Digital Imaging Flashcards
What are the forensic image capturing devices?
Cameras
Video
Scanners
How do digital cameras sensors capture images?
The sensor is made up of light sensors
Light sensors create pixels by sensing the light intensity of small portions of images
Can only record in grey scale
What are the 3 primary colours in the sensors?
RBG
Red
Blue
Green
What are the three pixel properties?
Location
Size
Colour value
What sensor size do we use for forensic photography?
FX - full frame
What are the three common file formats with digital cameras?
JPEG
TIFF
RAW
What are somethings about JPEG photos
Joint Photographic Experts Group
They are compressed - lossy
Good for long turn storage
8 bit per channel from camera
What are somethings about TIFF images?
Tagged Image File Format
Lossless
Very large file size
Working copy of images
12/14 bit per channel
What are somethings about RAW photos?
No compression
Much smaller file size that TIFF
No processing by ca,era software
Can’t be changes or altered
12 bit capture
What effects a file size of an image
Number of pixels
Colour depth
Colour mode (number of channels; RGB, CMYK, greyscale)
File format
What affects image quality?
Resolution
Colour bit path (16 bit vs 8 bit)
Lens
Size of CCD (sensor)
File format
Colour interpolation
Processing of the image
Pixel size
The number of pixels affects the quality of the image
More pixels = better imaging in enlarging
Photoshop Resizng
The number of actual pixels remains the same
Only the size of the pixel changes as enlarged or shrunk
The number of pixels per inch will change as image is resized
Image resolution
The number of pixels per inch will affect the image quality
What is calibration?
It is a method of resizing an image so it correlates to an actual given value
Must have a properly photographed scale
Can be printed life size or to scale
