The first thing to understand is that Gimp (and all bitmap editors) work in pixels, not inches. Only whole pixels, there cannot be fractions of a pixel. If you specify a size in inches the resolution you specified (dpi) is used to calculate the size in pixels. This is rounded to nearest whole pixel size. This creates a small variation in the inch size that you initially specified.
OK, I think this is what you mean:
2.6875 - (2 x 0.39) = 1.9075
3.21875 - (2 x 0.39) = 2.43875
I created a new image size 2.6875" x 3.21875", 300dpi.
I then created a rectangular selection as per the image below.
Click inside the selection to finalize.
Bucket fill with colour you require.
Note: you will still get small variations in inch sizes when rounding to the nearest whole pixel takes place.
Quote:a border that is 39" thick or 2.2975" x 2.82875"I don't understand this part.
OK, I think this is what you mean:
2.6875 - (2 x 0.39) = 1.9075
3.21875 - (2 x 0.39) = 2.43875
I created a new image size 2.6875" x 3.21875", 300dpi.
I then created a rectangular selection as per the image below.
Click inside the selection to finalize.
Bucket fill with colour you require.
Note: you will still get small variations in inch sizes when rounding to the nearest whole pixel takes place.