Select each of your two images in turn and go command a (Select All) and command c (Copy) Double click on this along with your two existing images to open them in Preview. Make a screensnap: command shift 4 > drag out an area 640 x428 Not strictly necessary but makes life easier. Open up any Application that lets you have a clean neat whiteīackground.How to do this with the tools to hand: Preview. I used it on and now the correct code is convert +append a.png b.jpg +append c.tif Alternatively, you could put this in some sort of automator script. This isn't a GUI application, but maybe some others might have a better solution. For example, you can switch to a different image format for the output convert +append a.png b.jpg c.tif With convert, you can do a ton of other things. Alternatively, you append them vertically with -append (instead of +) and a.png will be on top of b.png. To create a new file, c.png, that has the a.png on the left and b.png on the right.
If you have your two 320x428 images, say a.png and b.png, you can do convert +append a.png b.png c.png
The actual tool you want to use from Imagemagick is the convert tool. You could also choose to install with brew ( brew install imagemagick). I use the command line tools that come in the Imagemagick package I think I installed it on my system with MacPorts.
I often have to do this with images of plots of data.
