Digital Hologram Image Processing<br />(DHIP)<br />Conor Mc Elhinney<br />Wednesday 13th May<br />Contact: conormce@cs.nui...
Why digital holography?<br />Using digital holography we can record a scene in a complex valued data structure which retai...
Why digital holography?<br />Yves Gevant Ultimate Hologram<br />http://www.ultimate-holography.com<br />Contact: conormce@...
Image Processing<br />Image processing attempts to “understand” a scene through the analysis of one recorded image or a se...
How can we use this extra information in a hologram<br />In the early days we took a look around to see what was being att...
How can we use this extra information in a hologram<br />In the early days we took a look around to see what was being att...
How can we use this extra information in a hologram<br />In the early days we took a look around to see what was being att...
Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />Contact: ...
Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />What info...
Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />What info...
Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />What info...
Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />What info...
Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />What info...
Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />What info...
Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />What info...
Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />Combined ...
To be generally applicable..<br />We also wanted our algorithms to be useful to as many forms of holography as possible.<b...
What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What ha...
What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What ha...
What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What ha...
What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What ha...
What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What ha...
What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What ha...
What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What ha...
What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What ha...
What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What ha...
What I’ve done<br />What is a digital hologram? Twin-images / dc-term/...<br />How does holography work?<br />What have ot...
Digital reconstruction<br />Just some quick examples and reminders of what is in a reconstruction.<br />Contact: conormce@...
DC-term suppression<br />Taking a single hologram prior to any processing, we reconstruct this to demonstrate the corrupti...
DC-term suppression<br />Taking a single hologram prior to any processing, we reconstruct this to demonstrate the corrupti...
DC-term suppression<br />Hologram<br />Reconstruction<br />Contact: conormce@cs.nuim.ie<br />
DC-term suppression<br />Hologram<br />Fourier<br />transform<br />Contact: conormce@cs.nuim.ie<br />
DC-term suppression<br />Hologram<br />Fourier<br />transform<br />High-pass<br />Filter<br />Contact: conormce@cs.nuim.ie...
DC-term suppression<br />Hologram<br />DC-Free Hologram<br />Inverse<br />Fourier<br />transform<br />Fourier<br />transfo...
DC-term suppression<br />Hologram<br />DC-Free Hologram<br />Inverse<br />Fourier<br />transform<br />Fourier<br />transfo...
DC-term suppression<br />Hologram<br />DC-Free Hologram<br />Inverse<br />Fourier<br />transform<br />Fourier<br />transfo...
DC-term suppression example<br />Contact: conormce@cs.nuim.ie<br />
Shallow depth-of-field<br />Reconstructions from digital holograms have a shallow depth of field, sometimes as small as 1m...
Shallow depth-of-field<br />Reconstructions from digital holograms have a shallow depth of field, sometimes as small as 1m...
Focusing a digital hologram<br />Contact: conormce@cs.nuim.ie<br />
Using a window to reconstruct<br />Contact: conormce@cs.nuim.ie<br />
Perspectives and digital holography<br />So we first select a window from within the hologram plane (we also need to know ...
Perspectives and digital holography<br />So we first select a window from within the hologram plane (we also need to know ...
How to we reconstruct a perspective<br />We select a window size from within the hologram.<br />Win Size<br />Contact: con...
How to we reconstruct a perspective<br />We select a window size from within the hologram.<br />As we have already seen th...
How to we reconstruct a perspective<br />We select a window size from within the hologram.<br />There is a trade-off betwe...
What angle are we reconstructing?<br />So we first select a window from within the hologram plane (we also need to know th...
What angle are we reconstructing?<br />So we first select a window from within the hologram plane (we also need to know th...
What angle are we reconstructing?<br />We then work out how far we want to offset this window from the centre of the holog...
What angle are we reconstructing?<br />The angle we are reconstructing can then be worked out with trigonometry.<br />Holo...
What angle are we reconstructing?<br />The angle we are reconstructing can then be worked out with trigonometry.<br />Holo...
What angle are we reconstructing?<br />The angle we are reconstructing can then be worked out with trigonometry.<br />Holo...
