Consistent Presentation of Images Lawrence Tarbox, Ph.D. Washington University in St. Louis

Overview Review of Grayscale Presentation State Color Presentation States Color Consistency Presentation States applied to Color Images Color Blending - CT-PET fusion Hanging Protocols

Problems of Inconsistency VOI chosen on one display device Rendered on another with different display Mass expected to be seen is no longer seen mass visible mass invisible 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 Slide Provided by David Clunie, Quintiles Intelligent Imaging

Problems of Inconsistency Laser Printer Digital Modality Printed images don’t look like displayed images Slide Provided by David Clunie, Quintiles Intelligent Imaging

Grayscale Standard Display Function .01 .1 1 10 100 1000 200 400 600 800 Grayscale Standard Display Function JND Index Same number of Just Noticeable Difference == Same perceived contrast Despite different change in absolute luminance Slide Provided by David Clunie, Quintiles Intelligent Imaging

Display Calibration Tools (Photometer) Slide Provided by Jerry Gaskill, Image Smiths Inc.

Monitor Characteristic Curve Luminance 100 10 0.1 Ambient Light 0.01 50 100 150 200 250 300 Digital Driving Level Slide Provided by David Clunie, Quintiles Intelligent Imaging

Perceptual linear device - LUT Mapping P-Values to Input of Characteristic Curve (DDL’s) 50 100 150 200 250 300 P-Values DDL Slide Provided by David Clunie, Quintiles Intelligent Imaging

Grayscale Standard Display Function .01 .1 1 10 100 1000 200 400 600 800 Grayscale Standard Display Function JND Index Same number of Just Noticeable Difference == Same perceived contrast Despite different change in absolute luminance Slide Provided by David Clunie, Quintiles Intelligent Imaging

Distributed Image Consistency Laser Printer Digital Modality Identical perceived contrast Workstation Workstation

DICOM Grayscale Image Transformation Model V O I L U ( S u b c ) M k d l y A g e h p D . Presentation LUT Transformation Window/Level or VOI LUT Rescale Slope/Intercept or Modality LUT Original Image Display P-Values Grayscale Transformations Shutter, Annotation and Spatial Transformations Presentation LUT shape : IDENTITY, INVERSE 10

Spatial Transformations Entire Image Selected Flip Horizontal Scale To Fit Original Image Transformed Image

Spatial Transformations Part of Image Selected Flip Horizontal Scale To Fit Original Image Transformed Image

Transformation & Annotation Part of Image Selected Flip Horizontal Scale To Fit Mass behind heart Mass behind heart Original Image Transformed Image In this example, - text annotation is specified by image relative visible anchor point - the circle is a separate image relative graphic annotation

Distributed Image Consistency Printer Digital Modality Different perceived color Workstation Workstation

Distributed Image Consistency Printer Digital Modality Identical perceived color Workstation Workstation

Standard Color Space GSDF filled a void Color consistency already standardized ICC - International Color Consortium Graphics and pre-press industry CIE Colorimetry Profiles of input and output devices COTS color management software handles conversion Perceptual rendering intent

DICOM Grayscale Image Transformation Model V O I L U ( S u b c ) M k d l y A g e h p D . Presentation LUT Transformation Window/Level or VOI LUT Rescale Slope/Intercept or Modality LUT Original Image Display P-Values Grayscale Transformations Shutter, Annotation and Spatial Transformations Presentation LUT shape : IDENTITY, INVERSE 10

Grayscale & Color Pipeline

Blending for CT-PET select underlying select superimposed

Blending for CT-PET select underlying [register] select superimposed

Blending for CT-PET select underlying [register] select superimposed resample

Blending for CT-PET select underlying [register] within slices select superimposed resample

Blending for CT-PET select underlying [register] within slices select superimposed resample [between slices]

Blending for CT-PET select underlying rescale and window [register] within slices select superimposed resample [between slices]

Blending for CT-PET select underlying rescale and window [register] within slices select superimposed resample pseudo-color [between slices]

Blending for CT-PET select underlying rescale and window [register] within slices select superimposed resample pseudo-color [between slices]

Three New SOP Classes Color Presentation State Pseudo-Color Presentation State Blending Presentation State ICC Profile Defines output of all color presentation states Optionally present in all color images PCS-Values (analogous to grayscale P-Values) Profile Connection Space (CIELAB or CIEXYZ)

Hanging Protocols

Hanging Protocols “Default display protocols” A set of instructions How to layout a class of images for display Order, orientation, windowing, processing Not specific to a particular patient’s images Hence a protocol, not a presentation state

Hanging Protocols New Study Old Lateral New Frontal Townes L F Old Study

Using a Hanging Protocol Given a current exam (e.g. reading worklist) Find potentially applicable protocols Retrieve them from archive Select one from those available Select image +/- other studies to which it applies Display selected images as instructed