Digital Image Processing for Medical
Applications (1st Edition, 2009) – Solutions
Manual – Dougherty
What is the purpose of digital image processing? - answers-To optimise the digital image for
display using computer algorithms.
What are the three main stages of digital image processing? - answers-Pre-processing, default
(preset) processing, and post-processing.
What is pre-processing in digital imaging? - answers-Operations performed on raw image data
to correct imperfections and prepare it for display (e.g., flat-fielding, histogram creation).
What does a histogram represent in digital imaging? - answers-The range of digital pixel values
vs frequency; shows brightness (x-axis) and pixel count (y-axis).
What is the deviation index (DI)? - answers-A value reflecting the difference between the target
exposure and the actual exposure to the imaging receptor.
What is a lookup table (LUT) in digital imaging? - answers-A mapping applied to pixel values that
alters brightness and contrast (grayscale display) of a digital image.
What is automatic rescaling? - answers-A process that maps the full grayscale to the useful VOI
(volume of interest) to maintain consistent image brightness despite exposure variations.
What are some key display monitor specifications for diagnostic interpretation? - answers-For
example: 5-megapixel resolution, 54 cm diagonal size, 0.200 mm pixel pitch, luminance ratio >
1
, 250.
What does PACS stand for? - answers-Picture Archiving and Communication System.
What is DICOM? - answers-Digital Imaging and Communications in Medicine — a standard for
communication between imaging devices, PACS, and other systems.
What does HIPAA ensure in imaging informatics? - answers-Protection of patients' Protected
Health Information (PHI) and ensuring confidentiality, integrity and security of image data.
What is teleradiology? - answers-Remote interpretation of diagnostic images—images are
acquired in one place and interpreted in another, maintaining the same quality standards.
What are the two types of image compression? - answers-Reversible (lossless) and irreversible
(lossy).
What is lossy compression? - answers-Compression in which some image data is discarded to
reduce size, resulting in a loss of fidelity.
What is lossless (reversible) compression? - answers-Compression where no image information
is lost and the original image can be perfectly reconstructed.
What is window width in image display? - answers-The range of grayscale values included in the
display; increasing window width results in lower contrast.
What is window level (alias center)? - answers-The midpoint (center) of the grayscale range
displayed; adjusting it shifts the brightness of the displayed image.
2
Applications (1st Edition, 2009) – Solutions
Manual – Dougherty
What is the purpose of digital image processing? - answers-To optimise the digital image for
display using computer algorithms.
What are the three main stages of digital image processing? - answers-Pre-processing, default
(preset) processing, and post-processing.
What is pre-processing in digital imaging? - answers-Operations performed on raw image data
to correct imperfections and prepare it for display (e.g., flat-fielding, histogram creation).
What does a histogram represent in digital imaging? - answers-The range of digital pixel values
vs frequency; shows brightness (x-axis) and pixel count (y-axis).
What is the deviation index (DI)? - answers-A value reflecting the difference between the target
exposure and the actual exposure to the imaging receptor.
What is a lookup table (LUT) in digital imaging? - answers-A mapping applied to pixel values that
alters brightness and contrast (grayscale display) of a digital image.
What is automatic rescaling? - answers-A process that maps the full grayscale to the useful VOI
(volume of interest) to maintain consistent image brightness despite exposure variations.
What are some key display monitor specifications for diagnostic interpretation? - answers-For
example: 5-megapixel resolution, 54 cm diagonal size, 0.200 mm pixel pitch, luminance ratio >
1
, 250.
What does PACS stand for? - answers-Picture Archiving and Communication System.
What is DICOM? - answers-Digital Imaging and Communications in Medicine — a standard for
communication between imaging devices, PACS, and other systems.
What does HIPAA ensure in imaging informatics? - answers-Protection of patients' Protected
Health Information (PHI) and ensuring confidentiality, integrity and security of image data.
What is teleradiology? - answers-Remote interpretation of diagnostic images—images are
acquired in one place and interpreted in another, maintaining the same quality standards.
What are the two types of image compression? - answers-Reversible (lossless) and irreversible
(lossy).
What is lossy compression? - answers-Compression in which some image data is discarded to
reduce size, resulting in a loss of fidelity.
What is lossless (reversible) compression? - answers-Compression where no image information
is lost and the original image can be perfectly reconstructed.
What is window width in image display? - answers-The range of grayscale values included in the
display; increasing window width results in lower contrast.
What is window level (alias center)? - answers-The midpoint (center) of the grayscale range
displayed; adjusting it shifts the brightness of the displayed image.
2
