Post on 25-Dec-2015
DICOM Singapore Seminar:DICOM Singapore Seminar:
Author:Author:
Rob HornRob Horn
Agfa HealthcareAgfa Healthcare
Chair, DICOM WG-06Chair, DICOM WG-06
Consistent Presentation of Images:Consistent Presentation of Images:
Presenter:Presenter:
Kevin O’DonnellKevin O’Donnell
Toshiba Medical Systems CompanyToshiba Medical Systems Company
Member, DICOM WG-06Member, DICOM WG-06
The Grayscale Image Presentation The Grayscale Image Presentation Problem: 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.
Optimal image viewing parameters (e.g. window/ level) Optimal image viewing parameters (e.g. window/ level) selected on one device appear different when displayed selected on one device appear different when displayed on a different deviceon a different device
Device capabilities/ characteristics vary - the same Device capabilities/ characteristics vary - the same number of gray levels cannot be rendered or perceived number of gray levels cannot be rendered or perceived on different deviceson different devices
Displayed images look different from printed imagesDisplayed images look different from printed images ……otherother
The Grayscale Consistency Problem: The Grayscale Consistency Problem:
Problems of InconsistencyProblems 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
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Problems of InconsistencyProblems of Inconsistency
0.5
1.5
1.0
3.0
•Not all display levelsare perceivable on alldevices
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Problems of InconsistencyProblems of Inconsistency0.5
1.5
1.0
3.0
•Not all display levelsare perceivable on alldevices
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Problems of InconsistencyProblems of Inconsistency
Digital Modality Laser Printer
•Printed images don’t looklike displayed images
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Causes of InconsistencyCauses of Inconsistency
Gamut of deviceGamut of device– Minimum/maximum luminance/densityMinimum/maximum luminance/density
Characteristic curveCharacteristic curve– Mapping digital input to luminance/densityMapping digital input to luminance/density– ShapeShape– LinearityLinearity
Ambient light or illuminationAmbient light or illumination
Causes of InconsistencyCauses of Inconsistency
1.0 .66
•Display devicesvary in the maximumluminance they canproduce
•Display CRT vs. film on a light box is an extreme example
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Towards a Standard DisplayTowards a Standard Display
Can’t use absolute luminance since display Can’t use absolute luminance since display capabilities differentcapabilities different
Can’t use relative luminance since shape of Can’t use relative luminance since shape of characteristic curves varycharacteristic curves vary
Solution: exploit known characteristics of Solution: exploit known characteristics of the contrast sensitivity of human visual the contrast sensitivity of human visual system - contrast perception is different at system - contrast perception is different at different levels of luminancedifferent levels of luminance
Human Visual SystemHuman Visual System
Model contrast sensitivityModel contrast sensitivity– assume a target similar to image featuresassume a target similar to image features– confirm model with measurementsconfirm model with measurements– Barten’s modelBarten’s model
Grayscale Standard Display Function:Grayscale Standard Display Function:– Input: Just Noticeable Differences (JNDs)Input: Just Noticeable Differences (JNDs)– Output: absolute luminanceOutput: absolute luminance
Printer Calibration Tools Printer Calibration Tools (Densitometer)(Densitometer)
Display Calibration Tools Display Calibration Tools (Photometer)(Photometer)
Slide Provided by Jerry Gaskill, Image Smiths Inc.
Perceptual LinearizationPerceptual 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
Despite different changein absolute luminance
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Monitor Characteristic CurveMonitor Characteristic Curve
Monitor Characteristic Curve
0.01
0.1
10
100
0 50 100 150 200 250 300Digital Driving Level
Ambient Light
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Standard Display FunctionStandard Display Function
.01
.1
1
10
100
1000
0 200 400 600 800 1000
Grayscale Standard Display Function
JND Index
Monitor’s Capability
Jmax == P-Value of 2n-1
Jmin == P-Value of 0
Minimum Luminance+ Ambient Light
Maximum Luminance+ Ambient Light
Slide Provided by David Clunie, Quintiles Intelligent Imaging
Standardizing a DisplayStandardizing a Display
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 DisplayStandardizing a Display
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
DD
L
Slide Provided by David Clunie, Quintiles Intelligent Imaging
To Achieve Consistent Presentation of To Achieve Consistent Presentation of Images, the DICOM Standard Defines:Images, the DICOM Standard Defines:
Basic Print Management with Presentation Look Basic Print Management with Presentation Look Up Table, for controlling the consistent Up Table, for controlling the consistent appearance of preformatted images on printed appearance of preformatted images on printed outputoutput
Grayscale Softcopy Presentation State, for Grayscale Softcopy Presentation State, for controlling the consistent appearance of images controlling the consistent appearance of images on softcopy displayon softcopy display
Basic Print Management Meta SOP ClassBasic Print Management Meta SOP Class
Print (SCU)Print (SCU) Print (SCP)
Association Negotiation - “Contract Agreement”Association Negotiation - “Contract Agreement”
Agreed set of SOP Classes and Transfer SyntaxesAgreed set of SOP Classes and Transfer Syntaxes( Basic Print Meta SOP Class)( Basic Print Meta SOP Class)
Film SheetFilm Sheet
Basic Print Meta SOP Class consist of four SOP ClassesBasic Print Meta SOP Class consist of four SOP Classes(Film Session, Film Box, Image Box, and Printer)(Film Session, Film Box, Image Box, and Printer)
N-Create (create film sheet, format printer)N-Create (create film sheet, format printer)
N-Set (place images on film sheet)N-Set (place images on film sheet)
N-Action (request to print the film sheet)N-Action (request to print the film sheet)
N-Event-Report (status of the printer)N-Event-Report (status of the printer)
Slide Provided by Don Van Syckle, Merge Technologies Inc.
