1. Soft Copy Presentation State
Herman Oosterwijk,
OTech Inc.
PACS and DICOM
training and consulting

2. Scenario:
Radiologist:

3. Radiologist:
Suspect
Suspected
area

4. Radiologist:
Physician:
Suspect
Suspected
area

5. Grayscale Softcopy Presentation State Storage:
1. Accommodate conversion of Pixels to Presentation values (P-values)
Note: P-values are device independent values (defined by Grayscale Standard Display Function).
2. Preserve additional transformations, annotations, shutter, spatial xforms 7

6. Softcopy Presentation State:
- Separation of Stored Image Instances from Display characteristics and changes
Presn param: WW, Ctr, rescl, intc.
Pres State
Composite Image Object
n : m
Presn param: WW, Ctr, rescl, intc.
Presn param: WW, Ctr, rescl, intc.
Image Object 8

7. Softcopy Presentation State:
- Separation of Images and Pres states (ctd)
Examples:
Zoom applied to multiple CT slices (e.g. Spine)
Double Window Width/Ctr for CT chest
Separate Overlays that generated by CAD
Reduction of data transfer and storage because
only one instance needed of image data 8

8. Softcopy Presentation State:
Important: Softcopy Presentation State contains parameters that are present in the image as well (e.g. WW/level):
Presentation State values/operations overrides the values in the image
If no values in Presentation State for particular operation than identity transformation
Photometric Interpretation (0028,0004) shall be ignored in Image 12

9. Softcopy Presentation State:
Image
Pres State
Modality LUT
Mask
VOI LUT
Presentation LUT
Overlays, Curves
Modality LUT
Mask
VOI LUT
Presentation LUT
Overlays, Curves
Shutters
Img Annotation
Spatial Xform
Displ Area Annotn
Ptr. 13

10. Softcopy Presentation State:
Composite object containing the presentation state parameters
Link this Composite object to one or more images (Series, filters); stored using same Study Instance UID (same Storage SOP Class!)
Communicate with regular Storage service (C_Store); Retrieve with Query/Retrieve service
Pres State SOP Instances are immutable: changes require a new SOP Inst UID
Note: generation and applying (selection) of pres states (SCU and SCP) outside scope of DICOM 9

11. Softcopy Pres. State: Image pipeline/ I n t r M d i y L U T
Presentation
LUT W i n d o w / L e v l r V O I U T M o d a l i t y L U T r n s f m ( S u b t r a c i o n ) M s k T r a n s f o m t i V O I L U
Presentation
LUT
Transformation O r i g n a l I m e e T r a n s f o m t i S h u e A n o t a i I m g e S p a t i l T r n s f o m A n o t a i D s p . r e P - V a l u e s D i s p l a y 10

12. Softcopy Pres. State: Image pipeline/ I n t r M d i y L U T
Presentation
LUT W i n d o w / L e v l r V O I U T M o d a l i t y L U T r n s f m ( S u b t r a c i o n ) M s k T r a n s f o m t i V O I L U
Presentation
LUT
Transformation O r i g n a l I m e e 10

13. Softcopy Presentation State:
Shutter
Image
Spatial
Disp. Area
P-Values
Display
Transformation
Transformation
Annotation
Annotation
look
Flip,
Rotate,
Zoom,
Pan
Text,
independent
from spatial
transformation 11

14. Softcopy Presentation State Module Table:

15. Patient, Study, Series module as well as SOP Common makes this a composite object
Presentation Series specializes Modality (0008,0060) of Gnl. Series Module: “PR”

16. Modules vs Pipeline: MASK VOI LUT PRES LUT SHUTR IMG ANN MOD LUT SPATL
XFORM
DISPL
ANN
IMAGE

17. Presentation State Module:
To identify the Pres. State object:
Instance (aka Image) number
Label, description, creation date/time, and creator’s name
Applies to which images: Ref series/image sequence
Misc:
Shutter presentation value (P-values)
Mask subtraction (average-time delay) 14

