#Piv tool imagej windows

The search window size should always be larger or equal to the interrogation window. Using 1/4 the image dimension for the 1st interrogation window could be a good starting point. Please refer to the installation section for more detail.īy default, you can do 3 passes of PIV, with decreasing interrogation window size. It is highly recommended to use this plugin with the template matching method in order to obtain better result. Second, the normalized algorithm is less sensitive to background intensity variation and allows one to define a threshold to distinguish high and low image correlations, so that the correlation made on small interrogation window presenting insufficient features which tends to be erroneous can be easily filtered out and replaced by interpolated value.

The PIV information from previous round only served as a guidance for determining the correlation peak. It has several advantages: first, the interrogation window is compared against a larger searching window, ensuring the feature (image under the interrogation window) will be presented in the searching area. The second method employs the template matching method using normalized correlation coefficient algorithm.

#Piv tool imagej windows

However, if this window preshift value was not correct, then the subsequent PIV could be made on two irrelevant interrogation windows and cause erroneous result. Each PIV result will serve as window preshift for the next PIV iteration, so that large displacement could still be catch when small interrogation window was used. As a result, only interrogation window with a power of 2 size will be accepted.

It is a rather primitive implementation using the ImageJ's built-in FHT.conjugateMultiply function. The first one is the most conventional cross-correlation method. This iterative PIV program implements two methods for image correlation.