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On 30 Mar 2006, at 22:06, [EMAIL PROTECTED] wrote:
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As usual when I read these sorts of discussions I end up more confused
-
perhaps someone can explain better.
If I generate say a 800 x 800 pixel image in a program, it is just
that.
It has no size in the file. It has no business being assigned a size in
any image header.
If I display it on my computer screen I can tell to display as 800 x
800
pixels (say), full size, or scale it by interpolation to any size (in
pixels) that will fit on my screen. It still has no ruler size in
inches
or any other unit (what is this "inch" anyway?). How big is my 1280 x
854
pixel screen? Who cares?
If I submit it to a publisher for a paper, they will decide how big to
print it (usually too small in my experience). All they need is
sufficient
detail that they can degrade it to their preference.
It's only if I send it to a printer that the ruler size becomes
relevent,
and that should be decided (by me) when I print it.
Am I missing something?
In my opinion, no, you are absolutely right.
The size only becomes relevant for the printer. My suggestion always
is, if you know how many inches the final print is expected to be,
to make sure you have enough pixels = 400 x (inches-for print) to
ensure good quality printout. The actual 'ruler size' is still not
relevant
if you have enough pixels and any Adobe gizmo can resize the image
without resampling to make the pixels fit the right print size.
Final comment: I am a bit fed up with people asking for a new computer
because their PP files are 0.5 Gb and they cant handle their
presentations.
Your PP file will be massive if you include to it in one slide a panel
of i.e. six pictures of 4000x3000 pixels each, which would give 210
Mbytes panel. If now you resize these before to a size that would much
any beamer, ie 200x150, the total size is 0.48 Mbytes.
A.
Phil
Understand your point reg. image resolution, Tim.
But I got perfectly good 300 dpi image resolution of my .png by
resizing
and manipulating in Photoshop. If you uncheck the 'resize image' box
while saving an image, it constrains the resolution along with the
image
proportions and you get what you want. This works because it has
worked.
All the journal folks that howl murder at lost resolution have liked
my
pretty pictures :)
Who taught me this? A crystallographer who got this knowledge in turn
from his wife, a graphics artist who makes cover pictures for a living
for children's books.
Now printer woes wrt colours and resolution are incomprehensible to my
puny brain. I'm told there's only one solution for printers - dealing
with a baseball bat....
Ofcourse, Warren just wrote his suggestions, which takes care of our
concerns...
Raji
Tim Fenn wrote:
On Wed, Mar 29, 2006 at 04:47:47PM -0500, Raji Edayathumangalam
wrote:
Here's a suggestion. Many moons ago, PyMOL would write out pictures
with
a default resolution of 72 dpi.
To circumvent this, I used to reset the size of the output image in
PyMOL to get the final resolution you want in the foll. manner.
Say you want a fig. with final resolution of ~ 300 dpi at a final
size
of 4-in by 3-in.
I always notice people do this, but it doesn't actually get around
the
issue of print resolution versus image resolution (and no, the two
aren't the same). Just becuase I have a 1200x900 image scaled in a
4x3" box doesn't mean my printer will use 300DPI when it prints -
I've
seen cases where printers/programs actually take a 72DPI image and
upsample it to 300, then rescale it to the desired size on the page,
which doesn't look too good in print. Anyway, I've started using the
GIMP to reset my print size without affecting the image in any way,
so
its easy to just drop the image into whatever program without having
to do too much math (desired image size * 300 / 72 = head 'asplode).
I've attached a GIMP non-interactive script, if anyone finds it as
useful as I do. After running images through povray, I run:
gimp -i -b '(batch-printsize-change "*.png" 300.0 300.0)' '(gimp-quit
0)'
I'm sure photoshop can do the same, but I've never really used it...
HTH,
Tim
---------------------------------------------------------------------
---
(define (batch-printsize-change pattern
xresolution
yresolution)
(let* ((filelist (cadr (file-glob pattern 1))))
(while filelist
(let* ((filename (car filelist))
(image (car (gimp-file-load RUN-NONINTERACTIVE
filename filename)))
(drawable (car (gimp-image-get-active-layer
image))))
(gimp-image-set-resolution
image xresolution yresolution)
(set! drawable (car (gimp-image-get-active-layer image)))
(gimp-file-save RUN-NONINTERACTIVE
image drawable filename filename)
(gimp-image-delete image))
(set! filelist (cdr filelist)))))
