医学成像与通信协议DICOM影像在各种显示介质上的一致性学术报告课件
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The Grayscale Consistency Problem:
Problems of Inconsistency
mass visible
mass invisible
VOI chosen on one display device Rendered on another with different display Mass expected to be seen is no longer seen
DICOM Singapore Seminar:
Consistent Presentation of Images:
The Grayscale Image Presentation Problem:
The appearance of grayscale images displayed on different types of softcopy display devices or printed on different types of hardcopy output devices has often been inconsistent.
Composite object containing the image display settings parameters Composite object links to one or more images (Series, filters); stored using same Study Instance UID (same Storage SOP Class!) Uses regular Storage services (C-STORE); uses Query/Retrieve services GSPS SOP Instances are immutable: changes require a new SOP Instance UID Note: generation and specific application of GSPS is outside the scope of DICOM, but not outside the scope of IHE (e.g. Virtual Image Set Split)
Printer Calibration Tools (Densitometer)
Perceptual Linearization
.01
.1
1
10
100
1000
0
200
400
600
800
1000
Grayscale Standard Display Function
JND Index
Same number of Just Noticeable Difference == Same perceived contrast
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Causes of Inconsistency
Gamut of device Minimum/maximum luminance/density Characteristic curve Mapping digital input to luminance/density Shape Linearity Ambient light or illumination
Mapping P-Values to Input of Characteristic Curve (DDL’s)
0
50
100
150
200
250
300
0
50
100
150
200
250
300
P-Values
DDL
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Despite different change in absolute luminance
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Monitor Characteristic Curve
Monitor Characteristic Curve
Example: A Radiologist “Flips” Chest XRAY Image on Softcopy Display
Suspected area
Example Continued: Radiologist Magnifies Chest XRAY Image, Pans to Upper Right Hand Quadrant and Adds an Annotation
Grayscale Softcopy Presentation Se:
What about color ?
Consistency is harder to achieve Not just colorimetry (i.e. not just CIELAB) Gamut of devices much more variable Greater influence of psychovisual effects Extensive standards efforts e.g. ICC DICOM is defining color presentation in a manner very similar to grayscale, but utilizing the ICC profiles instead of the GSDF, see Supplement 100. Many display and print devices already have ICC profiles, but few medical imaging devices support color presentation state.
Basic Print Management Meta SOP Class
Print (SCU)
Print (SCP)
Association Negotiation - “Contract Agreement”
Agreed set of SOP Classes and Transfer Syntaxes ( Basic Print Meta SOP Class)
Towards a Standard Display
Can’t use absolute luminance since display capabilities different Can’t use relative luminance since shape of characteristic curves vary Solution: exploit known characteristics of the contrast sensitivity of human visual system - contrast perception is different at different levels of luminance
Human Visual System
Model contrast sensitivity assume a target similar to image features confirm model with measurements Barten’s model Grayscale Standard Display Function: Input: Just Noticeable Differences (JNDs) Output: absolute luminance
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Problems of Inconsistency
0.5
1.5
1.0
3.0
Not all display levels are perceivable on all devices
Film Sheet
Basic Print Meta SOP Class consist of four SOP Classes (Film Session, Film Box, Image Box, and Printer)
N-Create (create film sheet, format printer)
0.1
1
10
100
0
50
100
150
200
250
DDL or P-Values
Standard
Characteristic Curve
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Standardizing a Display
Consistent Presentation is Provided by
Use of DICOM GSDF for calibration of monitors Use of Presentation LUT for Grayscale Print Creation of GSPS SOP Instances to capture the presentation of softcopy images. Use of GSPS SOP Instances when displaying images from archives ( Devices that claim conformance to IHE Consistent Presentation of Images provide these functions. )
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Problems of Inconsistency
Digital Modality
Laser Printer
Printed images don’t look like displayed images
Optimal image viewing parameters (e.g. window/ level) selected on one device appear different when displayed on a different device Device capabilities/ characteristics vary - the same number of gray levels cannot be rendered or perceived on different devices Displayed images look different from printed images …other
0.01
0.1
10
100
0
50
100
150
200
250
300
Digital Driving Level
Ambient Light
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Standardizing a Display
To Achieve Consistent Presentation of Images, the DICOM Standard Defines:
Basic Print Management with Presentation Look Up Table, for controlling the consistent appearance of preformatted images on printed output Grayscale Softcopy Presentation State, for controlling the consistent appearance of images on softcopy display
N-Set (place images on film sheet)
N-Action (request to print the film sheet)
N-Event-Report (status of the printer)
Slide Provided by Don Van Syckle, Merge Technologies Inc.
