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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? 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))))) >> > >
