Dividing and printing a large image

[RayArdia]

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I am using Gimp 2.8 on an Ubuntu 16.04(linux) OS. I'm fairly familiar with Gimp, although my efforts, especially in the subject area, tend to be a bit 'hit and miss'.

I make mosaics and have need from time to time to re-size fairly small images (usually symbols of one kind or another) and to print at perhaps 400x400mm. Whilst I can tolerate the slightly fuzzy (even using Sinc (Lanczos3)), I really do need to find a way of dividing a large image into smaller, print-sized parts.
I had thought that slice-and-join.scm would do but cannot get it to work. One comment from a Ubuntu forum member was:-

"Actually just very buggy code. It append the Gimp data directory to any directory your give in the parameter dialog. So, when asked to use /tmp, it tries to open /tmp\home/me/Sandbox/Image.jpg.rcm. The file open fails, this isn't checked, and the ensuing write fails (the write:argument 2 must be: output port message, because it tries to write to #f (false))... In addition all the directory names processing uses hard-coded backslashes, so that's a Windows-only script."

Perhaps there's some truth in the above and that my trying to use it within a Linux OS was the main error; the fact is that I wasn't able to use that, so I need to find something else that will do the job - I'm hoping someone can help point me in the right direction.
Ray

[Blighty]

Have you tried the guillotine?
Image > Transform > Guillotine

Create guides where you want to divide the image. For example, use guides to create a 4x2 grid over the image. Now use the guillotine. The image is cut on the guidelines and a new image created for each piece.

[rich2005]

Quote:...Whilst I can tolerate the slightly fuzzy (even using Sinc (Lanczos3)), I really do need to find a way of dividing a large image into smaller, print-sized parts.

Blighty's recommendation + a couple more.

These are all ones I have installed in my (K)ubuntu 16.04

You can set up a Grid-of-Guides with a script. The script attached guides-grid.scm sets them up either by number of divisions or by pixels. Find it in  Image -> Guides -> Grid

The stock guillotine works, but cuts the image up into separate images. That is ok for four or six tiles. More than that and it becomes tedious to save/export each image.

Guillotine-into-layers-64 is a compiled plugin that does the same except assembles the tiles into layers in a single image. Next to the regular guillotine in Image -> Transform. Being a single image, it is possible to scale all the tiles in one go.

Want all those layers exported easily into images? Anitools.py one of the options is exporting layers in the form 001.png ...002.png... Tools -> Anitools -> Export all layers.

Unzip, plugins go in ~/.gimp-2.8/plug-ins (they should already be marked as executable but check) the script in ~/.gimp-2.8/scripts

[Ofnuts]

(08-09-2017, 12:16 PM)RayArdia Wrote: One comment from a Ubuntu forum member was:-

Yeah, one really wonders who that guy is

[Ofnuts]

Must be Christmas, see https://www.gimp-forum.net/Thread-ofn-tiles

[RayArdia]

(08-09-2017, 02:16 PM)rich2005 Wrote:

Quote:...Whilst I can tolerate the slightly fuzzy (even using Sinc (Lanczos3)), I really do need to find a way of dividing a large image into smaller, print-sized parts.

Blighty's recommendation + a couple more.

These are all ones I have installed in my (K)ubuntu 16.04

You can set up a Grid-of-Guides with a script. The script attached guides-grid.scm sets them up either by number of divisions or by pixels. Find it in  Image -> Guides -> Grid

The stock guillotine works, but cuts the image up into separate images. That is ok for four or six tiles. More than that and it becomes tedious to save/export each image.

Guillotine-into-layers-64 is a compiled plugin that does the same except assembles the tiles into layers in a single image. Next to the regular guillotine in Image -> Transform. Being a single image, it is possible to scale all the tiles in one go.

Want all those layers exported easily into images? Anitools.py one of the options is exporting layers in the form 001.png ...002.png... Tools -> Anitools -> Export all layers.

Unzip, plugins go in ~/.gimp-2.8/plug-ins (they should already be marked as executable but check) the script in ~/.gimp-2.8/scripts

Many thanks to Blighty and yourself for your helpful pointers. Have to admit that I didn't even know of guillotine's existence in Image-Transform - I do now! All other tips noted.
The old saying "You learn something new every day" is still true when you're old - trouble is you forget it again the day after.
Regards, Ray

[RayArdia]

'You can set up a Grid-of-Guides with a script. The script attached guides-grid.scm sets them up either by number of divisions or by pixels. Find it in Image -> Guides -> Grid'

I've found this to be the most workable solution, mainly because the slice-and-join.scm script doesn't work- I get the selection screen OK but then get an error 'Error while executing script-fu-image-slice: Error<unknown>:151148360) write: argument 2 must be: output port'
I would like at least to be able to try slice-and-join but can cope with Image -> Guides -> Grid, BUT I would like to have the guides appear on the final prints so that I can cut and stick them all together to make my mosaic patterns. How can I keep the guides on the print please?
Sorry for the dumb questions but do appreciate your help.
Ray

[Ofnuts]

To replace slice-and-join (at least the "slice" part) see here

Guides are only a visual indication, they are not part of the image. if you want to see them in print you have to create a path over them and stoke the path. But then since they extend beyond your image part you are no longer making just sub-images, but adding a frame around such images and this is quite different problem.