18. Modality LUT Module: Manufacturer values to modality pixel values
MASK
VOI
LUT
PRES
LUT
MOD
LUT
Manufacturer values to
modality pixel values
(Hounsfield, OD); LUT OR Rescale Slope/Interc.
- Modality LUT:
LUT Descriptor:
Number of entries in table
First stored pixel value mapped
Number of bits for each entry in LUT data
Modality LUT Type: output units (OD, US)
LUT data
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn 14

19. Modality LUT Module: Mod LUT: Output LUT: Unsigned
MASK
VOI
LUT
PRES
LUT
MOD
LUT
Mod LUT:
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn
Output
LUT:
Unsigned
Number of entries in LUT;
Number of bits for each entry:
(8 or 16)---> range is 256 or 65536
Data range
First Stored Pixel (FSP) value mapped (VR is defined by Pix.Repres.) 14

20. Modality LUT Module: Rescale Slope Intercept: Linear: Slope/ Intercept
MASK
MOD
LUT
VOI
LUT
PRES
LUT
Rescale Slope Intercept:
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn
Linear:
Slope/
Intercept
Example:
shift linear 2048
output values
Input values 14

21. Modality LUT Module: Issues/notes: Provides Mod LUT for
MASK
MOD
LUT
VOI
LUT
PRES
LUT
Issues/notes:
Provides Mod LUT for
CT (is normally not part of CT Image IOD)
Output range depends on whether Mod Lut is used or rescale/Intercept:
Unsigned for Mod LUT
Defined by value of rescale slope/Intercept and Pixel representation; could be signed even if Pixel representation is unsigned
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn 14

22. MASK Module: Mask operation: Subtract frames with fixed
LUT
VOI
LUT
PRES
LUT
MASK
Mask operation:
Subtract frames with fixed
position or time interval:
AVG_SUB; Average subtraction:
Average frames identified by MASK Frame Numbers, shift by MASK Sub-Pixel Shift and subtract from frames Applicable Frame Range
TID; Time Interval differencing:
Subtract TID Offset from frame number to select the mask to be subtracted
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn 14

23. MASK Module: Issues/Notes:
LUT
VOI
LUT
PRES
LUT
MASK
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn
Issues/Notes:
For X-ray images, subtraction needs to be in log space relative to X-ray intensity; could be done by applying Mod LUT (if so needed)
Output is signed value, one bit longer than source frames 14

24. VOI LUT Module: Map modality pixel values (Hounsfield) to application
PRES
LUT
MASK
VOI
LUT
Map modality pixel values
(Hounsfield) to application
significant values: VOI LUT or WW/Center
- VOI LUT:
LUT Descriptor:
Number of entries in table
First input value mapped
Number of bits for each entry in LUT data
LUT data
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn 14

25. VOI LUT Module: Window Width/Center: (is better defined!) width
PRES
LUT
MASK
VOI
LUT
Window Width/Center:
(is better defined!)
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn
width
output values
center
Input values 14

26. VOI LUT Module: WW/Ctr Issues/Notes: Assume floating point
PRES
LUT
MASK
VOI
LUT
WW/Ctr Issues/Notes:
Assume floating point
calculation:
WW 1, Ctr 0: <= value <= 0.5
WW 100, Ctr 0: -50 <= value <= +50
WW 4095, Ctr 2047: -0.5 <= value <=
Selected input range may exceed actual input range: image will be “flattened”
Output is scaled to display device OR to range of Pres LUT
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn 14

27. VOI LUT Module: Issues/Notes: Photometric Interpret. Is ignored
PRES
LUT
MASK
VOI
LUT
Issues/Notes:
Photometric Interpret.
Is ignored
VOI LUT can have sections with negative slope
Image VOI LUT shall not be used
Only a single VOI LUT shall be present (multiple requires different Pres States); this is not the case for the VOI Lut’s as present in the images (can be multiple)
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn 14

