1994.12.15 14:24 "Re: TIFF File Naming Conventions/Standards?", by Bill Davis

Ever try to view multiple single page images that should viewed as one document? It can be impossible without the creator application or without opening each images individually. (Not cool!)

>From an Object Oriented standpoint, a set of multiple single images should be a single entity. If we consider other file formats, the Postscript format comes immediately to mind. In Postscript, an entire document can be collected into a single file.

The problem with multiple images for TIFF is that the format was designed for a single image. The name says it all: the I stands for Image instead of document, image group, etc.

When there are multiple images in a single file, the standard is clear that they are variations of a single image. Only the first one must be read by a compliant TIFF reader.

I would rather see an extension to the TIFF standard which allows either:

1. flagging of subsequent IFD's to indicate if they are to be considered alternate images or additional images (e.g. by adding an image number, so you can have 3 versions of the first image and 2 versions of the second image, etc.)
2. a TIFF collection which is a file with a new type which has an IFD containing references to embedded TIFF files (e.g. a TIFF definition for an archive file which could define a TIFF level N compliant reader).

Having a convention for the use of names in various operating systems is nice, but the same convention can be used to have a group of GIF files or a group of text files. Putting something like that in a library causes so many OS dependencies that the extension and maintenance of the TIFF specific parts of the library would inevitably suffer.

Does anyone know if the group that determines TIFF standards has considered this issue? Is this something that the standard may address in the future or is it considered permanently out of the scope of the standard?

Bill Davis
wdavis@dw3f.ess.harris.com