Method and apparatus for image enhancement for the visually impaired

US 20040136570A1
Filed: 10/03/2003
Published: 07/15/2004
Est. Priority Date: 04/30/2002
Status: Abandoned Application

First Claim

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1. A method for enhancing an image for a visually impaired person, comprising the steps of determining at least one discrete feature of an image, and modifying the determined feature to alter its appearance to a visually impaired person.

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Abstract

A method and apparatus providing good image enhancement for the visually impaired utilizing the “Ullman-Zur enhancement” algorithm. The method and apparatus consists in obtaining an original image, detecting and enhancing the edges and lines of the image by using Balanced Difference of Gaussians to obtain a first processed image, smoothing the original image by using a convolution of the original image with Gaussian, enhancing the contrast of the smoothed image, calculating the intensity average, AC, and the standard deviation of the intensity, SDC, of the chosen region, and stretching the intensity of the smoothed image linearly according to AC, SDC, and some specific rules to obtain a second processed enhanced image. The first processed image is superimposed on the second processed enhanced image to obtain the final enhanced image that is more readily perceived by a visually impaired person.

123 Citations

79 Claims

1. A method for enhancing an image for a visually impaired person, comprising the steps of determining at least one discrete feature of an image, and modifying the determined feature to alter its appearance to a visually impaired person.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
- - 2. The method of claim 1 further including the step of at least one of magnification of the image, contrast enhancement of the whole image, contrast enhancement of local frequency range of the image and contrast enhancement of local spatial range of the image.
  - 3. The method of claim 1 wherein the step of modifying the determined feature includes the step of at least one of adding, removing, enhancing and diminishing the determined feature.
  - 4. The method of claim 1 wherein the image is obtained from a video stream.
  - 5. The method of claim 4 wherein the modification occur offline before the image is presented.
  - 6. The method of claim 4 wherein the modification occur in real-time while the images are presented.
  - 7. The method of claim 1 wherein the modification is controlled in real-time by a human observer of the image.
  - 8. The method of claim 1 wherein the step of modifying the determined feature includes the step of changing the spatial density in the image.
  - 9. The method of claim 1 wherein the step of modifying the determined feature includes the step of changing the spatial regularity of the image.
  - 10. The method of claim 1 wherein the step of modifying the determined feature includes the step of changing the size and shape of the image.
  - 11. The method of claim 1 wherein the step of modifying the determined feature includes the step of replacing said feature in the image with a template of the same type.
  - 12. The method of claim 1 wherein the step of modifying the determined feature includes the step of changing selectively part of the feature of the image according to predefined rules.

13. A method for enhancing an image for a visually impaired person, comprising the steps of modifying discrete features of the image to alter their appearance to a visually impaired person.
- View Dependent Claims (14, 15, 16, 17)
- - 14. A method for enhancing an image according to claim 13 further including the steps of enhancing selectively part of the features of the image according to predefined rules, and diminishing the rest of the image.
  - 15. A method for enhancing an image according to claim 14 including the step of spatially smoothing the background.
  - 16. A method for enhancing an image according to claim 14 wherein the background is contracted to intermediate intensities.
  - 17. A method for enhancing an image according to claim 14 wherein the background is stretched to a bounded range of intensities.

