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Blending recap

This document explores essential morphological operations used in binary image processing, emphasizing concepts like dilation and erosion, which manipulate image structures based on set theory. It covers how these operations affect contours, facilitating tasks such as noise reduction and boundary extraction. The difference between opening and closing operations is highlighted, showcasing their unique impacts on image morphology. Additionally, the significance of avoiding visible seams and uniform intensity shifts is discussed to enhance image quality. Ideal for those interested in computer vision and image analysis.

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Blending recap

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Presentation Transcript

  1. Blending recap • Visible seams – edges that should not exist, should be avoided. • People are fairly insensitive to uniform intensity shifts or gradual intensity shifts.

  2. Morphological Operation • What if your images are binary masks? • Binary image processing is a well-studied field, based on set theory, called Mathematical Morphology Slides from Alexei Efros

  3. Preliminaries

  4. Preliminaries

  5. Preliminaries

  6. Basic Concepts in Set Theory • A is a set in , a=(a1,a2) an element of A, aA • If not, then aA • : null (empty) set • Typical set specification: C={w|w=-d, for d  D} • A subset of B: AB • Union of A and B: C=AB • Intersection of A and B: D=AB • Disjoint sets: AB=  • Complement of A: • Difference of A and B: A-B={w|w  A, w  B}=

  7. Preliminaries

  8. Dilation and Erosion • Two basic operations: • A is the image, B is the “structural element”, a mask akin to a kernel in convolution • Dilation : • (all shifts of B that have a non-empty overlap with A) • Erosion : • (all shifts of B that are fully contained within A)

  9. Dilation

  10. Dilation

  11. Erosion

  12. Erosion Original image Eroded image

  13. Erosion Eroded once Eroded twice

  14. Opening and Closing • Opening : smoothes the contour of an object, breaks narrow isthmuses, and eliminates thin protrusions • Closing : smooth sections of contours but, as opposed to opning, it generally fuses narrow breaks and long thin gulfs, eliminates small holes, and fills gaps in the contour • Prove to yourself that they are not the same thing. Play around with bwmorph in Matlab.

  15. Opening and Closing OPENING: The original image eroded twice and dilated twice (opened). Most noise is removed CLOSING: The original image dilated and then eroded. Most holes are filled.

  16. Opening and Closing

  17. Boundary Extraction

  18. Boundary Extraction

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