03-17-2018, 04:40 PM
The important thing to know is that Gimp (and all bitmap editors) work in pixels and not in units such as inches or ppi.
If you require an image 18"x24" 300 ppi then you need an image size of
(18x300)x(24x300)
=5400x7200 pixels
When you add additional graphics look at the size of these graphics in pixels. Other units are irrelevant. Compare the size of these graphics to your image size of 5400x7200 pixels
You will probably need to scale these graphics to the required size. But remember when scaling bitmaps there is always a loss in quality. If you scale down pixels are thrown away. If you scale up some algorithm creates new pixels. The more you scale the greater the loss in quality.
If you require an image 18"x24" 300 ppi then you need an image size of
(18x300)x(24x300)
=5400x7200 pixels
When you add additional graphics look at the size of these graphics in pixels. Other units are irrelevant. Compare the size of these graphics to your image size of 5400x7200 pixels
You will probably need to scale these graphics to the required size. But remember when scaling bitmaps there is always a loss in quality. If you scale down pixels are thrown away. If you scale up some algorithm creates new pixels. The more you scale the greater the loss in quality.