Those of you that have the money to buy the full version of PhotoShop for Mac, great, for those of you that don’t there are a few cheaper options but why not go with something that’s completely free.
There is the GIMP (GNU Image Manipulation Program) but I didn’t like it on OSX and it’s also terribly ugly on Windows. SeaShore is based loosely on the GIMP but from where I stand, runs and looks better on OSX, almost like a native app.
SeaShore is not a replacement for a professional image editing program and it does not provide all the features that the GIMP would, it does basic image editing needs, resizing, cropping, basic layer support and a few effects but that’s about it.
During my time with Mac OSX, I liked SeaShore and it met most (but not all) of my image editing needs. Other than SeaShore and the GIMP there are not that many freeware choices for Mac image editing, suffice it to say, there are a greater number available for Windows.
Of course, if you don’t need the power of the full version of PhotoShop, there is always PhotoShop Elements that can be had for about $80 on Windows and Mac.