What perspective are we reconstructing<br />Nx<br />y<br />Nx’<br />Ny<br />ay<br />Ny’<br />x<br />ax<br />z<br />d<br />...
Perspective reconstruction<br />Contact: conormce@cs.nuim.ie<br />
How does speckle reduction effect the reconstruction<br />Contact: conormce@cs.nuim.ie<br />
Simple linear autofocus<br />Contact: conormce@cs.nuim.ie<br />
Examples of what we’ve done<br />Automatically determining the focal plane of a digital hologram using a Fibonacci search<...
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Search Range: [170mm,..............................................................
Autofocus - Fibonacci search example<br />Displayed in the plot is the first 8 estimates output from Fibonacci (both corre...
Depth from focus decisions	<br />Two of the primary decisions in depth-from-focus are:<br />What block size to use?<br />W...
Block Size<br /> To determine the depth of a block in an image using a focus measure there needs to be enough object infor...
Block Size<br />Contact: conormce@cs.nuim.ie<br />
Distance between reconstructions<br />By changing the distance between reconstructions we affect the quality of the depth ...
Distance between reconstructions<br />By changing the distance between reconstructions we affect the quality of the depth ...
Depth segmentation and the reconstruction interval<br />First we are going to look at the two bolts object and segmenting ...
Two bolts - 4 segments<br />0.1mm<br />Contact: conormce@cs.nuim.ie<br />
Two bolts - 4 segments<br />0.2mm<br />Contact: conormce@cs.nuim.ie<br />
Two bolts - 4 segments<br />0.5mm<br />Contact: conormce@cs.nuim.ie<br />
Two bolts - 4 segments<br />1mm<br />Contact: conormce@cs.nuim.ie<br />
Two bolts - 4 segments<br />2mm<br />Contact: conormce@cs.nuim.ie<br />
Depth segmentation and the reconstruction interval<br />Now we will see if we can segment it into 8 regions<br />Contact: ...
Two bolts - 8 segments<br />0.1mm<br />Contact: conormce@cs.nuim.ie<br />
Two bolts - 8 segments<br />0.1mm<br />Contact: conormce@cs.nuim.ie<br />
Two bolts - 8 segments<br />0.5mm<br />Contact: conormce@cs.nuim.ie<br />
Two bolts - 8 segments<br />1mm<br />Contact: conormce@cs.nuim.ie<br />
Two bolts - 8 segments<br />2mm<br />??<br />Contact: conormce@cs.nuim.ie<br />
Twin-image<br />A hologram contains a set of twin-images.<br />One at the positive distance and one at the negative.<br />...
Results – Rotating object<br />Contact: conormce@cs.nuim.ie<br />
Results – Rotating object<br />Questions??<br />Contact: conormce@cs.nuim.ie<br />
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Digital Hologram Image Processing

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Digital Hologram Image Processing

  1. 1. Digital Hologram Image Processing<br />(DHIP)<br />Conor Mc Elhinney<br />Wednesday 13th May<br />Contact: conormce@cs.nuim.ie<br />
  2. 2. Why digital holography?<br />Using digital holography we can record a scene in a complex valued data structure which retains some of the scene's 3D information. A standard image obtained with a camera records a 2D focused image of the scene from one perspective.<br />Contact: conormce@cs.nuim.ie<br />
  3. 3. Why digital holography?<br />Yves Gevant Ultimate Hologram<br />http://www.ultimate-holography.com<br />Contact: conormce@cs.nuim.ie<br />
  4. 4. Image Processing<br />Image processing attempts to “understand” a scene through the analysis of one recorded image or a sequence of recorded images of the scene. <br />Typical questions it tries to answer are:<br />What is important in the scene?<br />How many relevant objects are in the scene?<br />Where are they in the scene?<br />What do they look like?<br />What are they?<br />In standard image processing each recorded image is a 2D focused image of the scene.<br />We wanted to apply image processing to digital holograms where each reconstruction is a 2D focused image of the scene. <br />Contact: conormce@cs.nuim.ie<br />
