SWGIT Flashcards
What does SWGIT stand for?
Scientific Working Group on Imaging Technology
What is the mission of SWGIT?
to facilitate the integration of imaging technologies and systems within the criminal justice system by providing definitions and recommendations for the capture, storage, processing, analysis, transmission, and output of images
Describe the membership of SWGIT
Those selected for membership in the group are experienced professionals working in the field of imaging technology or a related field and demonstrate the willingness to participate by consulting on the release of best practices and guidelines for the use of imaging technology in the Criminal Justice System.
What is the purpose of the SWGIT document?
To familiarize the reader with important considerations in the capture, preservation, processing, and handling of images, no matter the image type and where they can find related guidelines and details.
What are the basic requirements for the admission of digital images?
The images must be relevant, properly authenticated digital images that accurately portray a scene or object are admissible in court
What is image compression?
Compression is the process of reducing a digital file’s size.
What are the two types of compression?
The two types are lossy and lossless
What is Lossy compression?
When lossy compression is used, critical image information can be lost and unwanted artifacts introduced as a result. Can also result from multiple saves.
What is lossless compression?
Does not affect the image information as much. Is the preferred type of photo when it is subjected to scientific analysis
The requirement that an exhibit (image) be authenticated is usually satisfied when what?
An exhibit is authenticated when there is sufficient evidence that the exhibit is what the proponent claims it to be (i.e witnesses in the case can do this)
In the case of images processed using advanced equipment techniques, ________ witnesses must be able to testify concerning the ____ ____.
In the case of images processed using advanced equipment techniques, qualified witnesses must be able to testify concerning the processed used.
Define a “primary” image as opposed to an “original” image
A primary image refers to the first instance in which an image is recorded onto any media that is a separate identifiable object. An original image is an accurate and complete replica of the primary image, irrespective of media.
According to SWGIT, original images should not be _________.
altered in any way
Processing should be performed on _________ images only
working
What are the 5 methods for maintaining integrity?
- Written Documentation
- Physical Security / Environment
- Redundant Physical Copies
- Logical Security (WAN / LAN)
- Third-Party Escrowing
What are the 2 simple and approved methods that to not require technology for demonstrating integrity?
Visual Verification & Written Documentation
To achieve maximum detail, it is the best practice to _________ the _______________ with the impression.
Fill the frame
The minimum pixels per inch (ppi) resolution to capture a latent print is _________________.
1000 pixels/inch at 1:1
Given that the 7D camera has a pixel resolution of 5184 x 3456, what is the maximum field of view that will yield the minimum resolution for a latent print?
It is recommended to capture using _____ ___________________ or ___________________ _________________.
compression or lossless compression (e.g. RAW or TIFF)
In regards to the first photograph… When appropriate (e.g. crime scene), capture overall view of impression area _________________ ___ scale, using proper lighting
without a scale
In regards to subsequent photos… Capture overall view of impression ____________ ____ scale, using proper lighting.
with a scale
The camera must be placed at a _____ degree angle to the impression.
90˚
The scale must be placed on the same _________________ and ____ __________ ___ _______________ to impression without ____________________ _________________.
on the same plane; as close as possible; obscuring detail.
The scale may contain 6 bits of information to identify the print. What are those bits of information?
a) Case number or unique identifier
b) Date
c) Initials
d) Source
e) Process used
f) Location/orientation
At a minimum, the scale should have the date and the initials of the photographer.
What is the minimum megapixel native resolution recommended?
eight (8)
Two sets of overall, mid-range and close-up photographs should be taken. What is the difference between the two sets?
One has markers and scales and the other does not
How should the camera be positioned relative to the impression?
parallel and 90˚
Where should the lens be focused on the impression?
Bottom of the impression
What f-stop setting is recommended for optimum depth of field and image sharpness?
generally two stops below the largest f-stop
Scale should be on the same level as what?
as the impression.
What formats of compression are required?
uncompressed or lossless
compression. (e.g. RAW or TIFF)
In addition to an overall footwear impression photograph, what areas of the footwear should be photographed separately close-up?
the heel and toe box area should be taken
What is the procedure for photographing long tire impressions and what type of scale should be used?
a series of overlapping photographs of 12 inches each
should be taken; a tape measure
It is recommended that lighting be rotated around a footwear impression to capture detail on the bottom of the impression. What is the minimum number of images that should be taken with different lighting? What is the spacing of the light in degrees as it is rotated around the print?
3 images; 100 degrees
