I've only just caught up with this thread, so sorry for the delay.
Clive Bonsall <C.Bonsall@xxxxxxxx> wrote:
> The first is "unknown field with tag 700 (0x2bc) ignored". Clicking OK
> brings up a second message: "unknown field with tag 34665 (0x8769)
> ignored".
FYI:
Tag 700 = XML packet containing XMP metadata.
Tag 34665 = A pointer to the Exif IFD.
> What causes the warnings -- is this expected behaviour with TIFF files?
As David has explained, TIFFs contain tags that allow all sorts of extra
data to be included within the file. When programs get a TIFF file to
deal with, there will be a certain number of tags that they will
recognise and some they won't. How the image/output may be affected by
those tags depends on what the tags are. For example, if your TIFF,
saved from Photoshop, contains colour profile data, is then processed by
an application that ignores that profile then final output when printed
may be effected from what you were expecting.
> I find I can save the pictures (line art) out of OPW as Draw files and
> get round the "warnings" problem, but the files are just as big (if not
> bigger) as the original TIFFs.
The reason they are bigger than the original TIFFs is that they won't
have any LZW compression.
Out of interest, you say these pictures are line art - so have they
been created at 1bpp colour depth? If not, and they are say at 24bpp,
then you have images that are excessive in size for the data they need
to contain. The reason I ask, is because of the tag that contains
the Exif IFD pointer, which suggests to me that the image may have
originated from a 8 or 24bpp JPEG.
--
Gavin Crawford
email: gav@xxxxxxxxxxxxxxxxxxxx
web: www.crawford-print.co.uk
