Resizing gif images

I have a gif image 720 * 40 pixels 开发者_开发百科used as a footer on a website. I need to extend the height of the gif by 10 pixels. I was unable to resize to this, using Office Picture Manager. What is the best way to achieve this?

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Use an image editor such a photoshop or gimp or paint.net.

Create a new image sized 730 * 40 and paste your original to it.

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You could also try an online solution like this