18. A method of enhancing an image comprising the steps of determining relevant discrete lines and discrete edges in the image, and enhancing the determined lines and images.
- View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 40, 41, 42, 43)
- - 19. A method of enhancing an image according to claim 18 wherein the relevant lines and edges in the image are enhanced by replacing each relevant line or edge by a combination of a line adjacent to an edge.
  - 20. A method of enhancing an image according to claim 18 wherein the relevant lines and edges in the image are enhanced by replacing each relevant line and edge by a patch of line grating.
  - 21. A method of enhancing an image according to claim 18 wherein the relevant lines and edges in the image are enhanced by replacing each relevant line and edge by a Gabor patch.
  - 22. A method of enhancing an image according to claim 18 wherein the relevant lines and edges in the image are enhanced by replacing each relevant line and edge by two adjacent lines, one bright and one dark.
  - 23. A method of enhancing an image according to claim 18 wherein the relevant lines and edges in the image are enhanced by replacing each relevant line and edge by two adjacent lines, one bright and one dark, and the bright line is located at the brighter side of the background surrounding the two lines, and the dark line is located at the darker side of the background surrounding the two lines.
  - 24. A method of enhancing an image according to claim 18 wherein the relevant lines and edges in the image are enhanced by replacing each relevant line and edge by two adjacent lines, one bright and one dark, and the intensity of the lines is stretched to extreme values.
  - 25. A method of enhancing an image according to claim 18 wherein the relevant lines and texture patterns in the image are enhanced.
  - 26. A method of enhancing an image according to claim 25 wherein the relevant lines and texture patterns in the image are enhanced by making them spatially denser.
  - 27. A method of enhancing an image according to claim 25 wherein the relevant lines and texture patterns in the image are enhanced by making them more spatially regular.
  - 28. A method of enhancing an image according to claim 25 wherein the relevant lines and texture patterns in the image are enhanced by stretching the intensity of the lines and texture elements to extreme values.
  - 40. A method of enhancing an image according to claim 25 wherein the changed features are reduced by spatial filtering.
  - 41. A method of enhancing an image according to claim 25 wherein the changed features are reduced by temporal filtering.
  - 42. A method of enhancing an image according to claim 25 wherein the changed features are reduced by spatially oriented filtering.
  - 43. A method of enhancing an image according to claim 25 wherein the changed features are reduced by temporally continuous filtering.

29. A method for enhancing an image comprising the steps of detecting characters in an image, and enhancing the detected characters.
- View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39)
- - 30. A method according to claim 29 wherein lines and characters in the image are enhanced by modifying their size.
  - 31. A method according to claim 29 wherein the lines and characters in the image are enhanced by modifying line attributes and fonts of the characters.
  - 32. A method according to claim 29 wherein the lines and characters in the image are enhanced by modifying the space between lines and between characters.
  - 33. A method of enhancing an image according to claim 29 wherein relevant lines and texture patterns in the image are enhanced by modifying the space between lines, between characters, and between words.
  - 34. A method according to claim 29 wherein lines and characters in the image are enhance by modifying contrast of the lines, characters and their background.
  - 35. A method according to claim 29 wherein a line grating is added adjacent to lines and to edges of the characters.
  - 36. A method according to claim 29 wherein a Gabor patch is added adjacent to lines and to edges of the characters.
  - 37. A method according to claim 29 including the further step of adding a line adjacent to existing lines, and/or to edges of the characters.
  - 38. A method according to claim 29 wherein a line is added adjacent to existing lines, and to edges of the characters, while the intensity of the characters and their adjacent lines have extreme values in an opposed way, and the background of the characters with the adjacent lines having intermediate intensity value.
  - 39. A method according to claim 29 wherein a line is added adjacent to existing lines, and to edges of characters, with the characters and the adjacent lines have high color contrast, and their background having intermediate color contrast.

44. An image enhancement method for enhancing relevant features of an image comprising the following steps:
- e. capturing the intensity channel of the image;
  
  f. detecting and signing the relevant features in the intensity channel of the image;
  
  g. changing discrete relevant features in the intensity channel of the image; and
  
  h. compensating the rest of the channels for the change.

45. An image enhancement method comprising the steps of:
- h. capturing the intensity channel of the image;
  
  i. detecting and signing the relevant features in the intensity channel of the image;
  
  j. smoothing the original image;
  
  . k. contracting or stretching the intensity channel of the smoothed image between predefined intensity limits;
  
  l. compensating the rest of the channels for the contraction or stretching;
  
  m. changing the relevant features in the intensity channel of the contrast contracted or stretched and smoothed image; and
  
  n. compensating the rest of the channels for the change;
  
