I have an image (png, size 4288x2848) that I want to fit in a landscape a5 pdf with a 1cm border.
I know I can do it with
ImageMagick but don't know how.
A5 landscape size is
1cm border (i.e.
10mm) that means the image should be
200mm wide and
138mm high hence an aspect ratio of
1.45 - and your original image (
4288x2848) is slightly wider:
1.51 aspect ratio. You'll have to crop it first to
4130x2848 so as to have the same aspect ratio.
You could do that by simply using
convert in.png -extent 4130x2848 out.png
will crop the image to the desired size leaving the top left corner unaffected
or you could instead crop relative to gravity e.g. center:
convert in.png -gravity center -crop 4130x2848+0+0 +repage out.png
whichever suits you better...
Once you have the cropped image you can convert it to
A5 e.g. @
300px per inch (which is equivalent to
118px per cm) the size of the canvas is
2480x1748 however if you subtract the
10mm border which is
118px your image should be
2362x1630 and the remaining is the white background so again, with the help of
convert out.png -resize 2362x1630 -background white -gravity center -extent 2480x1748 out.pdf