28. SC Pres. LUT Module: Pixels to P-values: (assumes Grayscale
MASK
VOI
LUT
PRES
LUT
Pixels to P-values:
(assumes Grayscale
Display Function standard)
LUT Descriptor:
Number of entries in table
First input value mapped (always scaled to 0)
Number of bits for each entry in LUT data
LUT data
Pres LUT shape; reqd if no LUT
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn 14

29. SC Pres LUT Module: LUT maps full range Output LUT: Unsigned
MASK
VOI
LUT
PRES
LUT
MOD
LUT
LUT maps full range
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn
Output
LUT:
Unsigned
Number of entries in LUT;
Number of bits for each entry:
(8<=n<=16)
Data range
First Stored Pixel (FSP) value mapped; scaled to 0 (VR is US) 14

30. SC Pres. LUT Module: Issues/Notes:
MASK
VOI
LUT
PRES
LUT
Issues/Notes:
If no Pres LUT and VOI LUT, Mod LUT has to make sure that output is in P-values
LUT Shape might reflect Monochrome 1/2 in case not reflected in the pipeline before (IDENTITY-INVERSE)
No separate polarity inversion is defined
Pres LUT is Required (M); xform could be “Identity”
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn 14

31. VR at different stages:
MOD
LUT
MASK
VOI
LUT
PRES
LUT
Pix data
[Pix Repres]
P-values
Ident US
MOD
LUT
VOI
LUT US US
SC Pr
LUT US
MASK
RSC/
INT
WW/
Ctr
SS/US
SS/US 14

32. Shutter XForm: Two modules: Display shutter module:
LUT
MASK
VOI
LUT
PRES
LUT
Two modules:
Display shutter module:
Shape: Rectangular, Circular, Polygonal
Coordinates (edge, ctr, radius, vertices)
optional Presentation (padding) Value
Bitmap Display Shutter Module:
Shape (bitmap)
Overlay group [60xx] (in Pres State Object!)
reqd Presentation (padding) Value
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn 14

33. Image Annotation: Pre-spatial xform annotation (e.g. ROI shapes)
MOD
LUT
MASK
VOI
LUT
PRES
LUT
Pre-spatial xform annotation
(e.g. ROI shapes)
Use Overlay/Curve
Activation Module:
If Curve activated, only curve contained in images are activated (curves are replaced by Graphic Annotation Module in SC Pres State)
If Overlay activated, could be in Image or SC Pres State object
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn 14

34. Image Annotation: Graphic Layer: Groups related graphics,
MOD
LUT
MASK
VOI
LUT
PRES
LUT
Graphic Layer:
Groups related graphics,
identifies with text string, provides order number and display value (incl color) as well as free text description
Referenced from the Graphic annotation module
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn 14

35. Image Annotation: Graphic Ann. Module: - Graphics, text or both
LUT
MASK
VOI
LUT
PRES
LUT
Graphic Ann. Module:
- Graphics, text or both
Bounding box OR Anchor points units: “Pixel”
Types are Polyline, Interpolated, Circle or Elipse
Graphic could be filled
Addressing: Pixel 1\1 is in between Point (0.0\0.0) and Point (1.0\1.0)
Shttr
Spatl
Xform
Img
Anntn
Displ
Anntn 14

36. Image Annotation: Graphic Ann. Module: - Issues/Notes:
LUT
MASK
VOI
LUT
PRES
LUT
Graphic Ann. Module:
- Issues/Notes:
Text could be outside bounding box
Text could be in scrolling box or link to other window
Transparency, opacity or “exclusive or” of bounding box is implementation specific
“Anchor Point visibility” determines line or arrow from point to text; text might be repositioned as appropriate for zoom
Shttr
Spatl
Xform
Img
Anntn
Displ
Anntn 14

