Identifying the substrate type of a target substrate before patterning by a marking engine produces an opportunity to adjust the marking engine. The adjustments can enable the marking engine to produce higher quality work. The target substrate's substrate type can be automatically identified by obtaining its characteristics and submitting them to a classifier. A spectrophotometer can measure a substrates reflectance spectrum, which is a good characteristic for use in classifying. Classifiers can be based on known distance or correlation measures.