- (values (* 1000 (/ (car imager-dim) (car pixel-dim)))
- (* 1000 (/ (cdr imager-dim) (cdr pixel-dim))))))
+ (when (and pixel-dim imager-dim)
+ (values (* 1000 (/ (car imager-dim) (car pixel-dim)))
+ (* 1000 (/ (cdr imager-dim) (cdr pixel-dim)))))))
+