International Conference on Optical Measurement Techniques for Structures and Systems 2015 edition:6 location:Antwerp, Belgium date:8-9 April 2015
DIC measurements highly depend on the intensity interpolation of images to achieve subpixel accuracies. The intensity interpolation at subpixel positions is based on the grey levels sampled at integer pixels. Therefore, the sampling rate is crucial to the interpolated intensities. The sampling rate is restricted by the camera resolution. With insufficient resolution, the interpolated intensities at subpixel positions evidently differ from the reality, and significantly degrade the measurement quality. In order to deal with this problem, we propose to use super-resolution images to improve the measurement accuracy when the camera resolution is insufficient. The concept of super-resolution is using a bunch of low-resolution images of a specimen to construct a high-resolution image. In this way, the interpolation error due to insufficient sampling rate can be compensated.
The conversion from the low-resolution images to the high-resolution one will introduce certain error. But it can be tested that the introduced error is far less significant than the improvement. Specifically, the technique is of important value for applications with high/ultra-high speed cameras, whereof the resolution is usually much lower compared to low speed cameras.