37. Spatial Xform: Rotate, Flip, Minify/Zoom and region selection:
MOD
LUT
MASK
VOI
LUT
PRES
LUT
Rotate, Flip, Minify/Zoom
and region selection:
Spatial Xform module:
Rotate (0, 90, 180, 270) CW
Horizontal flip
Displayed area module:
Top Left hand Corner and Bottom Right Hand Corner of data to be displayed relative to pixel data (1\1)
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn 14

38. Spatial Xform: Displayed area module: (1\1) TLHC BRHC (Rows\columns)
LUT
MASK
VOI
LUT
PRES
LUT
Displayed area module:
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn
(1\1)
TLHC
BRHC
(Rows\columns) 14

39. Spatial Xform: Notes/Issues: Area can be greater than
MOD
LUT
MASK
VOI
LUT
PRES
LUT
Notes/Issues:
Area can be greater than
result from spatial transformation (e.g. a 1200 by 1000 display displaying a 1k by 1k image)
Result shall be displayed as large as possible within display area (magnified if applicable)
Minification is achieved by a negative TLHC and/or BRHC greater than Rows or Columns
Rotate/Flip applied BEFORE zoom/minify
Shttr
Img
Anntn
Spatl
Xform
Displ
Anntn 14

40. Displ. Area Annotation:
MOD
LUT
MASK
VOI
LUT
PRES
LUT
Display dependent
graphics
Graphic Ann. Module: Graphics, text or both
Bounding box OR Anchor points units: “DISPLAY”
Types are Polyline, Interpolated, Circle or Elipse
Graphic could be filled
Addressing: Pixel 1\1 is in between Point (0.0\0.0) and Point (1.0\1.0)
Shttr
Spatl
Xform
Img
Anntn
Displ
Anntn 14

41. Softcopy Presentation State Conformance Statement requirements:
SCU:
How are presentation attributes derived from Image, operator intervention, defaults
How is info included in IOD
Which Image Storage SOP classes are supported and can be referenced by the SC Presentation State 14

42. Softcopy Presentation State Conformance Statement requirements (ctd):
SCP:
How are attributes used to influence image display
Which Image Storage SOP classes are supported and may be referenced by the Sofcopy presentation State 14

43. Softcopy Presentation State media extensions:
Directory Type added “Presentation”
Included below Series Directory record entry
Can be stored on a general purpose CD-R 14

44. Status Softcopy Presentation State supplement:
Draft for trial implementation
Demonstration/implementation funded by DICOM committee at ECR, March ‘99
Main contractor OTech, proj. Mgt. lake Grifin, implementation by OFFIS (U Oldenburgh) and Microtherapy (U Witten/herdecke)
Main sponsors are Imation, Philips, Siemens, GE and ISG; Image Smiths provides calibration
Software will be in available in public domain 14

45. Goals Softcopy Presentation State demo:
Education of user community and sollicitation of feedback
Demonstration of this specific supplement
Promotion of early implementation and adoption
Modality simulator
Diagn workstation
Physician workstation 14

46. Softcopy Presentation State does NOT (yet) address:
- Color (no Color Display function)
- No screen layout issues are addressed, including size of images on screen
- No query of display characteristics (like Print configuration)
- No 3D display and/or image fusion (CT/MR/NM) 14

47. Softcopy Presentation State provides:
Image Presentation consistency (vs grayscale consistency defined by Grayscale function)
Tighter definition of presentation parameters (WW/Ctr, etc)
Uncoupling of presentation and images; eliminates multiple instances of images with same pixel data
Address exchange of overlays and text (currently often solved with proprietary means) 14

48. (Print) Presentation LUT:
Relates to Image Box, Film Box or Film Session
Normalized IOD:
Presentation LUT Module:
LUT descriptor
Explanation
LUT data
LUT Shape: IDENTITY or LIN OD (range is Min density to max density) 14

49. DICOM Presentation LUT
GOAL: Consistent image quality.
Transformation of pixel values into P-values
For hardcopy, P-values are transformed into optical density
Image display can be tailored for specific modalities, applications and user preferences