Detection of a random edge and its application to interior surface measurement

Zhige Zhang; Peter John Bryanston-Cross

doi:10.1117/12.258227

14 November 1996 Detection of a random edge and its application to interior surface measurement

Zhige Zhang, Peter John Bryanston-Cross

Proceedings Volume 2847, Applications of Digital Image Processing XIX; (1996) https://doi.org/10.1117/12.258227
Event: SPIE's 1996 International Symposium on Optical Science, Engineering, and Instrumentation, 1996, Denver, CO, United States

Abstract

A random edge is the center of an in-focus-strip which is formed by viewing a vertical surface through a conventional microscope. The in-focus-strip is the image of the surface which locates inside the depth of the field of the microscope. The image of the surface which locates outside of the depth of the field is blurred and contains only low frequency illumination profile. The location of this random edge has been used to make internal measurements within holes as small as 200 microns in diameter. A specialized edge detector has been designed to 'find' the center within the in-focused region. The detector first locates the in- focus-strip. It then extracts the surface background detail from the out-of-focus part of the image. This out-of-focus information is used to effectively normalize the intensity distribution over the image. The image is then smoothed to remove random noise. The location of the center of the in- focus-strip is then found from the application of a weighting function constructed from the position of individual details located within the edge region. This method has been used in measuring inside a 0.25 mm diameter hole. The hole is used to carry the coolant through a turbine blade. The accuracy of the measurement is better then +/- micrometers .

Citation Download Citation

Zhige Zhang and Peter John Bryanston-Cross "Detection of a random edge and its application to interior surface measurement", Proc. SPIE 2847, Applications of Digital Image Processing XIX, (14 November 1996); https://doi.org/10.1117/12.258227

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available