Convert picture to 3 different sizes for icon for iitunes app store

I need the attached picture in 3 formats for apple store. So 3 pics in total 1) large version of your app icon that will be used on the App Store. It must be at least 72 DPI, in the RGB color space, and 1024 x 1024 pixels (it cannot be scaled up). The file type must be .jpeg, .jpg, .tif, .tiff, or .png. It must be flat artwork without rounded corners. I also want the following 2) iPhone 5 and iPod touch (5th gen) Screenshots must be .jpeg, .jpg, .tif, .tiff, or .png file that is 1136x640, 1136x600, 640x1136 or 640x1096 pixels, at least 72 DPI, and in the RGB color space. 3) iPad Screenshots must be .jpeg, .jpg, .tif, .tiff, or .png file that is 1024x768, 1024x748, 768x1024, 768x1004, 2048x1536, 2048x1496, 1536x2048 or 1536x2008 pixels, at least 72 DPI, and in the RGB color space.