User definable windows for selecting image processing regions

Claims

What is claimed is:

1. A computer-implemented process for selectively applying image processing to a selected region of a target image provided by an image source, the process being carried out in a computer system coupled to the image source, comprising the steps of:

obtaining a key frame image from an image provided by an image source;

in response to user commands, defining a key from the key frame image, the key corresponding to the selected region of interest for applying image processing to the target image;

automatically vectorizing the region of interest in the key to derive a user defined window; and

applying image processing within the region of the target image corresponding to the user defined window of the key.

2. The computer-implemented process of claim 1, wherein the image processing is selected from the group color correction, image compression, noise reduction, colorization, and animation.

3. The computer-implemented process of claim 1, wherein the step of automatically vectorizing comprises drawing a continuous polygon drawn around the selected region of interest in the key, the continuous polygon comprising a predetermined number of points specified by the user.

4. The computer-implemented process of claim 1, further comprising the step of:

in response to user commands, editing characteristics of the user defined window to allow the user to adapt the window to the key.

5. The computer-implemented process of claim 1, further comprising the steps of:

in response to a user command, capturing the luminance characteristics of the key frame image from the image source in a key frame buffer;

in response to user commands, adjusting video parameters of the key frame image in the key frame buffer to isolate a region of interest according to video characteristics; and

in response to user commands, adjusting regions of the key frame image to isolate the region of interest according to geometric characteristics.

6. The computer-implemented process of claim 1, further comprising the steps of:

in response to user commands, defining a first user defined window for a first frame of a scene comprising a plurality of images;

in response to user commands, defining a second user defined window for a last frame of the scene;

automatically transforming the first user defined window into the second user defined window during the plurality of images during a playback of the scene;

applying the image processing within the region defined by the user defined windows for each frame of the scene during playback on a real time basis.

7. The computer-implemented process of claim 6, wherein the step of automatically transforming the first user defined window into the second user defined window comprises linearly transforming corresponding points of the first user defined window to corresponding points of the second user defined window successively for each frame of the plurality of frames in the scene.

8. The computer-implemented process of claim 1, further comprising the step of applying a softness filter to boundaries of the user defined window so as to apply image processing on a predetermined gradient.

9. The computer-implemented process of claim 1, wherein the user defined window created in the step of automatically vectorizing is limited to a predetermined number of points that can be devectorized on a real time basis to create a digital matte for applying the image processing.

10. The computer-implemented process of claim 1, further comprising the step of deriving a plurality of user defined windows corresponding to a plurality of regions of interest for applying image processing.

11. The computer-implemented process of claim 1, further comprising the step of applying a different type of image processing to regions of the image outside the user defined window.

12. The computer-implemented process of claim 11, wherein the step of applying image processing within the region of the image defined by the user defined window comprises applying a first set of color corrections in a scene-by-scene color corrector; and

wherein the step of applying image processing to regions of the image outside the user defined window comprises applying a second set of color corrections.

13. A system for selectively applying image processing to a selected region of an image on a frame by frame basis in a scene comprising a plurality of frames, comprising:

a memory for storing at least one user defined window corresponding to the selected region in one of the images of the scene, the user defined window comprising a vector representation of the selected region;

a component for spatially transforming the at least one user defined window defined for a first frame of the scene into a user defined window for a final frame of the scene, thereby providing a transforming succession of user defined windows, one associated with each frame of the scene;

a component for deriving from the user defined window a matte corresponding to each user defined window of the transforming succession in real time on a frame by frame basis, each matte including a processing region; and

a component for applying image processing within the processing region of each frame corresponding to the user defined window associated with each frame.

14. The system of claim 13, further comprising:

a component for capturing and storing a key frame image from one of the frames of the scene, and

a component for isolating a bit map key from the stored key frame image, the key corresponding to the selected region for applying image processing; and

a component for automatically vectorizing the key to derive a user defined window.

15. The system of claim 14, further comprising:

user controls for adjusting video parameters of the key frame image to isolate the region of interest according to video characteristics;

user controls for adjusting regions of the key frame image to isolate the region of interest according to geometric characteristics.

16. The system of claim 13, further comprising user controls for editing characteristics of the user defined window to allow the user to adapt the window to the region of interest.

17. The system of claim 16, wherein the user controls for editing characteristics of the user defined window include a tool for adjusting the number of points representing the vector representation of the window.

18. The system of claim 13, wherein the user controls for editing characteristics of the user defined window include a tool for adjusting the location of one or more selected points of a window.

19. The system of claim 13, wherein the component for applying image processing comprises:

a circuit responsive to the user defined window for devectorizing the window to obtain a digital matte;

an image processing device; and

a keyer for applying image processing via the image processing device in accordance with regions corresponding to the digital matte.