Problems of Inconsistency
mass visible
mass invisible
VOI chosen on one display device Rendered on another with different display Mass expected to be seen is no longer seen
DICOM Singapore Seminar:
Consistent Presentation of Images:
The Grayscale Image Presentation Problem:
The appearance of grayscale images displayed on different types of softcopy display devices or printed on different types of hardcopy output devices has often been inconsistent.
Composite object containing the image display settings parameters Composite object links to one or more images (Series, filters); stored using same Study Instance UID (same Storage SOP Class!) Uses regular Storage services (C-STORE); uses Query/Retrieve services GSPS SOP Instances are immutable: changes require a new SOP Instance UID Note: generation and specific application of GSPS is outside the scope of DICOM, but not outside the scope of IHE (e.g. Virtual Image Set Split)
Printer Calibration Tools (Densitometer)
Perceptual Linearization
.01
.1
1
10
100
1000
0
200
400
600
800
1000
Grayscale Standard Display Function
JND Index
Same number of Just Noticeable Difference == Same perceived contrast
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Causes of Inconsistency
Gamut of device Minimum/maximum luminance/density Characteristic curve Mapping digital input to luminance/density Shape Linearity Ambient light or illumination
Mapping P-Values to Input of Characteristic Curve (DDL’s)
0
50
100
150
200
250
300
0
50
100
150
200
250
300
P-Values
DDL
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Despite different change in absolute luminance
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Monitor Characteristic Curve
Monitor Characteristic Curve
Example: A Radiologist “Flips” Chest XRAY Image on Softcopy Display
Suspected area
Example Continued: Radiologist Magnifies Chest XRAY Image, Pans to Upper Right Hand Quadrant and Adds an Annotation
Grayscale Softcopy Presentation Se:
What about color ?
Consistency is harder to achieve Not just colorimetry (i.e. not just CIELAB) Gamut of devices much more variable Greater influence of psychovisual effects Extensive standards efforts e.g. ICC DICOM is defining color presentation in a manner very similar to grayscale, but utilizing the ICC profiles instead of the GSDF, see Supplement 100. Many display and print devices already have ICC profiles, but few medical imaging devices support color presentation state.
Basic Print Management Meta SOP Class
Print (SCU)
Print (SCP)
Association Negotiation - “Contract Agreement”
Agreed set of SOP Classes and Transfer Syntaxes ( Basic Print Meta SOP Class)
Towards a Standard Display
Can’t use absolute luminance since display capabilities different Can’t use relative luminance since shape of characteristic curves vary Solution: exploit known characteristics of the contrast sensitivity of human visual system - contrast perception is different at different levels of luminance
Human Visual System
Model contrast sensitivity assume a target similar to image features confirm model with measurements Barten’s model Grayscale Standard Display Function: Input: Just Noticeable Differences (JNDs) Output: absolute luminance
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Problems of Inconsistency
0.5
1.5
1.0
3.0
Not all display levels are perceivable on all devices
Film Sheet
Basic Print Meta SOP Class consist of four SOP Classes (Film Session, Film Box, Image Box, and Printer)
N-Create (create film sheet, format printer)
0.1
1
10
100
0
50
100
150
200
250
DDL or P-Values
Standard
Characteristic Curve
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Standardizing a Display
Consistent Presentation is Provided by
Use of DICOM GSDF for calibration of monitors Use of Presentation LUT for Grayscale Print Creation of GSPS SOP Instances to capture the presentation of softcopy images. Use of GSPS SOP Instances when displaying images from archives ( Devices that claim conformance to IHE Consistent Presentation of Images provide these functions. )
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Problems of Inconsistency
Digital Modality
Laser Printer
Printed images don’t look like displayed images
Optimal image viewing parameters (e.g. window/ level) selected on one device appear different when displayed on a different device Device capabilities/ characteristics vary - the same number of gray levels cannot be rendered or perceived on different devices Displayed images look different from printed images …other
0.01
0.1
10
100
0
50
100
150
200
250
300
Digital Driving Level
Ambient Light
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Standardizing a Display
To Achieve Consistent Presentation of Images, the DICOM Standard Defines:
Basic Print Management with Presentation Look Up Table, for controlling the consistent appearance of preformatted images on printed output Grayscale Softcopy Presentation State, for controlling the consistent appearance of images on softcopy display
N-Set (place images on film sheet)
N-Action (request to print the film sheet)
N-Event-Report (status of the printer)
Slide Provided by Don Van Syckle, Merge Technologies Inc.