  5. 5. How can we use this extra information in a hologram<br />In the early days we took a look around to see what was being attempted in digital holography and what had and hadn’t been solved<br />Microscopic<br />Macroscopic<br />Autofocus – Some Proposed solutions<br />Shape Estimation – Phase unwrapping<br />Segmentation - ?<br />Autofocus – Some Proposed solutions<br />Shape Estimation – Ma depth extraction just proposed<br />Segmentation - ?<br />Contact: conormce@cs.nuim.ie<br />
  6. 6. How can we use this extra information in a hologram<br />In the early days we took a look around to see what was being attempted in digital holography and what had and hadn’t been solved<br />Microscopic<br />Macroscopic<br />In-Line<br />In-Line<br />Autofocus – Some Proposed solutions<br />Shape Estimation – Phase unwrapping<br />Segmentation - ?<br />Twin-Image - ?<br />Autofocus – Some Proposed solutions<br />Shape Estimation – Ma depth extraction just proposed<br />Segmentation - ?<br />Twin-Image - ?<br />Contact: conormce@cs.nuim.ie<br />
  7. 7. How can we use this extra information in a hologram<br />In the early days we took a look around to see what was being attempted in digital holography and what had and hadn’t been solved<br />We saw a lack of research in the processing of single capture in-line macroscopic digital holograms<br />Microscopic<br />Macroscopic<br />In-Line<br />In-Line<br />Autofocus – Some Proposed solutions<br />Shape Estimation – Phase unwrapping<br />Segmentation - ?<br />Twin-Image - ?<br />Autofocus – Some Proposed solutions<br />Shape Estimation – Ma depth extraction just proposed<br />Segmentation - ?<br />Twin-Image - ?<br />Contact: conormce@cs.nuim.ie<br />
  8. 8. Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />Contact: conormce@cs.nuim.ie<br />
  9. 9. Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />What information is in the scene?<br />Contact: conormce@cs.nuim.ie<br />
  10. 10. Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />What information is in the scene?<br />Contact: conormce@cs.nuim.ie<br />
  11. 11. Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />What information is in the scene?<br />Where is this information?<br />+<br />Contact: conormce@cs.nuim.ie<br />
  12. 12. Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />What information is in the scene?<br />Where is this information?<br />+<br />Contact: conormce@cs.nuim.ie<br />
  13. 13. Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />What information is in the scene?<br />Where is this information?<br />What does it look like?<br />+<br />+<br />Contact: conormce@cs.nuim.ie<br />
  14. 14. Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />What information is in the scene?<br />Where is this information?<br />What does it look like?<br />What is it?<br />+<br />+<br />+<br />Contact: conormce@cs.nuim.ie<br />
  15. 15. Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />What information is in the scene?<br />Where is this information?<br />What does it look like?<br />What is it?<br />+<br />+<br />+<br />Object 1<br />Object 2<br />Contact: conormce@cs.nuim.ie<br />
  16. 16. Our noble goal<br />So we started out wanting to develop ways of “understanding” what is in a hologram.....<br />Combined this helps us “understand” the scene<br />What information is in the scene?<br />Where is this information?<br />What does it look like?<br />What is it?<br />+<br />+<br />+<br />Object 1<br />Object 2<br />Contact: conormce@cs.nuim.ie<br />
  17. 17. To be generally applicable..<br />We also wanted our algorithms to be useful to as many forms of holography as possible.<br />So each function or algorithm should be modular, i.e<br />Depth segmentation requires a depth map as input which could be an unwrapped phase map from digital holographic microscopy.<br />Contact: conormce@cs.nuim.ie<br />
  18. 18. What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What have others done in macroscopic DH?<br />How to focus a DH?<br />How to get depth info?<br />Segmenting based on focus info<br />Create an in-focus image from depth/intensity<br />Segmenting based on depth info<br />How do we focus fast?<br />Segment and remove the twin<br />Contact: conormce@cs.nuim.ie<br />
