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October 2004
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2004.10.05 08:43 "Re: BigTIFF extension issue", by Andy Cave
Hi Chris. > Photoshop PSD -> 8 byte offsets became PSB because users couldn't > understand why it wouldn't open in older versions of Photoshop (having > been mostly compatible from 3.0 to 7.0). A good example. Albeit of an internal single company format as opposed to an external public format. So slightly different. > PDF and EPS are examples where the version number didn't change, but older > apps may break or not read the files. That's not an example of where the extension changed. Although it is a good example of where older apps would break (for various reasons - PS1 went though various revisions without any version changes - color extensions,... and then PS2 added new operators, ... and...). > JPEG -> JPEG2000: same group, same goal, different format, different > extension This is a good example of where a new file format (jp2) was designed and the contents (encoded stream) changed, so it did need a new extension. Not the same thing we're discussing. > Most of my other examples are along the lines of PSD -> PSB, but aren't > image formats. So, we only have one 'similar' example with Photoshop. Did no-one have any comments re my mail about defining the bigtiff spec in a backwards compatible way? If we did this, then the question on extension becomes mute. _andy. PS Perhaps its about time we added a version number tag to TIFF if there's not one already.