP shouldn't slow down a read too much, but the initial save will probably take longer. As Andy mentioned, compressed images can often be read faster than uncompressed images, especially if you have a fast processor and the compression ratio is high.
In my experience, ZIP has always been smaller than LZW for all types of images. Saving RGB, CMYK, Lab and multi-channel images with per-channel order instead of interleaved will increase the compression ratio (often significantly) because there is stronger correlation between the pixel values within one channel than between the channels.
A RAID5 array, 2 disk RAID1, or manual mirroring of 2 drives often provides a stronger sense of security than it deserves. Consider that when one disk fails, the whole system is then critical (i.e., you can't stand to lose a single disk) until you rebuild the failed disk using the others. The rebuild process will potentially put more stress on the remaining drive(s) in a matter of hours than they would normally receive in a month, and may be accessing many sectors of the remaining disks that have not otherwise been accessed in a long time. If another disk is close to failure, then it is likely to fail during the critical rebuild process. I use RAID6 on two identical servers (no tapes, optical disks, etc.).
In my experience, ZIP has always been smaller than LZW for all types of images. Saving RGB, CMYK, Lab and multi-channel images with per-channel order instead of interleaved will increase the compression ratio (often significantly) because there is stronger correlation between the pixel values within one channel than between the channels.
A RAID5 array, 2 disk RAID1, or manual mirroring of 2 drives often provides a stronger sense of security than it deserves. Consider that when one disk fails, the whole system is then critical (i.e., you can't stand to lose a single disk) until you rebuild the failed disk using the others. The rebuild process will potentially put more stress on the remaining drive(s) in a matter of hours than they would normally receive in a month, and may be accessing many sectors of the remaining disks that have not otherwise been accessed in a long time. If another disk is close to failure, then it is likely to fail during the critical rebuild process. I use RAID6 on two identical servers (no tapes, optical disks, etc.).
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