  19. 19. What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What have others done in macroscopic DH?<br />How to focus a DH?<br />How to get depth info?<br />Segmenting based on focus info<br />Create an in-focus image from depth/intensity<br />Segmenting based on depth info<br />How do we focus fast?<br />Segment and remove the twin<br />Contact: conormce@cs.nuim.ie<br />
  20. 20. What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What have others done in macroscopic DH?<br />How to focus a DH?<br />How to get depth info?<br />Segmenting based on focus info<br />Create an in-focus image from depth/intensity<br />Segmenting based on depth info<br />How do we focus fast?<br />Segment and remove the twin<br />Contact: conormce@cs.nuim.ie<br />
  21. 21. What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What have others done in macroscopic DH?<br />How to focus a DH?<br />How to get depth info?<br />Segmenting based on focus info<br />Create an in-focus image from depth/intensity<br />Segmenting based on depth info<br />How do we focus fast?<br />Segment and remove the twin<br />Contact: conormce@cs.nuim.ie<br />
  22. 22. What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What have others done in macroscopic DH?<br />How to focus a DH?<br />How to get depth info?<br />Segmenting based on focus info<br />Create an in-focus image from depth/intensity<br />Segmenting based on depth info<br />How do we focus fast?<br />Segment and remove the twin<br />Contact: conormce@cs.nuim.ie<br />
  23. 23. What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What have others done in macroscopic DH?<br />How to focus a DH?<br />How to get depth info?<br />Segmenting based on focus info<br />Create an in-focus image from depth/intensity<br />Segmenting based on depth info<br />How do we focus fast?<br />Segment and remove the twin<br />Contact: conormce@cs.nuim.ie<br />
  24. 24. What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What have others done in macroscopic DH?<br />How to focus a DH?<br />How to get depth info?<br />Segmenting based on focus info<br />Create an in-focus image from depth/intensity<br />Segmenting based on depth info<br />How do we focus fast?<br />Segment and remove the twin<br />Contact: conormce@cs.nuim.ie<br />
  25. 25. What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What have others done in macroscopic DH?<br />How to focus a DH?<br />How to get depth info?<br />Segmenting based on focus info<br />Create an in-focus image from depth/intensity<br />Segmenting based on depth info<br />How do we focus fast?<br />Segment and remove the twin<br />Contact: conormce@cs.nuim.ie<br />
  26. 26. What I’ve done<br />What is a digital hologram?<br />Twin-images / dc-term/...<br />How does holography work?<br />What have others done in macroscopic DH?<br />How to focus a DH?<br />How to get depth info?<br />Segmenting based on focus info<br />Create an in-focus image from depth/intensity<br />Segmenting based on depth info<br />How do we focus fast?<br />Segment and remove the twin<br />Contact: conormce@cs.nuim.ie<br />
  27. 27. What I’ve done<br />What is a digital hologram? Twin-images / dc-term/...<br />How does holography work?<br />What have others done in macroscopic DH?<br />How to focus a DH?<br />How to get depth info?<br />Segmenting based on focus info<br />Create an in-focus image from depth/intensity<br />Segmenting based on depth info<br />How do we focus fast?<br />Segment and remove the twin<br />Contact: conormce@cs.nuim.ie<br />
  28. 28. Digital reconstruction<br />Just some quick examples and reminders of what is in a reconstruction.<br />Contact: conormce@cs.nuim.ie<br />
  29. 29. DC-term suppression<br />Taking a single hologram prior to any processing, we reconstruct this to demonstrate the corruptive effect of the DC-term<br />365 mm<br />Reconstruction plane<br />Hologram<br />Reconstruct<br />Contact: conormce@cs.nuim.ie<br />
