Bad quality of picture on Crystal Report?

We are using Crystal Report .Net to create our reports.
We have inserted a picture on the Crystal Report,
but when we export the report to a pdf-file
to print the report, the quallity of our picture is very bad.
We have already tried with jpg,with other resolutions,with an ole object but
that doesn't resolve our problem.
How can we put a picture on our crystal report, without losing quality when
exporting to pdf?

Thank you very much for any answer,
Sandra Lambrechts