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This guide will show you how to apply a gradient from within photoshop by creating an additional layer, All you have todo is rotate your image 90% before you start as Grdients are applied left to right http://www1.appstate.edu/~bodorw/InDesignPhoto%20ShopTips/How%20to%20Create%20a%20Transparent%20Gradient%20in%20Photoshop.pdf
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