GIMP

[azar]

HELLO I will try to explain my problem. I want to turn an image into a poster with custom dimensions, so I wanted to use GIMP’s guides and crop the image following the guides. The thing I don’t understand is that nothing matches when I put them in the image: the image size, the guides, etc.

I have an image that is 63×83 cm.

I set my margins in cm based on the image scale, but they should be much smaller. Instead, they are still set to 1 cm.

And when I go to Image > Image Size and Dimensions, I get another size entirely.

THANK

IMAGE

[Ofnuts]

Start here: https://www.gimp-forum.net/Thread-Image-size-in-Gimp

Also, don't confuse the Rectangle select  () and the Crop tool ( )

[azar]

thank but I looked at the information from the link, but it's too complicated for me
What I wanted to do was a poster like Posteriza, an image split across multiple sheets. I wanted to try it with GIMP like this.

Manual Method with GIMP

If you prefer to do everything in GIMP:

   Open your image.
   Resize it to the desired total size (Image > Scale Image).
   Create guides to divide the image:
       Go to Image > Guides > New Guide (by percent).
       Add vertical and horizontal guides to split the image into multiple parts.
   Cut the image into sections:
       Select an area using the rectangular selection tool (following the guides).
       Copy and paste into a new image (Ctrl + Shift + V), then save as PDF or PNG.
   Print each section separately and assemble the sheets.


It's just that with the guides, I can't set it to A4 format (210 × 297 mm)

merci

[Ofnuts]

(3 hours ago)azar Wrote: thank but I looked at the information from the link, but it's too complicated for me
What I wanted to do was a poster like Posteriza, an image split across multiple sheets. I wanted to try it with GIMP like this.

Manual Method with GIMP

If you prefer to do everything in GIMP:

   Open your image.
   Resize it to the desired total size (Image > Scale Image).
   Create guides to divide the image:
       Go to Image > Guides > New Guide (by percent).
       Add vertical and horizontal guides to split the image into multiple parts.
   Cut the image into sections:
       Select an area using the rectangular selection tool (following the guides).
       Copy and paste into a new image (Ctrl + Shift + V), then save as PDF or PNG.
   Print each section separately and assemble the sheets.


It's just that with the guides, I can't set it to A4 format (210 × 297 mm)

merci

When you  copy-paste to a new image, you copy-paste pixels not centimeters. What size the pixels have in the target image depends on that image print definition. It could be better to do Image > Duplicate (so that you copy pixels and print definition together) , and crop that duplicate to the part your want to print.

Technically you cannot print a full A4 size on A4 paper. Printers have margins (on inkjets this is often about 1cm at the bottom) and usually by default the print driver with scale/shrink the image to fit the printable area.

If you want a seamless result, you use the technique used for wallpaper strips:

1. You create all image parts with a decent overlap between parts (around 2cm on each side where there will be an adjoining panel)
   
2. You do a rough cut of the printed sheets to remove any margin, slightly inside (so you start eating a bit in the 2cm of overlap)
   
3. You position two adjoining panels, with one overlapping the other, for a seamless result
   
4. You make a cut through the two layers across the middle of the overlap area (this cut doesn't need to be straight nor accurate, as long as it is always across the two layers
   
5. You remove the overlap strips that have been cut out (top and bottom sheet)
   
6. The two remaining sides should join seamlessly.
   

[rich2005]

Gimp works in pixels, and that information is hidden in your screenshot by the window icons. That will determine the final quality.

(1) There is a script-fu that will place a guide using "real-world" units. Only one guide at a time, use multiples of 21 cm and 29.7 and build up the grid for Image -> Slice using Guides. The script shows in the Image -> Guides -> New Guide (by unit)
(attached, unzip and put in your scripts folder)

(2) Another option is the Rectangular Selection tool with the aspect ratio set to 1:1.414 Make selection then Image -> Guides -> New Guides from Selection. Move the selection around and build up the grid of guides.

   

[azar]

merci
Thank you for all this information