Change the file size or quality level of a JPEG picture
Most of the pictures on your computer are probably saved in the JPEG format, since this is the preferred format of most digital cameras. JPEG pictures have the advantage of retaining high visual quality and having a relatively small file size. This is because the JPEG format compresses information in the picture to reduce the file size without affecting the picture's resolution.
If you want to make a picture's file size smaller to save storage space, you can reduce the file size of one or more pictures by using a photo editing program to reduce the quality level of the picture. This technique reduces the file size without reducing the actual number of pixels in the picture.
For the best visual quality, you should save your JPEG pictures with a high quality setting (which is the same as a low compression level). This happens automatically when you save pictures using Windows Photo Gallery or Paint.
If you want to reduce the file size of a picture to send in e‑mail, see Send pictures or videos in e‑mail.