GraphPad supports several graphics formats for export purposes (including JPEG), so you can export your projects (.pzf) and save parts of them as .jpg files. It doesn't seem any other program supports .pzf projects, so this is your only choice.
Convert GraphPad Prism project to JPEG bitmap image format.
We found one software available in the database for this conversion.
Microsoft Windows software - convert pzf to jpg on Windows
A biostatistic scientific program with graphing capabilities
Convert from pzf file format
The table with program actions contains information about what each program is capable of doing with their files. This may be a good pointer for further searches for certain file conversions and help you find the converter you are looking for if our search result is insufficient for you. However, it is far from perfect and may sometimes show results which are not really usable because of the nature of the software handles the files. So a conversion that appears as possible, just because of matched actions, may in fact not be possible.