Forensic Digital Image Processing

Three areas of processing :

1. Dealing with specific defects resulting from hardware (camera, video, or scanner)
2. Visibility enhancement of image details
3. Software techniques (i.e. Photoshop)
   • tonality
   • exposure
   • filters
   • plugins
   • channels
   • color space
   • deconvultion

Regardless of method. We can't remove or add details in a forensic workflow.

Common problems in images

• Poor resolution
  • zooming does not help
  • interpolation does not help
• Poor contrast (exposure problems)
• Poor tonal range
• Noise (quality of CCDs, lightsource, recording media)
• Blur (motion, focus)
• Interlacing (misalignment of lines)

Enhancing Images

• Tonal adjustment
• Equalization
• Histogram remapping
• Contrast adjustment
• Gamma correction (midtone adjustment)
• Sharpening
• Denoising
• Deblurring
• Frequency filtering
• Deconvolution
• Exploiting ridge patterns
• Focusing