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1 • Summary 
The problems involved in measuring, interpreting and 
applying transfer functions are more complex and difficult 
than is generally believed. While transfer functions 
provide powerful tools for the designer and research worker, 
their adoption will not immediately solve the general prob 
lem of specifying image quality. Given adequate instru 
mentation, the performance of lenses could be specified 
and controlled more accurately and completely by transfer 
functions than by resolving power. 
In furthering the wider use of transfer functions in 
photogrammetry it will be necessary to advance on a limited 
front, concentrating first on camera lenses and the instru 
mentation required to achieve sin as yet unrealized agreement 
between measurements made in different laboratories. 
The Working Group recommends continued interlaboratory 
tests to establish measurement accuracies. 
2. Terms of Reference 
At the tenth ISP Congress, Lisbon 1964, Commission I 
was asked to study the application of transfer functions to 
image quality. 
Resolution 1.5 of Commission I reads: 
Because of the potential advantages of 
the optical transfer function as an 
objective method of measuring image 
quality, Commission I should give fur 
ther consideration to the present status 
of the method, its limitations, accuracy 
and the necessary test equipment. In 
so doing it should consider not only 
aerial cameras but all image-forming and 
recording systems used in photogrammetry. 
The Commission should also aim the work 
towards having an agreed method to be 
incorporated in the ISP "Recommendations 
on Camera Calibration" at the 1968 ISP 
Congress". 
This report records the conclusions and recommendat 
ions of the Working Group which has been studying these 
questions.