Basic photo editing on OS X I need to edit a photo on my Mac. I wish to take two photos and paste them together to create one that's larger, containing both. I couldn't figure out how to do this with iPhoto.


For Windows you have Paint.NET.   
For Linux you have Kolourpaint.


What would be the equivalent on OS X?

Please note that it must be of quality both in code and in UI. I wouldn't want to install buggyware on my Mac.
You can do this simply with Preview. Open the first picture. 


Choose Tools > Rectangular Selection.
Select the whole picture.
Copy the selection (choose Edit > Copy).
Choose Tools > Adjust Size.
Turn off the lock for proportional changes.
Select pixels as your unit.
Double the width of your picture.


At this point, you have your unscaled picture in the clipboard and a scaled version in Preview.


Insert (choose Edit > Paste) the picture from the clipboard and align it to the left edge.
Open your second picture in Preview, select everything, and copy it.
Switch to the first picture, paste the second picture and align it to the right edge.
Save your new picture. Done.