He is known for his portraits, often used as book frontispieces.

He has also published a book on book frontispieces and cover pages dedicated to him by personal friends Gerald Durrell and Lawrence Durrell.

Influence from Byzantine visual vocabulary (blue and gold coloring, angelic and victorious motifs, symbology of drapery) combined with Mongoloid facial types in 12th-century book frontispieces.

Pyle helped secure commissions for his students, and Ashley's early work included book frontispieces and illustrations for magazines such as The Delineator, Leslies, McClure's, and Success.

He produced the German chiaroscuro woodcut with the most different colour blocks, a seven-block coat of arms of a cardinal, for a book frontispiece of 1520, probably cut by Jost de Negker.

In the 1630s he produced a number of portrait engravings and book frontispieces, depicting Puritan divines, poets, and figures associated with the High Church establishment of the day, such as William Laud.

Several other paintings of this period are related to this work: The Inspiration of Anacreon, the Parnassus, and the book frontispiece drawn by Poussin and engraved by Claude Mellan for an edition of Virgil published by the Imprimerie Royale in 1641-1642.