[Gamoe]

As my photo collection grows, I am starting to require some sort of compression to fit it onto a regular DVD. I know I can zip files directly from the Finder. But, what is really the best (most efficient, more space-saving) compression format available for Mac OS X?

[macintologist]

high quality JPEG is the most practical and efficient format. If you're a pro and need lossless compression then go with TIFF.

But yea, go with high quality JPEG. It's like an AAC file, compressed but you really can't tell the difference unless you're an audiophile who has nothing better to do but buy expensive speakers and listen for tiny compression artifacts.

[macintologist]

I'm sorry I think I misunderstood you initially.

The type of file-compression you should use (if any) depends on the files you're talking about. If it's apps, then you should use .sitx

But since you're talking about photos, are they JPEG? If yes, then you don't even need to compress them as a zip or whatever, they are already compressed. If they are something else like TIFF, EPS, BMP, RAW or something else then you should try compressing them to .zip or .sitx, or compressing the images themselves to high quality .jpg would do a better job.

[clam2000]

I belive the best compression currently is called LZMA and is available only from a tool called 7zip.

I don't belive that there is a gui version of the tool available for mac right now, although the command line version does exist.

I belive that gzip is slightly better than zip overall, and it's probably the easiest solution.
(plus a tarball makes it easy to add and extract single files in a archive after it's created, so you can access a picture without uncompressing the entire archive)

[osxrules]

If you want the best image compression format then if you don't mind loss in quality, JPEG is best and I find quality setting of 80% retains a decent amount of quality and still saves a good amount of space.

If you don't want to lose any quality then PNG gives the best lossless compression. Using compression like zip or sitx won't save much space and will just take a long time to compress and decompress. Plus, if you put them direct onto the DVD, you might be able to play the DVD in a DVD player.

I personally use tiff with lzw compression because Photoshop has pretty bad PNG support.

[mduell]

If your photos are already in a compressed format (jpeg, gif, png) you won't be able to get much additional compression.
Buy dual layer DVDs or just use more than one disk.

[Tesseract]

As has been said, if your photos are in a compressed format already (jpeg, png, gif, tiff+lzw), additional compression won't do much good.

bzip2, 7zip, sitx, and RAR are known for having good compression algorithms, if you really want to try one. Make sure it really does give an appreciable savings before you go compressing your entire photo library, though.

[Gamoe]

Ah. I see. So the consensus is that if the photos are already in a compressed format, like JPEG, there will be little to no reduction in size with further compression. I do have files in TIFF and Photoshop formats, but the vast majority of them are in JPEG format, and I need to shave off 1.05 GBs to get it to fit on a DVD. So, I guess that probably won't work.

Now, I can't use dual-layered DVDs on a stock eMac Superdrive, right?

[SkullMacPN]

Originally Posted by Gabriel Morales

Now, I can't use dual-layered DVDs on a stock eMac Superdrive, right?

Your 1 GHz eMac can not burn dual layer DVDs. Newer eMacs (May 2005 or newer) with a SuperDrive have dual-layer capabilities.

[Gamoe]

Originally Posted by SkullMacPN

Your 1 GHz eMac can not burn dual layer DVDs. Newer eMacs (May 2005 or newer) with a SuperDrive have dual-layer capabilities.

Yep, that's what I thought. Oh, well...

[d.fine]

Get an external hard drive, more space than a dvd... and you can take it with you if that's what you're looking for, taking your picture library with you.

[osxrules]

Originally Posted by Gabriel Morales

Ah. I see. So the consensus is that if the photos are already in a compressed format, like JPEG, there will be little to no reduction in size with further compression. I do have files in TIFF and Photoshop formats, but the vast majority of them are in JPEG format, and I need to shave off 1.05 GBs to get it to fit on a DVD. So, I guess that probably won't work.

If you list the images by size and find the largest ones, it will likely be the tiffs and psds. Make sure the psd files don't have layers stored (unless you need them in which case you can compress them too. Otherwise flatten the file). You can batch convert the tiffs etc. to jpeg using graphicconverter. I like graphicconverter because it has an image compare function so you can check to see if your images are losing a lot of quality in the compression. That's why I find 80 to be a good compromise between quality and size. It should save you the space you need.

Another thing to check is if any of your files have resource forks attached. This is one reason to avoid the graphicconverter file browser thing. Not the dialog I mean but the icon view. It adds massive resource forks which you should strip using the terminal command:

cp /dev/null /path/to/file/rsrc

don't use that if you're not sure because it copies null onto the resource fork and if you get the path wrong then you could overwrite the file. I use On My Command to do it.

[glyph]

There's JP2 and lurawave (LWF). They'll compress your photos even more. I think you can even compress entire directories with a command-line utility. The downside is not everyone will have a plug-in/utility to view these files with - if you wanted to share them.

http://www.luratech.com/products/index.jsp

[Uncle Skeleton]

TRUE: lossless compression of individual compressed image files will not gain you any space

FALSE: lossless compression of a large folder of compressed image files will not gain you any space.

If you have a large number of small files, you lose space due to file system overhead from each file. For example, I had a ~2GB (~13,000 files) folder of image files yesterday, but when I tried to burn it on DVD it read as about 2.5 GB (too big with other stuff on the DVD), probably due to different block sizes between HFS+ and UDF. No problem, said I, I'll just make a disk image of the folder, then the DVD will see it as one big file and block size won't matter. Well Disk Util's "compressed dmg" format stored the whole folder in 1.5 GB. A substantial savings even over the HFS+ version.

So in short, you can save space by compressing a folder of many small files into one large file, and doing so in disk image format will save you having to decompress the whole thing for use.

