I have three photos, a.png, b.png and c.png, I need to combine them into two rows (top and down) so that a.png be in the top center of b.png and c.png i.e. it looks like
a.png
b.png c.png
I used this command
convert \( a.png \) \( b.png c.png +append \) -append combine.png
but this command doesn't center a.png in the middle of first raw instead the combined photo looks like
a.png
b.png c.png