Z
Zak
Zak said:Afaik, GIF is not used as a graphical format inside PDF. It is
probably compressed as a "TIFF" with Cittfax or LZW compression.
"TIFF" is between brackets, because the embedded stream is also not
a complete TIFF file, just contains the compressed graphics and
some extra information like scansize, colordepth, color channels,
etc.
What happens under the hood in your PDF creation really depends on
the PDF engine you're using. Many engines actually resize your
graphics to match the PDF DPI resolution. If you're an experienced
programmer you could try to generate the PDF yourself, with the
images in full resolution. The PDF specification is open and can be
found on the Adobe website.
Nils
Hi Nils and others. I understand now that when I create a PDF from a
image file that the format of the image file is not used inside the
PDF. Instead some other format is used in the PDF (which Nils kindly
suggests may be a specialized form of TIFF).
It is this conversion from my image file format to the internal PDF
format which I want to be done smoothly. I am on XP and I am
wondering if it is better to start with a GIF or a JPG or BMP or
whatever to feed into my PDF creation utility.
I should say that I am starting with a hard copy of a document
created on a word processor. I want to avoid artefacts, unecessarily
jagged lines, moire effects and all that stuff which might come from
transforming from an "awkward2 image format to a PDF.
My PDFs will be for public distribution. I have preferred to scan to
a GIF file rather than a TIFF because I have assumed that when I
circulate the basic image file among certain people that the best
balance between image size and the best chance of them being able to
see the file is a GIF.
To me TIFF feels a bit specialized. For example, I never see a web
page with TIFF images but I see lots of pages with GIFs.
Also there seem to be various compression options for a TIFF (group 3
or 4, LZW, JPEG deflate, none) which might makes it even harder for
me to know what to choose as a common format! The Wikipedia says
documents are often scanned to TIFF group 4 but is that something
which has the best chance of being seen on various PCs in various
organisations that I might need to send it to?