Why do you need to look for others when you’ve already had free, capable application shipped along with your Leopard?
As Usual, Find Image First
Some of the readers might have known that I like to find an image before starting my tutorial. Here is the chosen one :
After highlighting it, open it with Preview, in short : Preview It.
Tips : I usually open file by dragging it to application’s icon on the Dock. It’s way easier than using navigation provided by the application itself.
Choose the Tool : Adjust Size
Select Apple ▸ Tools ▸ Adjust Size…
Don’t be shocked if pane like this pop-out suddenly. It’s usual.
Now you can resize the image by putting some width/height value. You can also choose to scale it proportionally or not. Not only that, as standard image resize tools, you will find many variation of measurements, such as inches, pixels, percentages, etc (you name it).
Tips : If you want to resize your image into standard size, you can consider using the Fit Into option bar. Those standard sizes are already defined there.