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Frustration with The GIMP - Drinking from the Fire Hose — LiveJournal
and trying not to drown

Date: 2004-04-16 14:42
Subject: Frustration with The GIMP
Security: Public
That's the GNU Image Manipulation Program, not the noun meaning (1) A limp or a limping gait or (2) A person who limps.

I'm working on a project that requires teeny tiny little pictures. As in 5mm x 7mm. The pictures will be printed by a photo lab, so printer resolution is not what's causing me so much grief.

My first problem is that I simply don't understand why pictures are one size on the screen yet print as something entirely different. And how can it be that two images the computer tells me are 4x6 (inches) are completely different sizes when displayed side-by-side on the screen - when both are supposedly being displayed at at 100%?

The second and even more aggravating problem has to do with image reduction. I have not been able to figure out how to make the images as small as I need without having them become blurry. I know it's theoretically possible, because two of the images I'm working with were reduced by someone else and the prints they gave me are perfectly clear and crisp. (Before anyone asks, no I can't ask that person how she did it. I want to know so that I can stop paying her to do it for me - and,if it turns out I enjoy the work, I may end up going into the business myself and would become one of her competitors.)

I've looked at the help files, I've read both the books I bought on GIMP, I've even been to the library in the hope that a more general discussion of digital photography would help. And I've tried playing with the images. For days. Thus far, all I've managed to do is produce images that are clear when large and blurry when they're the size I need.

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Instigator of Inappropriate Imagery
User: kevinnickerson
Date: 2004-04-18 20:43 (UTC)
Subject: (no subject)
An image has a pixel dimension, and a printable dpi. The dpi is simply stored as one number in the image. It's possible to change just that two (four?) bytes and not touch the rest of the bytes in the file. The problem is that almost all image viewers will ignore the specified dpi and simply display at monitor resolution, so it's generally meaningless. When you do print it though, it's important.

As to your blurry images, you're probably just reducing the number of pixels. You need to keep the pixel count high, but reduce the print size. I was going to look up the correct syntax for <a href="http://www.imagemagick.org/>ImageMagick</a>, but they've went from version 5.5 to 6.0 and completely revamped the command line and I'm confused. The relevant options are resize and density. For a 5mmx7mm you probably want 236x331 pixels with a dpi of 1200. If the resizing makes it blurry, just mark it as 2400 dpi and double everything. For the 1200 dpi case, I suspect the correct command line will be "convert input.jpg -resize 236x331 -density 1200x1200 output.jpg"
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