This webinar originally occurred on August 3rd, 2021
Duration: 1 hour
The ability to accurately and reliably analyze and compare forensic digital images relies on two key elements: image quality and image clarity. Most forensic examiners understand that resolution plays a key role in determining image quality; however, far too many examiners do not realize the impact that color (expressed in digital imaging terms as bit depth) has on evaluating the clarity between minute details in digital images. More specifically, insufficient resolution can impair the perceptual recognition of detail in a digital image, while the bit depth can impair the distinction between minute details in a digital image. Insufficient image quality and/or image clarity can render a digital image unusable for processing, analysis, and comparison. It can also invalidate the probative value of a digital image.
There are numerous variables that can affect both resolution and clarity of digital images. For example, the size of the imaging sensor in a digital camera affects the range of the lens, as well as the field of view (size of area captured). In addition, the file format used in the camera to store images can negatively affect image quality and clarity. The file format used to store processed images and the procedures used during image processing can also have a negative effect on image quality and clarity.
There are several other variables that will affect how a person visualizes the minute details in a digital image. The resolution (megapixels) of a digital image and the resolution of the monitor on which the image is displayed are two variables that affect the visualization of minute details. In other words, are you losing image data through resampling and/or compression when a digital image is displayed on a monitor or when digital images are shared amongst professionals?
Further, in terms of ANSI/NIST standards, the forensic science community must understand what is meant by “achievable resolution” or “resolving power.” This webinar helped audience members understand how resolution will impact an imaging system’s ability to distinguish between separate adjacent elements in an evidence impression. Lastly, the presenters taught audience members about digital imaging science and domain expertise to examine and interpret digital images accurately and reliably.
Detailed Learning Objectives:
- Understand the difference between image quality and clarity.
- Learn how to apply digital imaging technologies properly in their daily work.
- Be able to explain the fundamentals of image quality and clarity to various audiences, including other examiners, investigators, and juries.
Presenter: David “Ski” Witzke
Funding for this Forensic Technology Center of Excellence event has been provided by the National Institute of Justice.-
Please contact us at ForensicCOE@rti.org for any questions.
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