A system for assessing the acceptability of product filter rods, filters or filter elements which comprise a longitudinally extending core of filtering material including a longitudinal channel extending from an end of the core; the system comprising: (a) means for advancing a flow of product filter rods, filters or filter elements such that each filter rod/filter/element in the flow is oriented with the end (of the filter rod, filter or filter element) from which the longitudinal channel extends exposed; (b) means for capturing an image of an exposed end of a filter rod, filter or filter element in the advancing flow; characterized in that the system further comprises: (c) means for comparing the captured image with an image of a standard rod, filter or filter element; and (d) means which determines, from the differences between the captured image and the image of the standard rod, filter or filter element, a value for one or more of: (i) the cross sectional area of the longitudinal channel at the exposed end (of the filter rod, filter or filter element); (ii) the amount of material detectable within the of the longitudinal channel at the exposed end; (iii) the outer perimeter of the longitudinal channel at the exposed end; (iv) the position of the longitudinal channel in the exposed end; (v) the outer perimeter of the core; (vi) the amount of material detectable outside the outer perimeter of the core at the exposed end; (vii) the amount of impurity visible in the filtering material at the exposed end; (viii) the shape of the cross section of the longitudinal channel at the exposed end; (ix) the area of the exposed end having a specific colour or pigment; (x) the diameter of the exposed end; and (xi) the diameter of the longitudinal channel in the exposed end; and compares the (or each) determined value with a predetermined value to thereby assess whether the filter rod, filter or filter element is acceptable; wherein the value(s) is determined based on portions of the captured image which are different when the captured image is compared to the image of the standard rod, filter or filter element. (a) means for advancing a flow of product filter rods, filters or filter elements such that each filter rod/filter/element in the flow is oriented with the end (of the filter rod, filter or filter element) from which the longitudinal channel extends exposed; (b) means for capturing an image of an exposed end of a filter rod, filter or filter element in the advancing flow; (c) means for comparing the captured image with an image of a standard rod, filter or filter element; and (d) means which determines, from the differences between the captured image and the image of the standard rod, filter or filter element, a value for one or more of: (i) the cross sectional area of the longitudinal channel at the exposed end (of the filter rod, filter or filter element); (ii) the amount of material detectable within the of the longitudinal channel at the exposed end; (iii) the outer perimeter of the longitudinal channel at the exposed end; (iv) the position of the longitudinal channel in the exposed end; (v) the outer perimeter of the core; (vi) the amount of material detectable outside the outer perimeter of the core at the exposed end; (vii) the amount of impurity visible in the filtering material at the exposed end; (viii) the shape of the cross section of the longitudinal channel at the exposed end; (ix) the area of the exposed end having a specific colour or pigment; (x) the diameter of the exposed end; and (xi) the diameter of the longitudinal channel in the exposed end; (i) the cross sectional area of the longitudinal channel at the exposed end (of the filter rod, filter or filter element); (ii) the amount of material detectable within the of the longitudinal channel at the exposed end; (iii) the outer perimeter of the longitudinal channel at the exposed end; (iv) the position of the longitudinal channel in the exposed end; (v) the outer perimeter of the core; (vi) the amount of material detectable outside the outer perimeter of the core at the exposed end; (vii) the amount of impurity visible in the filtering material at the exposed end; (viii) the shape of the cross section of the longitudinal channel at the exposed end; (ix) the area of the exposed end having a specific colour or pigment; (x) the diameter of the exposed end; and (xi) the diameter of the longitudinal channel in the exposed end;