Simg2img (Sparse Image to Image) is a command-line utility designed specifically to convert into raw images . Manufacturers use sparse images to save bandwidth and storage space. While a raw image contains every single byte of a partition (including empty zeros), a sparse image compresses those empty blocks.
The same sources that provide simg2img.exe also include img2simg.exe. Simg2img.exe Download
Create a batch script ( convert_all.bat ): Simg2img (Sparse Image to Image) is a command-line