Pre-Processing > Similarity > Pattern Mapping

Processes and colors pixels based on their surrounding image pattern. Produces a grayscale map of the pattern indicator for further processing into an ultimate selection.

Available tools for pattern analysis are local two-point correlation properties, mapping of selected FFT intensities, and matching of local FFTs to selected references. This function can take some time to complete depending on the size of the image and Window Size parameter.

After first clicking “Calculate”, a parallel-pool of CPU resources will be created which may take several seconds. This parallel-pool is good for 30 minutes and will not have to be re-created within that time. It is recommended that this function not be run on images larger than 1200×900, and that the window size be kept to 40 pixels or less.

1. Method

  • Two-Point Correlation: Calculates the two-point correlation function at each pixel, using a surround window of a specified size. The orientation, size, and shape of the “hotspot” of a pixel-window’s two-point correlation tell you information about the window’s local directionality, the extent of that directionality, and the size of features within the window.
  • FFT Mapping: Allows you to define a mask to place around the FFT taken about each pixel, and either sum the intensities or take the peak intensity within the mask. This measurement is then assigned to each pixel. In essence, you are mapping out traits about each pixel’s local FFT, which can reveal local pattern differences in the image. The size of the window taken about the click to define the mask is determined by Window Size. It is often advised to set a large Window Size prior to clicking to define the mask, and then reducing the Window Size to something much smaller to perform the mapping.
  • FFT Matching: Allows to define a fixed number of reference FFTs (i.e., “fingerprints”) by clicking points within the image. The size of the window taken about each click to define the “fingerprints” is determined by Window Size . Each pixel’s local FFT is then compared to each “fingerprint”, and labeled according to which “fingerprint” it matched the best.

2. Window Size

Window size to consider about each pixel for the pattern map

3. Speed

Controls the speed of the pattern mapping by increasing or decreasing the degree of downsampling

4. Metric

Mapped parameter to display

5. Colormap and Limits

Colormap to use for display, along with upper and lower limits for the colormap. Click “Auto” to automatically set the default limits.

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