RenderDoc is a free MIT licensed stand-alone graphics debugger that allows quick and easy single-frame capture and detailed introspection of any application using Vulkan, D3D11, OpenGL & OpenGL ES or D3D12 across Windows 7 - 10, Linux, or Android.
As described by Lifehacker.com: "Mangle is a handy tool for formatting your Manga and comic collections for easy reading on your Kindle. It includes page sorting, downsampling, and auto rotation for fuss-free reading."