15 Feb
2010
15 Feb
'10
11:14 a.m.
Shoppa, Tim wrote:
Tim,
Thanks for the lesson, but I am quite aware of those points already and
I was pretty clear when I posted and said that my source documentation
was a raster image. I'm using PDF for ease of distribution.
Also, I object to the redefinition of "100% zoom" in Acrobat Reader,
which was the source of my confusion last night. I was looking for
confirmation that this is indeed the behavior that PDF viewers have.
When I say
'Zoom 100%', I expect each bit of my image to be displayed
with no scaling. Well, Acrobat Reader doesn't work that way. AR
assumes screen resolution, so what was a 400 dpi bitmap at 100% zoom on
AR gets downsampled to 72dpi for display purposes. To get back to see
individual pixels you have to zoom to 555% or something nutty like that.
I tried it and it looks like all of my pixels are there. Can anybody
else confirm this (bad) behavior?
Bad? PDF's are fundamentally a VECTOR format. A vector format designed around
typography where the most natural unit since long before computers has been the point
(=1/72 inch).
PDF documents, it so happens, can include bitmap images at arbitrary scalings.
Vector formats natively have NO KNOWLEDGE of a pixel and in fact when you include a
bitmap image in a PDF (which is kinda bastardized because it does have some actually quite
thorough bitmap support) it can be scaled so that a pixel in the bitmap is any arbitrary
size in number of points.
If there was any "bad behavior" it may have been... Adobe putting support in
PDF's for bitmaps?
Most current display devices just happen to be raster formats showing bitmaps, but my gut
feeling is that this shortcoming will be corrected and we will go back to vector display
devices Real Soon Now. How soon? In fact I'm going to go use my Tek 4014 right now
:-)
Tim.