  30. 30. DC-term suppression<br />Taking a single hologram prior to any processing, we reconstruct this to demonstrate the corruptive effect of the DC-term<br />365 mm<br />Reconstruction plane<br />Hologram<br />Reconstruct<br />There are many methods for suppressing the DC-term, our twin-image removal algorithm takes as input a DC-term suppressed hologram. For our experiments we apply a high-pass filter in the Fourier domain to suppress the DC-term.<br />Contact: conormce@cs.nuim.ie<br />
  31. 31. DC-term suppression<br />Hologram<br />Reconstruction<br />Contact: conormce@cs.nuim.ie<br />
  32. 32. DC-term suppression<br />Hologram<br />Fourier<br />transform<br />Contact: conormce@cs.nuim.ie<br />
  33. 33. DC-term suppression<br />Hologram<br />Fourier<br />transform<br />High-pass<br />Filter<br />Contact: conormce@cs.nuim.ie<br />
  34. 34. DC-term suppression<br />Hologram<br />DC-Free Hologram<br />Inverse<br />Fourier<br />transform<br />Fourier<br />transform<br />High-pass<br />Filter<br />Contact: conormce@cs.nuim.ie<br />
  35. 35. DC-term suppression<br />Hologram<br />DC-Free Hologram<br />Inverse<br />Fourier<br />transform<br />Fourier<br />transform<br />High-pass<br />Filter<br />Reconstruction<br />Contact: conormce@cs.nuim.ie<br />
  36. 36. DC-term suppression<br />Hologram<br />DC-Free Hologram<br />Inverse<br />Fourier<br />transform<br />Fourier<br />transform<br />High-pass<br />Filter<br />Reconstruction<br />Reconstruction<br />Contact: conormce@cs.nuim.ie<br />
  37. 37. DC-term suppression example<br />Contact: conormce@cs.nuim.ie<br />
  38. 38. Shallow depth-of-field<br />Reconstructions from digital holograms have a shallow depth of field, sometimes as small as 1mm. This means that processing an individual reconstruction is rarely a good idea. <br />188mm<br />178mm<br />Contact: conormce@cs.nuim.ie<br />
  39. 39. Shallow depth-of-field<br />Reconstructions from digital holograms have a shallow depth of field, sometimes as small as 1mm. This means that processing an individual reconstruction is rarely a good idea. <br />188mm<br />178mm<br />Contact: conormce@cs.nuim.ie<br />
  40. 40. Focusing a digital hologram<br />Contact: conormce@cs.nuim.ie<br />
  41. 41. Using a window to reconstruct<br />Contact: conormce@cs.nuim.ie<br />
  42. 42. Perspectives and digital holography<br />So we first select a window from within the hologram plane (we also need to know the distance to the object).<br />Viewer<br />Display<br />Contact: conormce@cs.nuim.ie<br />
  43. 43. Perspectives and digital holography<br />So we first select a window from within the hologram plane (we also need to know the distance to the object).<br />Viewer<br />Display<br />Contact: conormce@cs.nuim.ie<br />
  44. 44. How to we reconstruct a perspective<br />We select a window size from within the hologram.<br />Win Size<br />Contact: conormce@cs.nuim.ie<br />
  45. 45. How to we reconstruct a perspective<br />We select a window size from within the hologram.<br />As we have already seen there is a trade-off between window size and visual quality.<br />Win Size<br />Contact: conormce@cs.nuim.ie<br />
  46. 46. How to we reconstruct a perspective<br />We select a window size from within the hologram.<br />There is a trade-off between window size and visual quality.<br />We then move the window from the centre of the hologram window.<br />Offset ax<br />Contact: conormce@cs.nuim.ie<br />
  47. 47. What angle are we reconstructing?<br />So we first select a window from within the hologram plane (we also need to know the distance to the object).<br />Hologram Plane<br />Near Object Plane<br />d<br />Optical Axis<br />Contact: conormce@cs.nuim.ie<br />
  48. 48. What angle are we reconstructing?<br />So we first select a window from within the hologram plane (we also need to know the distance to the object).<br />Hologram Plane<br />Near Object Plane<br />d<br />Optical Axis<br />Contact: conormce@cs.nuim.ie<br />
  49. 49. What angle are we reconstructing?<br />We then work out how far we want to offset this window from the centre of the hologram.<br />Hologram Plane<br />Near Object Plane<br />ax<br />d<br />Optical Axis<br />Contact: conormce@cs.nuim.ie<br />
