What is jpgQ - JPEG Quality Estimator? Why do I need it?

jpgQ is a JPG/JPEG Quality Estimator and free to use. jpgQ allows to load a JPEG picture and estimate the quality the picture was last saved.

Knowing the JPG/JPEG quality of a picture helps to you to decide what quality to use when you want to save the picture again after you made some minor changes.

As a general rule, you should save a JPG/JPEG picture with the same compression quality level as the last time when the picture was saved.

If you save a JPG/JPEG picture with quality level lower than last time, You are decreasing the quality of the saved picture. But the file size is reduced.

If you save a JPG/JPEG picture with quality level higher than last time, You are wasting storage becuase the file size is increased. And there is no improvement on picture quality because JPG/JPEG compression can not recover what was lost during the last compression process which used a lower quality level.