|Free jpeg compression software is available here.
Help Page: Free jpeg Optimiser for Windows
Load a file in jpeg Optimiser. The example file is a png, with a size on disc 327K. Click the Compression drop down and try out some values (nothing changes on your computer.
I got down to 5% and saw:
The image on the right has blemishes and is unacceptable, at 5% and 30K on disc.
The image below has 15% compression and seems acceptable for the web. There are some blemishes. This is a demonstration. Many times there is no need to go to the limits, just make the size on disc a bit acceptable.
Up till now nothing has changed on your computer. If the image is acceptable, then save it to your computer.
Always save your images as a new file, and don't over-write your original image. To encourage this, the program does not have a save button: just a save as button. I suggest you to save images as new files and don't overwrite the original.
The Options menu is the same as that for Image Viewer. See: Image Viewer Options Menu. You set it up the same way.