The evidential value of distorted and rectified digital images in footwear imprint examination

• Published in: Forensic science international 2006-06, Vol.160 (1), p.59-65
• Main Authors: Shor, Yaron, Chaikovsky, Alan, Tsach, Tsadok
• Format: Article
• Language: English
• Subjects: Analysis; Biological and medical sciences; Digital cameras; Digital photography; Evidence, Scientific; Footprints; Footwear; Forensic medicine; Forensic Medicine - methods; Forensic science, Digital photography, Rectified image, Distorted shoeprints; Forensic sciences; General aspects; Humans; Image Processing, Computer-Assisted; Investigative techniques, diagnostic techniques (general aspects); Medical sciences; Methods; Photography; Public health. Hygiene; Public health. Hygiene-occupational medicine; Shoes; Software
• ISSN: 0379-0738; 1872-6283
• DOI: 10.1016/j.forsciint.2005.08.017

The procedure for forensic photography requires that the film plane be parallel to the taken image. Another procedure must be used when the print is located on reflecting surfaces such as vehicles, or faint marks on porous surfaces. Examination was made of the evidential value of footprint images received from the scene or taken deliberately at an angle out of proper perspective (i.e., the lens axis is not perpendicular to the target plane). An artificial target was prepared and photographed from several lens axis angles ranging from 10° to 85° to the perpendicular, and then rectified using the Adobe Photoshop Version 7.0 ®. It was found that at angles less than 40°, the shape and location of all the individual characteristics were similar enough in comparison to the original image. In images taken at higher angles, the original image could not be adequately restored. The full potential of this image, therefore, could not be achieved after rectification. The results of this study show that the images of a footprint taken at an angle less than 40°, preserve the evidential value of the unique characteristics.