  whereby relevant features of the image are enhanced and background of an image diminished.
- View Dependent Claims (46, 47, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71)
- - 46. An image enhancement method according to claim 45 wherein step f includes superimposing substituting features for the relevant edges and lines on the intensity channel of the contrast contracted (or stretched) and smoothed image.
  - 47. An image enhancement method according to claim 45 wherein step f includes making relevant lines and texture patterns denser and more regular in the intensity channel of the contrast contracted (or stretched) and smoothed image.
  - 50. An image enhancement method according to claim 45 in which the smoothness level of the background is controlled in offline.
  - 51. An image enhancement method according to claim 45 in which the smoothness level of the background is controlled in real-time.
  - 52. An image enhancement method according to claim 45 in which the contraction (or stretching) level of the background is controlled in offline.
  - 53. An image enhancement method according to claim 45 in which the contraction (or stretching) level of the background is controlled in real-time.
  - 54. An image enhancement method according to claim 45 in which the density of the enhancing lines is controlled in offline.
  - 55. An image enhancement method according to claim 45 in which the density of the enhancing lines is controlled in real-time.
  - 56. An image enhancement method according to claim 45 in which width of enhancing lines is controlled in offline.
  - 57. An image enhancement method according to claim 45 in which width of enhancing lines is controlled in real-time.
  - 58. An image enhancement method according to claim 45 in which regularity of enhanced texture is controlled in offline.
  - 59. An image enhancement method according to claim 45 in which the regularity of the enhanced texture is controlled in real-time.
  - 60. An image enhancement method according to claim 45 in which density of enhanced texture is controlled in offline.
  - 61. An image enhancement method according to claim 45 in which density of enhanced texture is controlled in real-time.
  - 62. An image enhancement method according to claim 45 including substituting relevant edges and lines with two adjacent lines and diminishing background of an image, in which the smoothness of the background is controlled by the width of the Gaussian G_σ
    - ₁.
  - 63. An image enhancement method according to claim 45 that substitutes the relevant edges and lines with two adjacent lines and diminishes the background, in which the contraction (or stretching) level of the background is controlled by the lower and upper limits values K₁, K₂, M₁, M₂.
  - 64. An image enhancement method according to claim 45 that substitutes the relevant edges and lines with two adjacent lines and diminishes the background, in which the density and the width of the enhancing lines is controlled by the parameters of the DOG, G_σ
    - ₀−
      
      α
      
      ·
      
      G_β
      
      ·
      
      σ₀, and the thresholds values A and B.
  - 65. An image enhancement method according to claim 45 that substitutes the relevant edges and lines with two adjacent lines and diminishes the background, in which the two-dimensional convolutions are implemented by an equivalent successive one-dimensional convolutions.
  - 66. An image enhancement method according to claim 45 that substitutes the relevant edges and lines with two adjacent lines and diminishes the background, in which the two-dimensional convolutions are implemented by an equivalent FFT transformations.
  - 67. A character image enhancement method, comprising the following steps:
    - c. manipulating the lines and characters in the image, and d. applying an image enhancement method according to claim 45 on the manipulated image to enhance discrete lines and characters in the image.
  - 68. A method according to claim 67 wherein the lines and characters in the image are manipulated by using the following steps:
    - j. capturing the intensity channel of the image;
      
      k. detecting and signing the lines and characters in the intensity channel of the image by using an Optical Characters Recognition (OCR) or threshold algorithm;
      
      l. changing the attributes of the lines and fonts of the characters in the intensity channel of the image;
      
      m. changing the size of the lines and characters in the intensity channel of the image;
      
      n. changing the space between the lines and characters in the intensity channel of the image;
      
      o. changing the space between words in the intensity channel of the image;
      
      p. changing the color contrast between the lines and characters and their background;
      
      q. changing the brightness contrast between the lines and characters and their background;
      
      r. compensating the rest of the channels for the changes.
  - 69. A method according to claim 67 that applies the following image enhancement method on the manipulated lines and characters:
    - g. capturing the intensity channel V₀(x, y)=max(R₀, G₀, B₀) of the image IM₀(x, y);
      
      h. signing the relevant edges and lines by convoluting the intensity channel of the original image with Difference of Gaussian (DOG);
      
      V₁=(G_σ₀−
      
      α
      
      ·
      
      G_β
      
      ·
      
      σ_o)*V₀where G_σ(x, y) is a Gaussian function with zero average and σ
      
      Standard deviation, $G_{σ} (x, y) = \frac{1}{2 {Πσ}^{2}} e^{\frac{x^{2} + y^{2}}{2 σ^{2}}}$ α
      
      is the balance ratio and β
      
      is the space ratio;
      
      i. smoothing all the channels of the original image (R₀,G₀,B₀) by convoluting it with an average operator, such as a gaussian smoother;
      
