Netherlands Institute for Conservation, Art and Science

Workshop Automatic Thread Counting

By Prof. Don H. Johnson

28May2019 12:30 - 18:00


Don Johnson is coming to Amsterdam on the 28th of May 2019, offering a workshop for the field on automatic thread count.

Location: Ateliergebouw, Lecture Room B

Thread counting  — measuring the densities of the vertical and horizontal threads that comprise artist canvas — was developed by Ernst van de Wetering over thirty years ago as a way of comparing the canvases of two paintings to determine if they could have come from the same canvas roll. Because many paintings are lined, he manually “counted threads” over a short distance at several locations using x-radiographs that revealed the canvas. Much later, Professor C. Richard (Rick) Johnson, Jr. of Cornell University asked Professor Ella Hendriks what technique of technical art history could be enhanced by computerization. She suggested thread counting. Thus was formed the Thread Count Automation Project (TCAP) that resulted in the software being used today. Instead of measuring thread densities at a few locations manually, computer algorithms now measure thread densities everywhere on painting’s area.


The workshop will hand out the thread counting software to all participants (both Windows and macOS are supported), demonstrate how to use it and show how it can be used for canvas analysis. Not only does the software measure the thread counts of individual paintings, it also can compare two painting's thread density patterns looking for a match, allows analysis of multi-canvas paintings, reveals cusping patterns and helps determine if edges have been trimmed. Participants should bring their laptops. The workshop will begin with software installation followed demonstrating the software is used on actual examples.



A biography of Don H. Johnson can be found here.

Course fee

This course is free of charge.

Maximum number of participants

The maximum number of participants is 25. We will work with a waiting list on a first come, first serve basis. Since the Ateliergebouw is a heavily secured building, please make sure to bring your ID.


A more detailed programme will be announced shortly.


For more information, please contact the secretariat of the University of Amsterdam programme for Conservation and restoration.

Published by  NICAS