Sample Images with best possible JPG-Quality
From the two sample images on the right the two highlighted snippets are used in the following to visualize the possible loss of quality.
It is one image with large relatively unstructured areas and one with a lot of details so the compression will work differently. Both have an original resolution of 10 megapixels.
We start with the snippets in best possible quality – created from RAW data, stored without any loss in quality (the simplest bmp format). You see them in 100% size, i.e. one pixel of the image file = one pixel on your monitor.
Please note: The complete image would be (depending on your monitor) about one meter wide – way bigger than you normally zoom into a picture.
Move the mouse pointer over the images to see them as a JPG file of best possible quality.
As you can see, you see nothing.
First conclusion: In JPG images of best possible quality the possible loss in quality is not relevant.
There can indeed be losses of quality but they depend on how much the data is compressed and this can be defined when a JPG file is created.
Each reasonable image processing software and many digital cameras have a settings for this.
In the sample images shown here the file size has already gone down to less than half and about one third of the uncompressed data.