How do i Resize A Cirlce and Square for drink coasters

[nicholascopey]

Hi iam currently starting a little businees doing drink coasters, the coasters take 9 centimeter photos , 
can anybody help me and explain how i resize a image ready for print . 
iam new to gimp if anybody can help me out step by step then i will send them a free gift.please help me out

thx
nick

the size of the drinks coastes
SQUARE 90MM x 90MM
CIRCULAR 90MM

[Blighty]

Two things to note:

1. Gimp uses sizes in pixels, not real world sizes like mm.

2. A 90mm circular image is actually a square 90x90mm. The portions outside of the circle are transparent.

Both your square and circle will be the same size, 90x90mm.

For a good quality print you need 300 dpi, or 11.81 pixels per mm.
90 x 11.81 = 1063pixels. ie an image 1063 x 1063 pixels.

Gimp can do these calculations for you. Go to File>New and set the width and height to 90mm. In the advanced section set the resolution to 300 dpi. You will see on that screen that the image size has been set to 1063 pixels.

[rich2005]

Are these going to a commercial printer (aka printer) for printing?

If so, then look at their requirements. One might be a "bleed area" making the image more than "90 mm" Ask if they have a template, many printers have these.

Generally, Gimp works in pixels not millimetres, so the 90 mm has to be converted to pixels at a print resolution.

Make a new canvas like this using 300 ppi as the print resolution. https://i.imgur.com/tXrttnC.jpg

Add a transparent layer on top and make a circle to define a circular coaster. An example gimp xcfgz file attached to play with.

Any photgraph is liable to be too large (sometimes too small, never correct first time)

Copy it, paste it, resize it, move it while still a floating pasted layer: https://i.imgur.com/OQnewsa.jpg

Then it is a matter of anchoring the image, tidy up any unwanted bits. https://i.imgur.com/YWtMllr.jpg

You can use a selection to crop to a circle, not usually required for a printer, they take care of that. Turn off the visibility of the template layer before exporting as a (whatever the printer wants)  https://i.imgur.com/K9zOry9.jpg

[nicholascopey]

Wow Thankyou for your help ,What a great site this is Thankyou to both of you .