Example: A Radiologist “Flips” Example: A Radiologist “Flips” Chest XRAY Image on Softcopy DisplayChest XRAY Image on Softcopy Display
Suspected
area
Example Continued: Radiologist Magnifies Example Continued: Radiologist Magnifies Chest XRAY Image, Pans to Upper Right Chest XRAY Image, Pans to Upper Right Hand Quadrant and Adds an AnnotationHand Quadrant and Adds an Annotation
Referring Physician:Radiologist:
Suspected
area
Example Continued: Referring Physician Example Continued: Referring Physician Views the Original Image…Views the Original Image…
Radiologist Should Store the Viewing Parameters Using GSPS!Radiologist Should Store the Viewing Parameters Using GSPS!
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)
Grayscale Softcopy Presentation State:Grayscale Softcopy Presentation State:
IEIE ModuleModule UsageUsage
PatientPatient PatientPatient MM
StudyStudy General StudyGeneral Study MM
Patient StudyPatient Study UU
SeriesSeries General SeriesGeneral Series MM
Presentation SeriesPresentation Series MM
EquipmentEquipment General EquipmentGeneral Equipment MM
PresentationPresentation Presentation StatePresentation State MM
Modality LUTModality LUT C - Required if to be appliedC - Required if to be applied
MaskMask C - Required if multi-frame and to be appliedC - Required if multi-frame and to be applied
VOI LUTVOI LUT C - Required if to be appliedC - Required if to be applied
Softcopy Presentation LUTSoftcopy Presentation LUT MM
Graphic AnnotationGraphic Annotation C - Required if to be appliedC - Required if to be applied
Spatial TransformationSpatial Transformation C - Required if rotation, flipping or magnification are to be appliedC - Required if rotation, flipping or magnification are to be applied
Displayed AreaDisplayed Area MM
Display ShutterDisplay Shutter C - Required if to be applied and the Bitmap Display Shutter Module is notC - Required if to be applied and the Bitmap Display Shutter Module is notpresentpresent
Bitmap Display ShutterBitmap Display Shutter C - Required if to be applied and the Display Shutter Module is not presentC - Required if to be applied and the Display Shutter Module is not present
Overlay PlaneOverlay Plane C - Required if to be applied or the BM C - Required if to be applied or the BM Displ. Shutter Module is presentDispl. Shutter Module is present
Overlay/Curve ActivationOverlay/Curve Activation C- Required if image contains curve or overlay which is to be displayedC- Required if image contains curve or overlay which is to be displayed
Graphic LayerGraphic Layer C - Required if Graphic Annotation or Overlays or Curves are to be appliedC - Required if Graphic Annotation or Overlays or Curves are to be applied
SOP CommonSOP Common MM
GSPS Module Table:GSPS Module Table:
DICOM Grayscale Image DICOM Grayscale Image Transformation ModelTransformation Model
Trans formation
VOI LUT(Subtrac t ion)
Mas kModality
LUT
Trans formation
Annotat ion
Image
Trans format ion
Shutter Spat ia lTrans format ion
Annotat ion
Disp. Area
Presentation LUT
Presentation LUT
Transformation
Window/Levelor VOI LUT
Rescale Slope/Interceptor Modality LUT
OriginalImage
DisplayP-Values
Grayscale Transformations
Shutter, Annotation and Spatial Transformations
What about color ?What about color ?
Consistency is harder to achieveConsistency is harder to achieve– Not just colorimetry (i.e. not just CIELAB)Not just colorimetry (i.e. not just CIELAB)– Gamut of devices much more variableGamut of devices much more variable– Greater influence of psychovisual effectsGreater influence of psychovisual effects
Extensive standards efforts e.g. ICCExtensive standards efforts e.g. ICC DICOM is defining color presentation in a manner DICOM is defining color presentation in a manner
very similar to grayscale, but utilizing the ICC very similar to grayscale, but utilizing the ICC profiles instead of the GSDF, see Supplement 100.profiles instead of the GSDF, see Supplement 100.– Many display and print devices already have ICC Many display and print devices already have ICC
profiles, but few medical imaging devices support color profiles, but few medical imaging devices support color presentation state.presentation state.
Consistent Presentation is Consistent Presentation is Provided byProvided by
Use of DICOM GSDF for calibration of monitorsUse of DICOM GSDF for calibration of monitors Use of Presentation LUT for Grayscale PrintUse of Presentation LUT for Grayscale Print Creation of GSPS SOP Instances to capture the Creation of GSPS SOP Instances to capture the
presentation of softcopy images.presentation of softcopy images. Use of GSPS SOP Instances when displaying Use of GSPS SOP Instances when displaying
images from archivesimages from archives
( Devices that claim conformance to ( Devices that claim conformance to IHE Consistent Presentation of ImagesIHE Consistent Presentation of Imagesprovide these functions. )provide these functions. )