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Hello Leonard,
At 09:34 AM 4/24/2004, Paul wrote:
>Just to clarify I think this is actually very significant. Versions 1-5 of
>Acrobat always displayed at 72dpi this gave us a cross platform format in
>that an image created at 100% 72dpi would appear smaller on a pc in terms
of
>screen mm which is correct.
You are making a number of assumptions that may not necessary be
true here - not the least of which is that the user is ONLY viewing the
document at 100% zoom. As soon as the user changes the zoom factor - OR
if the user's preferences are set to something like "Page Fit" or "Fit
Width", then the image resolution is NO LONGER 72dpi...
I understand that but the issue is that our documents are protected from
changes and we have created files that we want to show our users at 100%.
>Now I have just checked distiller 6 and the PC
>distiller defaults have been changed for "Screen" to downsample to 100dpi
>whereas on a Mac its still 72.
First, I would be quite surprise to find mismatched defaults...
Second, Distiller 6 does NOT include a Screen setting. So
whatever setting you have was created by YOU and NOT by Adobe.
My apologies Leonard, the defaults have changed but it depends how you make
the file. Screen was the job options for version 5 which was 72dpi. This
has been replaced in 6 with an option called "smallest file size" and the
downsample is now 100 dpi and is the same for Mac and PC presumably to take
accoun of the new 96dpi display on a PC. Strangely Indesign has job options
for export and here the screen option is a default at 72dpi. Acrobat itself
does have mismatched default with regard to page display resolution though.
>72dpi downsampled images will be lower quality.
Why would a 72dpi image be of lower quality?
I think you are misunderstanding how Acrobat (and probably other
applications) render information to screen.
I might be mistaken but my understanding is that an image 72 dpi created on
a Mac for example of 1*1 inch contains 72*72 pixels. Now on a pc when
displayed at 100% i.e. 1 inch then the pc will display 96 pixels the
reduction in quality I refer to will be the rendering of the extra pixels
and this will not be quite as good as the original. Under Acrobat 5 this
would not have happened because at 100% Acrobat would have displayed an
image smaller than 1 inch. It is the equivalent of zooming in - you get
pixelation.
Regard
Paul
Leonard
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