Hi Tom!

In my opinion plain TIFF would be the format of choice for all the criteria mentioned.
Using none of the features supported by non-ancient versions of Photoshop like i.e. multi layers and omitting any kind of compression you should be fine for the forseeable future.

Regards Markus

Am 25.10.2006 um 17:39 schrieb Tom Purl:

Hi. I still use a film 35 mm SLR to take most of my "real" pictures, and then scan them into my computer using Xsane and edit them use Gimp.

I would like to start archiving these images in a format that adheres to
the following requirements:

* Fidelity - The higher the better. I would like the images to be of a
high enough quality where they could be easily used to create a clear 8
x 10. I realize that other factors affect the clearness of a large image (such as film speed and such). File size isn't a factor.

* Compatibility - I would like the freedom of being able to send my images to multiple developing companies and have them all be able to use
the image. What's a good standard format that most "real" developing companies accept?

* Bitrot - I would like to use a format that will probably be around for
a while. I know that no format is completely future-proof, but I don't
want to convert these images more than once every couple of decades if possible.

Thanks in advance for any help!

Tom Purl

Just curious, is there a reason that PNG is a bad choice for this?

Lossless compression seems like it'd be a great advantage and it isn't a fly by night file format.

On 10/25/06, Tom Purl wrote:

Thanks Markus and Chris for the advice!

I checked out the Wikipedia page on the JPEG format, and found this excellent link on image degradation when you edit a jpeg:

* http://www.jmg-galleries.com/articles/jpeg_compression.html

It appears that at the very least, I should first convert my image into a TIFF before I edit the image.

* Fidelity - The higher the better. I would like the images to be of a high enough quality where they could be easily used to create a clear 8 x 10. I realize that other factors affect the clearness of a large image (such as film speed and such). File size isn't a factor.

It looks like both TIFF's and JPEG's will work equally well here, as long as I convert the image to a different format (like TIFF or XCF) *before* I edit it.

* Compatibility - I would like the freedom of being able to send my images to multiple developing companies and have them all be able to use the image. What's a good standard format that most "real" developing companies accept?

I'm pretty sure that my local Work Camera will print photos from a TIFF, and I'm pretty sure that Flickr will do it too. I just tried uploading a TIFF to Snapfish, however, and it was rejected. Thank goodness it's a trivial task to convert it to a JPEG using ImageMagick.

* Bitrot - I would like to use a format that will probably be around for a while. I know that no format is completely future-proof, but I don't want to convert these images more than once every couple of decades if possible.

Both formats seem equally well-suited in this regard.

Markus Kamp said:

Using none of the features supported by non-ancient versions of Photoshop like i.e. multi layers and omitting any kind of compression you should be fine for the forseeable future.

Thanks for the tips! If I start working with layers or anything like that, I'll be sure to save the file as a Gimp XCF.

"Alan Wolfe" writes:

Just curious, is there a reason that PNG is a bad choice for this?

Lossless compression seems like it'd be a great advantage and it isn't a fly by night file format.

Does PNG support 16 bit per channel? If not then TIFF is probably the better choice for those.

And if there is the possibility that the pictures need to be modified they should not be saved in a lossy format to begin with. Lossy formats introduce artifacts that are normally not visible. But certain image enhancing operations can "enhance" those, too.

Matthias

On Wed, Oct 25, 2006 at 08:37:55PM -0400, Matthias Julius wrote:

"Alan Wolfe" writes:

Just curious, is there a reason that PNG is a bad choice for this?

Lossless compression seems like it'd be a great advantage and it isn't a fly by night file format.

Does PNG support 16 bit per channel? If not then TIFF is probably the better choice for those.

Yes, it does. I do medical diagnostic software, and we use the 16-bit support of PNG every day.

Jeff