Density Doubling Image Equalization Macro for ImageJ

  • Author(s) / Creator(s)
  • In order to adapt images of patterns templated using block copolymers, acquired using a scanning electron microscope, for publication, an algorithm was developed to process the images, enhancing the darker features in a consistent and easily reproducible manner. This was done using ImageJ, a free and open source scientific image processing program. In order to maintain transparency in this process, the macro code is made available for inspection and use by others. Image equalization process description: SEM images of the double layer structures were enhanced to aid visualization of the darker structures templated by the lower-layer of cylinders by a process designed to “equalize” the image histogram as shown in Figure S8. A median filter with a 2-pixel radius was first applied over the image to reduce noise. It should be noted that good SEM images of double layer templated line structures ideally possess a trimodal histogram due to the varying intensities of structures templated from the upper and lower layers of cylinders, as contrasted with the substrate; using a median filter has the additional advantage of enhancing the separation of the three ranges of values (peaks in the histogram). Next, the brightness and contrast were automatically adjusted to expand the range of the histogram over the entire range of values (from 0 to 255 for these 8-bit images). Consequently, the bright lines (templated by the upper-layer cylinders) will have values near 255; the spaces between the lines having values near 0; and the darker lines (templated by the lower-layer cylinders) will have some intermediate value (in the case of Figure S8, the values are around 74). For increased contrast between the darker lines, templated by the lower layer, and the substrate, these intermediate pixel values were adjusted to have their intensity centered at approximately 128 by mapping the pixels to redistribute the intensity values using bi-linear interpolation based on the initial value found and selected for the darker lines.

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  • Type of Item
    Research Material
  • DOI
  • License
    This code is licensed using the \"MIT License\", available...
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  • Citation for previous publication
    • Nathanael L.Y. Wu, Xiaojiang Zhang, Jeffrey N. Murphy, Jinan Chai, Kenneth D. Harris & Jillian M. Buriak, "Density Doubling of Block Copolymer Templated Features", Nano Letters, in press.