[glyph]

Here's another tool that looks interesting:

http://www.stuffit.com/mac/index.html

It claims to compress jpgs 30% without reduction in quality.

[Uncle Skeleton]

up to 30%. It's meaningless marketing language.

[Gamoe]

Well, I tried zipping the files, and it did save some space, but not nearly enough to fit it onto a DVD. As for Stuffit, I'm not convinced it will do much better and one has to pay for it, so I'm not going there. I don't think it's a good idea to use a proprietary and rare compression type (like the luratech one) if one is trying to ensure accessibility of the data. I would be willing to try some of the UNIX compression tools, but I also doubt these would help much more, from what I've seen.

Originally Posted by osxrules

If you want the best image compression format then if you don't mind loss in quality, JPEG is best and I find quality setting of 80% retains a decent amount of quality and still saves a good amount of space.

Though there are practical limits, computer storage sizes are rapidly increasing, and if it gave me significantly more quality, I wouldn't mind having LARGER image sizes, as quality is more important to me than size, specially when these are photos one would want to have and see, say twenty or thirty years from now. How silly would it look then that you seriously sacrificed the image quality for a few extra megabytes or gigabytes? Of course, this does present problems now when backing up to external mediums.

I've actually been thinking of storing images in RAW format (which my camera can do), but I'm still not completely sure of its advantages over JPEG, and it seems to have various (compatibility, accessibility, etc.) drawbacks. But, that's another topic entirely, of course. As of now, I simply use my camera's JPEG images.

Originally Posted by osxrules

If you list the images by size and find the largest ones, it will likely be the tiffs and psds. Make sure the psd files don't have layers stored (unless you need them in which case you can compress them too. Otherwise flatten the file).

I used to tweak my photos with Photoshop, which is why I have quite number of Photoshop files. All have layers, which is why I've kept them in Photoshop format, so I wouldn't want flatten the files.

Now I don't bother tweaking, with rare exception, because there are just so many and it is so much work to do so with each and every photo, apart from leaving one with multiple versions of the photos (the original, the photoshop and the final).

Originally Posted by osxrules

Another thing to check is if any of your files have resource forks attached.

Stripping resource forks is an interesting idea. I know most Mac OS X apps don't use resource forks, but what effect does stripping them have? Surely they aren't there without reason?

Originally Posted by d.fine

Get an external hard drive, more space than a dvd... and you can take it with you if that's what you're looking for, taking your picture library with you.

I DO have an external HDD. In fact, I have an external drive, the same capacity as my Mac's internal drive (160 GB-- I upgraded it) solely for the purpose of serving as a backup. However, with things like my photos, I like to have additional backups, just in case. I don't have physical copies of most of my photos, and I prefer to be on the safe side with such personal data which I could never recover from anywhere else (unlike songs, etc.).

Originally Posted by mduell

Buy dual layer DVDs or just use more than one disk.

I looked into dual-layered DVDs (DVD+R) and it seems finding actual DVD+R medium is a bit difficult. Apart from this, it seems they have low recording speeds and higher prices (per MB) as well. And, of course, I'd need to buy a drive.

I suppose I'll have to simply use more than one DVD, but this makes things a little more cumbersome and difficult, as one has to somehow divide the files between DVDs. However, at this point, there may not be a better solution that doesn't require considerably more expense.

[glyph]

Originally Posted by glyph

There's JP2 and lurawave (LWF). ..

I downloaded the plug-in.....it only installs on older Macs. What a piece of crap.

[osxrules]

Originally Posted by Gabriel Morales

I used to tweak my photos with Photoshop, which is why I have quite number of Photoshop files. All have layers, which is why I've kept them in Photoshop format, so I wouldn't want flatten the files.

Now I don't bother tweaking, with rare exception, because there are just so many and it is so much work to do so with each and every photo, apart from leaving one with multiple versions of the photos (the original, the photoshop and the final).

If you don't need to tweak them then keeping the layers will waste a lot of space. But if you do really want to keep them try compressing the layers if you haven't already. It's an option when you save the psd files - this doesn't lose quality.

Stripping resource forks is an interesting idea. I know most Mac OS X apps don't use resource forks, but what effect does stripping them have? Surely they aren't there without reason?

The resource fork is a Mac thing and shouldn't be used for files but some programs like GraphicConverter use it to store image icons. In some cases, this can double the file size. I use FileBuddy to search for files with a resource fork and then strip them using On My Command. The resource fork isn't the same thing as the information that programs like Photoshop store in the image header such as EXIF data.

I looked into dual-layered DVDs (DVD+R) and it seems finding actual DVD+R medium is a bit difficult. Apart from this, it seems they have low recording speeds and higher prices (per MB) as well. And, of course, I'd need to buy a drive.

Dual layer DVD has a DL at the end. DVD+R is just a different format from DVD-R. You get DVD+/- R DL. But you're right they are more difficult to get hold of and more expensive.

I suppose I'll have to simply use more than one DVD, but this makes things a little more cumbersome and difficult, as one has to somehow divide the files between DVDs. However, at this point, there may not be a better solution that doesn't require considerably more expense.

I would fill as much of a disc as possible and then burn the rest to another disc. Then when you get more photos, you can copy the small amount from the second disc, add to it and burn another disc and throw away the old second disc. I'd actually try and not fill a DVD up completely. I find the outer edge of DVDs tend to be more prone to errors so I wouldn't put much more than 4.35 GB on them.

It might be easier to use DVD RW for the second disc. DVD RW aren't really any less reliable than DVD - it's true in theory that RW last about 30 years as opposed to 100 years for R but in 10 years time, we will have switched to Blu-Ray, HD-DVD or fluorescent discs, which hold about 10-20 DVDs worth of space.