I did it a certain order but I'm not sure that matters exactly.
When I did the resize, I just typed in 1680 in the width box and it automatically worked out the height. If you're cutting your banner out of a wider picture you might want to start with the width crop first, just getting the part you want but making sure it's not smaller than 1680x153.
Then resize the picture to 1680 width and it should do a plain scale with the same aspect.
Then a crop to height 153 px. Move the crop selection to the spot you want.
I did it a certain order but I'm not sure that matters exactly.
When I did the resize, I just typed in 1680 in the width box and it automatically worked out the height. If you're cutting your banner out of a wider picture you might want to start with the width crop first, just getting the part you want but making sure it's not smaller than 1680x153.
Then resize the picture to 1680 width and it should do a plain scale with the same aspect.
Then a crop to height 153 px. Move the crop selection to the spot you want.