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. Author manuscript; available in PMC: 2015 Oct 1.
Published in final edited form as: Comput Biol Med. 2014 Jul 26;0:134–140. doi: 10.1016/j.compbiomed.2014.07.010

Fig. 4.

Fig. 4

Intermediate and final results of the PHI detection and redaction processes. (a) The subregion of the original un-altered radiograph as described in Fig. 3. (b) The original image after application of the interpolation-OCR method, involving a brightness threshold filtering followed by bicubic interpolation. This image was tested with OCR algorithms without success. The threshold-redaction algorithm was as follows, with the step letter indicating the corresponding sub-figure: (c) The original image after application of a low-threshold filter. (d) The original image after application of a high-threshold filter. (e) An image obtained after performing a single pixel expansion of image 4d and subtract it from image 4c. (f) Determination of bounding boxes overlaid on the original image. (g) Redacted of alpha-numeric information inside the bounding boxes suing a checkerboard pattern applied to the original image.