IMGBalance: the program for correction of brightness irregularities (shadows) on SEM BSE images of flat samples using approximating interpolant for irregular grid calculated by modified Shepard-Renka method

 This freeware can be used for correction of brightness irregularities (shadows) on SEM images (mostly BSE images) of flat samples produced by our JEOL JSM-6510LA microscope (i.e. on IMG-files). However, it may be used for any indexed (paletted) grayscale BMP images, too. As usual, such shadows look like gradual image darkening towards one side or corner due to poor hardware adjustments, large sample slope and small magnification in combination with specific design features of the microscope. These shadows are especially harmful on composite mosaic images combined from a large number of small individual fragments:

Before correction
Before balancing
After correction
After balancing

 The main idea of correction is very simple: at first, user must create "mask" - a special additional image reflecting brightness variations. Masks are calculating from user-specified sets of small areas having the same intensity, e.g. those that belong to the same phase demonstrating uniform composition. Then, user can apply this mask to all appropriate images of the project/sample.

IMGBalance works with images only. However, the proposed idea may be extended to a more sophisticated methods, e.g. taking into account measured chemical compositions through the explored area (compositional maps) for automatic selection of sampling areas.

IMGBalance uses modified Shepard-Renka method for calculation of approximating interpolant for irregular grid. Implementation of this method (for noisy data) has been taken from the ALGLIB® math library ( of Sergey Bochkanov and Vladimir Bystritsky. The program is distributed under the terms of the GNU General Public License (GPL).