      Im₂=G_σ₁*Im₀;
      
      j. contracting (or stretching) the contrast of the intensity channel of the smoothed image V₂=max(R₂, G₂, B₂) between predefined limits, by using percentage enhancement;
      
      ${\begin{matrix} if K_{1} < V_{2} (x, y) < K_{2} then \\ V_{3} (x, y) = (V_{2} (x, y) - K_{1}) \cdot \frac{M_{2} - M_{1}}{K_{2} - K_{1}} + M_{1} \\ else if V_{2} (x, y) \geq K_{2} then \\ V_{3} (x, y) = M_{2} \\ else \\ V_{3} (x, y) = M_{1} \end{matrix}$ where K₁and K₂are lower and upper limits, appropriately, in the intensity channel of the smoothed image, and M₁and M₂are lower and upper limits, appropriately, in the intensity channel of the contracted (stretched) image;
      
      k. compensating the rest of the channels of Im₃(x, y) for the contraction (or stretching) (d) by keeping the relations $\frac{R_{3}}{G_{3}} = \frac{R_{2}}{G_{2}}, \frac{G_{3}}{B_{3}} = \frac{G_{2}}{B_{2}} .;$ l. superimposing the two adjacent lines on the relevant edges and lines in the intensity channel of the contrast contracted (stretched) and smoothed image by using the following rule;
      
      ${\begin{matrix} if V_{1} (x, y) \geq A then \\ V_{4} (x, y) = 0 \\ else if V_{1} (x, y) \leq B then \\ V_{4} (x, y) = 255 \\ else \\ V_{4} (x, y) = V_{3} (x, y) \end{matrix}$ where A and B are the upper and lower thresholds; and
      
      g) compensating the rest of the channels of Im₄(x, y) for the superimposition (f) by keeping the relations $\frac{R_{4}}{G_{4}} = \frac{R_{3}}{G_{3}}, \frac{G_{4}}{B_{4}} = \frac{G_{3}}{B_{3}} .$
  - 70. The method of claim 45 further including a size test for determining the quality of results comprising the further steps of:
    - e. presenting the image to a visually impaired with a size, which is below the recognition or perception threshold;
      
      f. increase the image size gradually;
      
      g. letting the visually impaired sign when he/she first identifies the object or perceive the feature in the image; and
      
      h. ranking the quality of the image according to the identification or the perception size.
  - 71. The method of claim 45 further including a contrast test for determining the quality of results comprising the further steps of:
    - e. presenting the image to the visually impaired with a contrast;
      
      which is below the recognition or perception threshold;
      
      f. increasing the image contrast gradually;
      
      g. letting the visually impaired to sign when he/she first identifies the object or perceive the feature in the image; and
      
      h. ranking the quality of the image according to the identification or the perception contrast; and
      
      /or a simulation test for determining the quality of results comprising the further steps of;
      
      a. simulating damages and perceptual effects of visually impaired individual;
      
      b. transforming an enhanced image according to the simulation;
      
      c. transforming the original images according to the simulation;
      
      d. ranking the quality according to comparison of the transformation results on the original and enhanced images.

48. An image enhancement method that substitutes relevant edges and lines with two adjacent lines and diminishes the background of the image comprising the following steps:
- h. capturing the intensity channel I₀(x, y) of the image Im₀(x, y) i. signing the relevant edges and lines by convoluting the intensity channel of the original image with Difference of Gaussian (DOG);
  
  I₁=(G_σ₀−
  
  α
  
  ·
  
  G_β
  
  ·
  
  σ₀)*I₀Where G_σ(x, y) is a Gaussian function with zero average and σ
  
  Standard deviation, $G_{σ} (x, y) = \frac{1}{2 \prod σ^{2}} e^{\frac{x^{2} + y^{2}}{2 σ^{2}}}$ α
  
  is the balance ratio and β
  
  is the space ratio;
  
  j. smoothing all the channels of the original image by convoluting it with an average operator, such as a gaussian smoother;
  
  Im₂=G_σ₁*Im₀k. contracting (or stretching) the contrast of the intensity channel of the smoothed image between predefined limits, by using percentage enhancement;
  
