If you look closely , it has white borders all over (see here). Now my question is , is there any software (free) that can help me crop out the circular area of the button.
I have: Windows 7 with GIMP (though I can't find such feature in GIMP) and Paint (same again)
You could use Paint.Net.
Open your image or copy it into a new image.
Pick the ellipse selection tool.
Place the cursor on the edge of the circle in the image:
Press and hold Shift and Alt and drag the cursor to the opposite side of the circle.
Depending on what you want to do, you might actually want to select everything but the circle. For that you can use the Invert selection.
To use it, first select everything by pressing Ctrl+A and then performing the selection process as described above, in the Invert selection mode. Then you'll have everything but the circle selected.
If you then press Del, you end up with a clean button image:
I prefer the magic wand - the trick being to lower the tolerance as low as possible to get a good result - I've used 10% but you can go as low as 1
Well, you certainly can do it on GIMP. There's an ellipse tool as well:
It's very similar in selecting to paint.net, but you can also change the area of the selection after selecting it the first time --maybe to make fine adjustments-- by clicking and dragging your mouse over the squares appearing when you hover your mouse over the vertices or rectangles when it's over the edges of the square guide:
And zoom in if necessary:
After that, you can hit Ctrl+I (Invert selection or do "Select" > "Invert Selection" from the menubar to select everything outside the ellipse, then press Delete to remove the unneeded part:
The checked grey pattern indicates that these parts are transparent. If you don't see this, go to "Layer" > "Transparency" > "Add Alpha Channel" and press delete again without deselecting the current selection.
Now your image is ready to be exported as png :)
