Googled and found this but haven't tried it:
Crystal Reports XI and later
If you have CR XI or above, the following steps will display a dynamic image when the database stores a reference to a separate image file:
Use Insert Picture to insert a static image into the report, as described above. Select any image file. Drop it in the report at the point where you want the final image to appear.
Right-click on the image, choose Format Graphic, and go to the Picture tab. Click the conditional formatting button (the ""X-2"" button) adjacent to Graphic Location label.
You are now in the formula editor. Create a formula that returns the filename or URL of the image you want to display (typically, the formula will simply return the contents of the field in the database that holds the filename or URL).
Come out of the formula editor. Refresh the report. You should now see all the images at the appropriate points in the report.
Unfortunately, this technique won't work in earlier versions of the CR. Versions before XI don't offer a direct way of showing a picture when the database only contains the filename or URL.