Which is the best free software to reduce size of jpeg photos without much change in quality?
It’s not the program you use which makes the difference but the amount you want to reduce by. It’s not possible to reduce a jpeg by that much without a noticeable loss of quality. Jpeg compression reduces file size by reducing the number of pixels in an image. It does this by averaging colors. For example four adjacent pixels of slightly different hue are averaged and the result is one pixel. In this example a 400 Kb file would be reduced to 100 Kb but the dimensions of the resulting graphic will be much smaller. The graphic will still look sharp to the human eye until it is enlarged. The more the file size is reduced the greater the loss of quality. It is a by-product of the method and cannot be avoided. PIXresizer is a free app which can reduce file size.