  50. 50. What angle are we reconstructing?<br />The angle we are reconstructing can then be worked out with trigonometry.<br />Hologram Plane<br />Near Object Plane<br />ax<br />d<br />Optical Axis<br />Contact: conormce@cs.nuim.ie<br />
  51. 51. What angle are we reconstructing?<br />The angle we are reconstructing can then be worked out with trigonometry.<br />Hologram Plane<br />Near Object Plane<br />ax<br />θx<br />d<br />Optical Axis<br />Contact: conormce@cs.nuim.ie<br />
  52. 52. What angle are we reconstructing?<br />The angle we are reconstructing can then be worked out with trigonometry.<br />Hologram Plane<br />Near Object Plane<br />ax<br />θx<br />d<br />Optical Axis<br />Contact: conormce@cs.nuim.ie<br />
  53. 53. What perspective are we reconstructing<br />Nx<br />y<br />Nx’<br />Ny<br />ay<br />Ny’<br />x<br />ax<br />z<br />d<br />and<br />Contact: conormce@cs.nuim.ie<br />
  54. 54. Perspective reconstruction<br />Contact: conormce@cs.nuim.ie<br />
  55. 55. How does speckle reduction effect the reconstruction<br />Contact: conormce@cs.nuim.ie<br />
  56. 56. Simple linear autofocus<br />Contact: conormce@cs.nuim.ie<br />
  57. 57. Examples of what we’ve done<br />Automatically determining the focal plane of a digital hologram using a Fibonacci search<br />Contact: conormce@cs.nuim.ie<br />
  58. 58. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Choose our search range<br />Contact: conormce@cs.nuim.ie<br />
  59. 59. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Choose our search range<br />start<br />Contact: conormce@cs.nuim.ie<br />
  60. 60. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Choose our search range<br />end<br />Contact: conormce@cs.nuim.ie<br />
  61. 61. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Iteration 1:<br />Contact: conormce@cs.nuim.ie<br />
  62. 62. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Iteration 1:<br />487.03mm<br />Calculate our first <br />reconstruction distance<br />Contact: conormce@cs.nuim.ie<br />
  63. 63. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Iteration 1:<br />487.03mm<br />682.96mm<br />Calculate our second <br />reconstruction distance<br />Contact: conormce@cs.nuim.ie<br />
  64. 64. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Iteration 1:<br />487.03mm (26.5)<br />682.96mm (22.3)<br />Focus value for that distance<br />Contact: conormce@cs.nuim.ie<br />
  65. 65. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Iteration 1:<br />487.03mm (26.5)<br />682.96mm (22.3)<br />Red means current best estimate.<br />Contact: conormce@cs.nuim.ie<br />
  66. 66. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Iteration 1:<br />487.03mm (26.5)<br />682.96mm (22.3)<br />Iteration 2:<br />365.93mm (73.3)<br />Contact: conormce@cs.nuim.ie<br />
  67. 67. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Iteration 1:<br />487.03mm (26.5)<br />682.96mm (22.3)<br />Iteration 2:<br />365.93mm (73.3)<br />Iteration 3:<br />291.1mm (35.9)<br />Contact: conormce@cs.nuim.ie<br />
  68. 68. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Iteration 1:<br />487.03mm (26.5)<br />682.96mm (22.3)<br />Iteration 2:<br />365.93mm (73.3)<br />Iteration 3:<br />291.1mm (35.9)<br />412.20mm (44.8)<br />Iteration 4:<br />Contact: conormce@cs.nuim.ie<br />
  69. 69. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Iteration 1:<br />487.03mm (26.5)<br />682.96mm (22.3)<br />Iteration 2:<br />365.93mm (73.3)<br />Iteration 3:<br />291.1mm (35.9)<br />412.20mm (44.8)<br />Iteration 4:<br />Iteration 5:<br />337.35mm (66.6)<br />Contact: conormce@cs.nuim.ie<br />
  70. 70. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Iteration 1:<br />487.03mm (26.5)<br />682.96mm (22.3)<br />Iteration 2:<br />365.93mm (73.3)<br />Iteration 3:<br />291.1mm (35.9)<br />412.20mm (44.8)<br />Iteration 4:<br />Iteration 5:<br />337.35mm (66.6)<br />Iteration 6:<br />383.6mm (54.3)<br />Contact: conormce@cs.nuim.ie<br />
