You can upload images for product part option values by naming the image file according to the option value's code, such as "format_14_8x21.png" for the A5 format with the code "format_14_8x21".
Here you can upload images that are to be used for the individual product part option values.
Note that the image name corresponds to the code of its value.
Example:
Let's assume we want to change the image of the format (A5) framed in blue:
In this example, the format has the code: format_14_8x21. So now we should name the image “format_14_8x21.png”.