How can I filter images by orientation in Finder to show only portrait/vertical images or only landscape/horizontal images?
Search for images by pressing Command + F
Add a search attribute
Pick the "Orientation" attribute
Set "equals" to
0 if you want landscape/horizontal,
1 if you want portrait/vertical
On OS X El Capitan, to bring up the search screen I use the key combination Command F, instead of CTRL F.