ITKMontage: A Software Module for Image Stitching

Stitching partially overlapping image tiles into a montage is a common requirement for materials microscopy. We developed ITKMontage, a new module for the open-source Insight Toolkit (ITK), capable of robustly and quickly generating extremely large, high-bit-depth montages within the memory constraints of standard workstations. The phase correlation method is at the core of our pairwise tile registration algorithm. Precise alignment of tiles acquired in typical raster patterns is enhanced with sub-pixel fitting and cropping to overlap. Fast Fourier transform (FFT)-based correlation is improved through a variety of padding methods and an added adjustable bias toward an expected translation. To arrange the tiles into the overall montage, we use global least squares minimization with outlier detection and removal. To blend tiles smoothly, each tile's contribution is weighted by the distance from the tile's edge. Results are demonstrated on several material science data sets and 3D images. Results compare favorably to ImageJ/Fiji plugin Image Stitching. The tool is integrated into the DREAM.3D software suite for multidimensional, multimodal microstructural data.