  ${\begin{matrix} if K_{1} < I_{2} (x, y) < K_{2} then \\ I_{3} (x, y) = (I_{2} (x, y) - K_{1}) \cdot \frac{M_{2} - M_{1}}{K_{2} - K_{1}} + M_{1} \\ else if I_{2} (x, y) \geq K_{2} then \\ I_{3} (x, y) = M_{2} \\ else \\ I_{3} (x, y) = M_{1} \end{matrix}$ where K₁and K₂are lower and upper limits, appropriately, in the intensity channel of the smoothed image, and M₁and M₂are lower and upper limits, appropriately, in the intensity channel of the contracted (stretched) image;
  
  l. compensating the rest of the channels of Im₃(x, y) for the contraction (or stretching);
  
  m. superimposing the two adjacent lines on the relevant edges and lines in the intensity channel of the contrast contracted (stretched) and smoothed image by using the following rule;
  
  ${\begin{matrix} if I_{1} (x, y) \geq A then \\ I_{4} (x, y) = 0 \\ else if I_{1} (x, y) \leq B then \\ I_{4} (x, y) = 255 \\ else \\ I_{4} (x, y) = I_{3} (x, y) \end{matrix}$ where A and B are the upper and lower thresholds; and
  
  n. compensating the rest of the channels of Im₄(x, y) for the superimposition (f).

49. An image enhancement method that substitutes relevant edges and lines with two adjacent lines and diminishes the background of an image by using HSV and RGB color image formats comprising the following steps:
- g. capturing the intensity channel V₀(x, y)=max(R₀, G₀, B₀) of the image IM₀(x,y);
  
  h. signing the relevant edges and lines by convoluting the intensity channel of the original image with Difference of Gaussian (DOG);
  
  V₁=(G_σ₀−
  
  α
  
  ·
  
  G_β
  
  ·
  
  σ₀)*V₀where G_σ(x, y) is a Gaussian function with zero average and σ
  
  Standard deviation, $G_{σ} (x, y) = \frac{1}{2 \prod σ^{2}} e^{\frac{x^{2} + y^{2}}{2 σ^{2}}}$ α
  
  is the balance ratio and β
  
  is the space ratio;
  
  i. smoothing all the channels of the original image (R₀,G₀,B₀) by convoluting it with an average operator, such as a gaussian smoother;
  
  Im₂=G_σ₁*Im₀j. contracting (or stretching) the contrast of the intensity channel of the smoothed image V₂=max(R₂,G₂,B₂) between predefined limits, by using percentage enhancement;
  
  ${\begin{matrix} if K_{1} < V_{2} (x, y) < K_{2} then \\ V_{3} (x, y) = (V_{2} (x, y) - K_{1}) \cdot \frac{M_{2} - M_{1}}{K_{2} - K_{1}} + M_{1} \\ else if V_{2} (x, y) \geq K_{2} then \\ V_{3} (x, y) = M_{2} \\ else \\ V_{3} (x, y) = M_{1} \end{matrix}$ where K₁and K₂are lower and upper limits, appropriately, in the intensity channel of the smoothed image, and M₁and M₂are lower and upper limits in the intensity channel of the contracted (stretched) image;
  
  k. compensating the rest of the channels of Im₃(x, y) for the contraction (or stretching) by keeping the relations $\frac{R_{3}}{G_{3}} = \frac{R_{2}}{G_{2}}, \frac{G_{3}}{B_{3}} = \frac{G_{2}}{B_{2}};$ l. superimposing the two adjacent lines on relevant edges and lines in the intensity channel of the contrast contracted (stretched) and smoothed image by using the following rule;
  
  ${\begin{matrix} if V_{1} (x, y) \geq A then \\ V_{4} (x, y) = 0 \\ else if V_{1} (x, y) \leq B then \\ V_{4} (x, y) = 255 \\ else \\ V_{4} (x, y) = V_{3} (x, y) \end{matrix}$ where A and B are the upper and lower thresholds; and
  
  g.) compensating the rest of the channels of Im₄(x, y) for the superimposition by keeping the relations $\frac{R_{4}}{G_{4}} = \frac{R_{3}}{G_{3}}, \frac{G_{4}}{B_{4}} = \frac{G_{3}}{B_{3}} .$

72. A Psychophysical test for the damage of the visually impaired observer that uses the following steps:
- a. testing the perceived uniformity of line grating with different spatial frequencies;
  
  b. testing the perceived number of missing dots in a regular array of dots with different densities; and
  
  c. testing the perceived uniformity of irregular array of dots with different irregularity levels.

