How to change the alpha value to blue/vise versa in Paint.NET Discussion and Questions Posted August 19, 2013 · Report reply 1. Open the image in Paint.NET and Zoom In to 200% or more. 2. Select the Color Picker tool and click anywhere on the blue colour. 3. [Menu] Adjustments > Brightness and Contrast and set Brightness -100 and Contrast 100. This will turn the blue background to black. 4. Select the Paint Bucket tool and click anywhere inside the transparent "f". 5. Select the Magic Wand tool and click anywhere on the black background. Hit "Delete" on your keyboard. 6. Select the Eraser tool to clean up the edges of the image. And the result is a pixelated image, I could do it so, but I want to have the alpha values so it looks more like "f" from a font, not a video game.