You have multiple options:
Mendix only
Images can be used in document templates. So create a document template with this image and create a pdf from this document template.
Using Java
See for instance https://roytuts.com/convert-image-to-pdf-file-using-java/
Using an API
https://www.convertapi.com/jpg-to-pdf
If you shed your use case a bit more we can think along with you.
Regards,
Ronald