  71. 71. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Iteration 1:<br />487.03mm (26.5)<br />682.96mm (22.3)<br />Iteration 2:<br />365.93mm (73.3)<br />Iteration 3:<br />291.1mm (35.9)<br />412.20mm (44.8)<br />Iteration 4:<br />Iteration 5:<br />337.35mm (66.6)<br />Iteration 6:<br />383.6mm (54.3)<br />Iteration 7:<br />355.02mm (103.1)<br />Contact: conormce@cs.nuim.ie<br />
  72. 72. Autofocus - Fibonacci search example<br />Search Range: [170mm,............................................................................................., 1000mm]<br />Iteration 1:<br />487.03mm (26.5)<br />682.96mm (22.3)<br />Iteration 2:<br />365.93mm (73.3)<br />Iteration 3:<br />291.1mm (35.9)<br />412.20mm (44.8)<br />Iteration 4:<br />Iteration 5:<br />337.35mm (66.6)<br />Iteration 6:<br />383.6mm (54.3)<br />Iteration 7:<br />355.02mm (103.1)<br />...............<br />Iteration 14:<br />353.42mm (108.0)<br />Contact: conormce@cs.nuim.ie<br />
  73. 73. Autofocus - Fibonacci search example<br />Displayed in the plot is the first 8 estimates output from Fibonacci (both correct and incorrect) overlayed on the focus plot from the fixed step size search.<br />Contact: conormce@cs.nuim.ie<br />
  74. 74. Depth from focus decisions <br />Two of the primary decisions in depth-from-focus are:<br />What block size to use?<br />What interval between reconstructions to use?<br />Contact: conormce@cs.nuim.ie<br />
  75. 75. Block Size<br /> To determine the depth of a block in an image using a focus measure there needs to be enough object information in the block.<br />Smaller block sizes: finer object features but high error in the estimate of the general shape.<br />Larger block sizes: low error but fine object features lost.<br />Object<br />Contact: conormce@cs.nuim.ie<br />7x7<br />43x43<br />81x81<br />121x121<br />151x151<br />
  76. 76. Block Size<br />Contact: conormce@cs.nuim.ie<br />
  77. 77. Distance between reconstructions<br />By changing the distance between reconstructions we affect the quality of the depth maps. The smaller the distance the more features we can detect but at the expense of speed.<br />Contact: conormce@cs.nuim.ie<br />
  78. 78. Distance between reconstructions<br />By changing the distance between reconstructions we affect the quality of the depth maps. The smaller the distance the more features we can detect but at the expense of speed.<br />Contact: conormce@cs.nuim.ie<br />
  79. 79. Depth segmentation and the reconstruction interval<br />First we are going to look at the two bolts object and segmenting it into 4 regions<br />Contact: conormce@cs.nuim.ie<br />
  80. 80. Two bolts - 4 segments<br />0.1mm<br />Contact: conormce@cs.nuim.ie<br />
  81. 81. Two bolts - 4 segments<br />0.2mm<br />Contact: conormce@cs.nuim.ie<br />
  82. 82. Two bolts - 4 segments<br />0.5mm<br />Contact: conormce@cs.nuim.ie<br />
  83. 83. Two bolts - 4 segments<br />1mm<br />Contact: conormce@cs.nuim.ie<br />
  84. 84. Two bolts - 4 segments<br />2mm<br />Contact: conormce@cs.nuim.ie<br />
  85. 85. Depth segmentation and the reconstruction interval<br />Now we will see if we can segment it into 8 regions<br />Contact: conormce@cs.nuim.ie<br />
  86. 86. Two bolts - 8 segments<br />0.1mm<br />Contact: conormce@cs.nuim.ie<br />
  87. 87. Two bolts - 8 segments<br />0.1mm<br />Contact: conormce@cs.nuim.ie<br />
  88. 88. Two bolts - 8 segments<br />0.5mm<br />Contact: conormce@cs.nuim.ie<br />
  89. 89. Two bolts - 8 segments<br />1mm<br />Contact: conormce@cs.nuim.ie<br />
  90. 90. Two bolts - 8 segments<br />2mm<br />??<br />Contact: conormce@cs.nuim.ie<br />
  91. 91. Twin-image<br />A hologram contains a set of twin-images.<br />One at the positive distance and one at the negative.<br />They act as a noise source in each others in-focus plane.<br />DC-Free Hologram<br />Virtual Image<br />Real Image<br />355 mm<br />-355 mm<br />Contact: conormce@cs.nuim.ie<br />
  92. 92. Results – Rotating object<br />Contact: conormce@cs.nuim.ie<br />
  93. 93. Results – Rotating object<br />Questions??<br />Contact: conormce@cs.nuim.ie<br />

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