Currently Being ModeratedOct 30, 2012 3:34 AM (in response to Chadfrombc)
Keynote is a presentation application and is designed for that purpose, therefore the pixel dimentions available in Keynoteare are proportional to that supported by the graphics card in the computer.
Keynote wont go smaller than 200 px and 4000 px
If you need this flexibility you will need to use a graphics editing application; Photoshop - Paintshop, even the freeware apps like Paintbrush.
Currently Being ModeratedNov 4, 2012 10:40 AM (in response to Chadfrombc)
In the situations where I needed a size Keynote didn't support, I've created at some multiple that Keynote DOES support then use Preview to render it at the final size I wanted.
For example, have Keynote export 1456x180, Open that in Preview, Show the Edit Toolbar (Shift-Command-A), then choose the Adjust Size icon on the right and put in 728x90. Export that as the file type you need and there you go.