The libraries from which images were ordered received a copy of CFEO’s digitisation specifications. Not all were able to supply material at the defined standards, however, while others agreed to supply images to CFEO at a lower resolution (e.g. 300 ppi) than the one requested by the project team. For this reason, users will notice some variability in the quality of first-edition images within the CFEO resource. (Compare, for instance, the images of the three different editions of the Mazurkas Op. 17, likewise those of the Ballade Op. 23.) Although CFEO has made every effort to ensure consistency across this large virtual collection, such variability is inevitable given that the c. 5,500 images in CFEO were obtained from over twenty different suppliers.

Most participating institutions employed in-house digitisation staff, but in some cases the scanning or digital photography was outsourced. For example, PL-Wn digitised the Chopin editions held by PL-Wbfc and PL-Wmfc (formerly in the collection of the Towarzystwo imienia Fryderyka Chopina), PL-Wtm and PL-Wekier. (See the abbreviations listed under library and other sigla.) Lynda Sayce (employed on DIAMM) photographed the material held by GB-Lam, while Schecter Lee digitised US-NYpm’s editions.

Only one institution – the Verlagsarchiv of B. Schott’s Söhne in Mainz – actively declined to participate in CFEO; that is why no score of the Polish first edition of the Waltz in E minor appears in CFEO, as it has been impossible to locate an equivalent source elsewhere. (See the Annotated Catalogue of Chopin’s First Editions.) Despite repeated approaches, CFEO received no response from the Gesellschaft der Musikfreunde in Vienna (whose score of the Concerto Op. 21 published by Breitkopf & Härtel could however be substituted by an exact counterpart from the Biblioteka Jagiellońska, Cracow) or from the Museo de Fryderyk Chopin y George Sand in Valldemossa (hence the absence of Cramer, Beale & Co.’s edition of the Waltz Op. 64 No. 3).

Users occasionally will find that the images of certain pages listed in the work index are unavailable. This is usually because the institution holding the score in question could not supply digital images thereof – for example, if these pages were missing from the original itself. CFEO regrets any inconvenience caused to users.