RIOT is one of my favorites as you can check preview of compressed image in real time. My Favorite Free Portable Image Compressor Software for Windows: All in all, these are great image compression software that come in portable packages. A few software also provide you a feature to compress image by a specific size. For example, a Batch feature is available in most of these software that lets you compress multiple images at once. You can find a lot of additional handy tools in these image compressors. Many of these software allow you check out the preview of compressed output image and compare it with the original image. You can achieve desired compressed size of output image by adjusting various compression settings like quality, color reduction, color quantization, compression level, etc. Although, some of these are used only for specific image formats, most commonly PNG and JPEG. These image compressors let you compress images of multiple formats including JPG, PNG, BMP, GIF, TIFF, TGA, ICO, etc. You can also carry these software in USB drive or any other portable storage device and use them whenever required. These software work without installation and let you compress images on the go. Using these software, you can reduce size of images as per your requirement. Here is a list of Best Free Portable Image Compressor Software for Windows.

Realtime image compression software