73. Apparatus for image enhancement for visually impaired that substitutes relevant edges and lines of an image with two adjacent lines and diminishes the background of the image by utilizing an algorithm wherein a. the intensity channel I₀(x, y) of an image is captured Im₀(x, y);
- b. the relevant edges and lines are signed by convoluting the intensity channel of the original image with Difference of Gaussian (DOG);
  
  I₁=(G_σ₀−
  
  α
  
  ·
  
  G_β
  
  ·
  
  Γ₀)*I₀where G_σ(x, y) is a Gaussian function with zero average and σ
  
  Standard deviation, $G_{σ} (x, y) = \frac{1}{2 {Πσ}^{2}} e^{\frac{x^{2} + y^{2}}{2 σ^{2}}}$ α
  
  is the balance ratio and β
  
  is the space ratio;
  
  c. all the channels of the original image are smoothing by convoluting it with an average operator, such as a gaussian smoother;
  
  Im₂=G_σ₁*Im₀;
  
  d. the contrast of the intensity channel of the smoothed image is contracting (or stretching) between predefined limits, by using percentage enhancement;
  
  ${\begin{matrix} if K_{1} < I_{2} (x, y) < K_{2} then \\ I_{3} (x, y) = (I_{2} (x, y) - K_{1}) \cdot \frac{M_{2} - M_{1}}{K_{2} - K_{1}} + M_{1} \\ else if I_{2} (x, y) \geq K_{2} then \\ I_{3} (x, y) = M_{2} \\ else \\ I_{3} (x, y) = M_{1} \end{matrix}$ where K₁and K₂are lower and upper limits, appropriately, in the intensity channel of the smoothed image, and M₁and M₂are lower and upper limits, appropriately, in the intensity channel of the contracted (stretched) image;
  
  k. the rest of the channels of Im₃(x, y) are compensated for the contraction (or stretching);
  
  l. the two adjacent lines on the relevant edges and lines in the intensity channel of the contrast contracted (stretched) and smoothed image are superimposed by using the following rule;
  
  ${\begin{matrix} if I_{1} (x, y) \geq A then \\ I_{4} (x, y) = 0 \\ else if I_{1} (x, y) \leq B then \\ I_{4} (x, y) = 255 \\ else \\ I_{4} (x, y) = I_{3} (x, y) \end{matrix}$ where A and B are the upper and lower thresholds; and
  
  the rest of the channels of Im₄(x, y) are compensated for the superimposition.
- View Dependent Claims (75, 76, 77, 78, 79)
- - 75. Apparatus according to claim 73 wherein the parameters of the system filters, transformation, operators, functionality, operation, and mode of operation are adjustable.
  - 76. Apparatus according to claim 73 wherein the adjustment of the parameters influences the output image.
  - 77. Apparatus according to claim 73 wherein the apparatus includes one of the following:
    - g. an input tuner that receives the video images in the input format and transceives them to base band;
      
      h. an Analog to Digital transceiver that samples the video frames;
      
      i. a computerized processor that modifies the sampled images;
      
      j. a digital to Analog transceiver that integrates the frames to analog video stream;
      
      k. an output mixer that transforms the base band video stream to the desired output format; and
      
      l. control panel (local or remote) enabling to control running of parameters of the method, and tests.
  - 78. Apparatus according to claim 73 that is housed in one of:
    - q. a “
      
      Set top”
      
      box at the input of a TV set or a VCR (VideoCassette Recorder)—
      
      local enhancement;
      
      r. server of a TV (Television) content provider, such as the Cables or the Satellite stations (remote enhancement);
      
      s. a Digital TV, such as High Definition TV;
      
      t. Digital VCR player;
      
      u. DVD (Digital Versatile Disc) player;
      
      v. Close Circuit TV;
      
      w. Personal Computer (PC) card;
      
      x. Personal Computer package;
      
      y. PDA (Personal Digital Assistant). z. Handheld computer;
      
      aa. Pocket PC;
      
      bb. Multimedia Player;
      
      cc. Computer card;
      
      dd. Internet server;
      
      ee. Chip set;
      
      ff. an apparatus at the input of a head mounted display.
  - 79. Apparatus according to claim 73 which is used for:
    - d. Improving the visual perception of visually impaired individual. e. Improving of Infrared images for observer with normal vision. f. Improving of Ultrasound images for observer with normal vision.

