Reducing file size for storage

[Ann Helgeson]

Our local museum has a photo collection of about 1500 grayscale images that have been enhanced/fixed in Photoshop 5. At the moment they are located on one woman's hard disk and we have to store them/back them up in an accessible format. CDs seem the best solution. Each .psd file is 5-7 Megs and that adds up to a lot. Is there a better format to store these photos that doesn't take up so much space yet doesn't lose the detail of the image? We want to be able to print a high quality 8x10" print for patrons of the museum who want copies.

I'm sure this is an elementary question for all you PS tyros.

Ann Helgeson

[YrbkMgr]

The only "raw" image format that may give you better file sizes would be TIFF when used with compression (an option in save as tiff within photoshop).

Other strategies include using compression utilities, but you lose the convenience of popping in the CD and just looking - they'd have to be extracted, if only temporarily, before they could be viewed.

[Phosphor]

"I'm sure this is an elementary question for all you PS tyros."




You do know that "tyro" means amateur, right? Just a little vocabulary lesson so that you don't inadvertantly insult someone in the future...I knew what you were going for, so it's cool, Ann.

Anyway....I'm pretty much with Tony (YrbkMgr) on this. Yes, you'll need a bunch of storage space...I figure about 18 full CD's worth, which really isn't that bad. If I were running the show, I'd want these files easily accessable, and I wouldn't risk any quality compromise that would come from image compression of any kind. FILE compression, perhaps, if you're that concerned about storage space. I'd just stick with native PSD format (or TIFF....but since you're asking the question, you may not want to learn and deal with the optional issues involved) and tough out the time and space requirements necessary to save them that way. 18 CD's don't take that much space, nor time to burn. Make 2 or 3 sets and keep them in separate physical locations.

[Michael B. Field]

The museum may want to invest in a dvd burner; you'll cut the 18 discs down to 4.

[Ann Helgeson]

Thanks folks (and sorry about calling you tyro's; I thought that meant expert, but it turns out to means exactly the opposite! Phosphor gets a gold star in his/her book for today). I guess I belong in a museum myself. The hard disk in my first computer had 20 megs, so a 5 meg picture seems large. We'll leave them in .psd format.

Ann

[Cheesefood]

Wait a second. Help me where I'm wrong.

If you do all the work on them in TIFF format, then convert them to JPEG's at the highest quality, you should be able to maintain the original look and reduce file size. Since these will be burned to a CD, there's no chance of re-editing the originals, so all future work can be done after re-converting to TIF format.

This is more of a question than an answer. Please explain the flaws in my theory.

[YrbkMgr]

Cheese,

I think your rationale is reasonably sound, but there is reticence in general to remove any data from an archival image.

I think functionally, it wouldn't likely make a difference, but philosophically, no one likes to archive an image that has lossy compression applied, no matter how little if they can avoid it.

That's my two cents anyhow...

Peace,
Tony

[Cheesefood]

I think functionally, it wouldn't likely make a difference, but philosophically,
no one likes to archive an image that has lossy compression applied, no
matter how little if they can avoid it.




The photo CD's we purchase always have their images in JPEG format.

If the photos in question ar B&W, there would be the minimal amount of lossiness, correct?

[YrbkMgr]

Well, that depends on the situation.

I would never purchase JPG images, if I could avoid it. What if you want to create JPG's? You either use the image, as supplied on CD, or introduce additional lossy compression.

I know of no data that suggests JPG "issues" such as artifacts and the like are any less likely to be on B/W/Grayscale images than anything else. I'm not saying it's not true, I just have never heard it.

Your safest answer is to use a file format that has had as little degredation as possible. IMO, that would be a TIFF or A PSD (or gif if applicable).

That's just my two cents...

Peace,
Tony

[YrbkMgr]

I wouldn't argue with the source images being JPG on CD - personally, I feel goosey about it, but you obviously haven't had issues, and so it is probably sound.

In regards to the JPG compression issue, I'm not convinced that the JPEG Spec mentions color as a determinant; It may, I'm just not aware of it. That is to say, I don't know to what extent the algorithm used in JPG compression differentiates "color" or not. It doesn't seem to me that it would, since Black, is a color, white is a color and 128 gray is a color. If you mean that it would use the Mode of the image (indexed, grayscale, RGB, etc), I suppose it's possible, I've just never heard it.

For whatever it may be worth, I archive 1,500 - 3,000 images per day, 7 days a week. I use as "raw" a data type for archiving as I can - functionally, since we're a scanning house, that means scanned PSD's. My philosophy is, in five or 10 years, I don't know what image editing will be like, and what my process may have introduced that will, potentially, be noticable. Since I can't control for it all, I personally prefer to stay away from all lossless methods. I view JPG as a FINAL output format, and so we handle files accordingly here.

I'm not saying that I'm right, just that's the philosphy we use...

Peace,
Tony

[Cheesefood]

I'm not saying that I'm right, just that's the philosphy we use...




That's probably the best philosophy to use. The nature of the question leads me to believe that these aren't what one would call Important Historical Documents. No offense to what you're archiving, Ann, but the fact that you came here to ask leads me to believe that the museum isn't too concerned with how lossless the format.

And since the question posed was one of maximizing storage and mentions that 5.5 is the software being used, I'm pretty sure we're not talking about archiving an original Ansel Adams.

[Ann Helgeson]

Thanks everyone for the interesting answers. I didn't notice any Ansel Adams originals in our collection but these photos are VERY important documents for future generations in our little town and we want to do the best we can to preserve them. After all, without these pictures future generations might not be able to find out who the King Hog was in the 1953 Hogeye Festival... Important stuff like that. Some of the photos were reproduced from glass negatives made early in the 20th century which almost went into the trash when a new owner took over an old building. Hope that won't happen to our CDs!

Thanks again folks.

Ann

[LenHewitt]

Cheese,

>>If the photos in question ar B&W, there would be the minimal amount of

lossiness, correct?<<

The compression would be inefficient - JPG compression doesn't work well on
greyscale.

The best way of compressing greyscale is as a 256 colour GIF....No loss at
all