74. Apparatus for image enhancement for visually impaired that substitutes relevant edges and lines of an image with two adjacent lines and diminishes the background of an image by using HSV and RGB color image formats by utilizing an algorithm wherein g. the intensity channel V₀(x, y)=max(R₀,G₀, B₀) of the image. Im₀(x, y) is captured;
- h. the relevant edges and lines are signed by convoluting the intensity channel of the original image with Difference of Gaussian (DOG);
  
  V₁=(G_σ₀−
  
  α
  
  ·
  
  G_β
  
  ·
  
  σ₀)*V₀where G_σ(x, y) is a Gaussian function with zero average and σ
  
  Standard deviation, $G_{σ} (x, y) = \frac{1}{2 {Πσ}^{2}} e^{\frac{x^{2} + y^{2}}{2 σ^{2}}}$ α
  
  is the balance ratio and β
  
  is the space ratio;
  
  i. all the channels of the original image (R₀,G₀,B₀) are smoothed by convoluting it with an average operator, such as a gaussian smoother;
  
  Im₂=G_σ₁*Im₀;
  
  j. the contrast of the intensity channel of the smoothed image V₂=max(R₂,G₂,B₂) is contracted (or stretched) between predefined limits, by using percentage enhancement;
  
  ${\begin{matrix} if K_{1} < V_{2} (x, y) < K_{2} then \\ V_{3} (x, y) = (V_{2} (x, y) - K_{1}) \cdot \frac{M_{2} - M_{1}}{K_{2} - K_{1}} + M_{1} \\ else if V_{2} (x, y) \geq K_{2} then \\ V_{3} (x, y) = M_{2} \\ else \\ V_{3} (x, y) = M_{1} \end{matrix}$ where K₁and K₂are lower and upper limits, appropriately, in the intensity channel of the smoothed image, and M₁and M₂are lower and upper limits in the intensity channel of the contracted (stretched) image;
  
  k. the rest of the channels of Im₃(x, y) are compensated for the contraction (or stretching) by keeping the relations $\frac{R_{3}}{G_{3}} = \frac{R_{2}}{G_{2}}, \frac{G_{3}}{B_{3}} = \frac{G_{2}}{B_{2}};$ l. the two adjacent lines on relevant edges and lines in the intensity channel of the contrast contracted (stretched) and smoothed image are superimposed by using the following rule;
  
  ${\begin{matrix} if V_{1} (x, y) \geq A then \\ V_{4} (x, y) = 0 \\ else if V_{1} (x, y) \leq B then \\ V_{4} (x, y) = 255 \\ else \\ V_{4} (x, y) = V_{3} (x, y) \end{matrix}$ where A and B are the upper and lower thresholds; and
  
  g.) the rest of the channels of Im₄(x, Y) are compensated for the superimposition by keeping the relations $\frac{R_{4}}{G_{4}} = \frac{R_{3}}{G_{3}}, \frac{G_{4}}{B_{4}} = \frac{G_{3}}{B_{3}} .$

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Current Assignee
Dror Zur, Shimon Ullman
Original Assignee
Dror Zur, Shimon Ullman
Inventors
Zur, Dror, Ullman, Shimon

Application Number

US10/473,780
Publication Number

US 20040136570A1
Time in Patent Office

Days
Field of Search
US Class Current

382/114
CPC Class Codes

G06T 5/75 Unsharp masking

G09B 21/008 using visual presentation o...

Method and apparatus for image enhancement for the visually impaired

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Method and apparatus for image enhancement for the visually impaired

First Claim

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Accused Products

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Abstract

123 Citations

79 Claims

Specification

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Solutions

Use Cases

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