20. The system of claim 19, wherein the digital matte comprises an array of digital values of a predetermined resolution, and wherein the image processing is applied in accordance with the values of the array of the digital values.

21. The system of claim 20, further comprising a softness filter operative for applying image processing on a predetermined gradient to boundaries of the user defined window.

22. The system of claim 19, wherein the image processing device is a digital scene-by-scene color corrector.

23. A computer-implemented process for creating a user defined window for applying image processing to a target image, the process being carried out in a computer system coupled to an image source, comprising the steps of:

in response to a user command, capturing in a key frame buffer the luminance characteristics of a key frame image corresponding to a target image obtained from the image source;

in response to user commands, adjusting video parameters of the key frame image in the key frame buffer to define a region of interest according to video characteristics;

in response to user commands, adjusting regions of the key frame image to define the region of interest according to geometric characteristics;

in response to a user command, vectorizing the region of interest to derive a user defined window comprising a continuous polygon drawn around the key frame image, the continuous polygon comprising a predetermined number of points specified by the user;

in response to user commands, editing characteristics of the user defined window to allow the user to adapt the continuous polygon to an outline of the region of interest in the key frame image; and

applying image processing to the target image within the region defined by the user defined window.

24. The computer-implemented process of claim 23, wherein the video parameters of the key frame image comprise the luminance values of the image.

25. The computer-implemented process of claim 23, wherein the step of adjusting parameters of the key frame image to isolate the region of interest according to video characteristics is effected in response to the use of gain, clip, and limit user controls.

26. The computer-implemented process of claim 23, wherein the key frame image is stored as an array of 10-bit luminance values, and further comprising the step of converting the 10-bit luminance values to a 1-bit high contrast image prior to the step of vectorizing.

27. The computer-implemented process of claim 23, wherein the step of adjusting regions of the key frame image to isolate the region of interest according to geometric characteristics is effected in response to the use of a brush tool by the user.

28. The computer-implemented process of claim 23, wherein the step of editing characteristics of the user defined window comprises adjusting the number of points representing the window.

29. The computer-implemented process of claim 23, wherein the step of editing characteristics of the user defined window comprises adjusting the location of one or more selected points of the window.

30. The computer-implemented process of claim 23, further comprising the step of storing the 1-bit key image in memory for later recall, further editing, or use.

31. The computer-implemented process of claim 23, further comprising the step of storing the edited user window in memory for later recall, further editing, or use.

32. The computer-implemented process of claim 23, further comprising steps for:

in response to user commands, defining a first user defined window for a first frame of a scene comprising a plurality of images;

in response to user commands, defining a second user defined window for a last frame of the scene;

automatically transforming the first user defined window into the second user defined window during the plurality of images during a playback of the scene;

applying the image processing within the region defined by the user defined window for each frame of the scene.

33. The computer-implemented process of claim 32, wherein the step of automatically transforming the first user defined window into the second user defined window during the plurality of images during a playback of the scene comprises linearly transforming corresponding points of the first user defined window to corresponding points of the second user defined window successively for each frame of the plurality of frames in the scene.

34. The computer-implemented process of claim 32, wherein the step of automatically transforming the first user defined window into the second user defined window during the plurality of images during a playback of the scene is carried out at a real time rate.

35. The computer-implemented process of claim 23, wherein the process is carried out in a computer-based workstation associated with a scene-by-scene color corrector.

36. The computer-implemented process of claim 23, wherein the image source is associated with a scene-by-scene color corrector.

37. The computer-implemented process of claim 23, further comprising the steps of applying a softness filter to boundaries of the user defined window so as to apply image processing on a predetermined gradient.

38. A system for creating a user defined window for applying image processing to a target image, comprising:

a computer system including a memory, a processor, a display, and user interface devices;

a component for capturing and storing a key frame image corresponding to the target image in the memory;

at least one user control for adjusting at least one parameter of the key frame image to define a region of interest for applying image processing;

a component for vectorizing the defined region of the key frame image to derive a user defined window comprising a continuous polygon drawn around the defined region of interest in the key frame image, the continuous polygon comprising a predetermined number of points specified by the user;

user tools for editing characteristics of the user defined window to allow the user to adapt the continuous polygon to the outline of the defined region of interest in the key frame image; and

a component for applying image processing to the target image within the region corresponding to the user defined window.

39. The system of claim 38, wherein the video parameters of the key frame image comprise the luminance values of the target image.

40. The system of claim 38, wherein the at least one user control for adjusting at least one parameter of the key frame image to define the region of interest comprise video gain, clip, and limit controls.

41. The system of claim 38, wherein the key frame image is stored as an array of 10-bit luminance values and further comprising a component for converting the 10-bit luminance values to a 1-bit high contrast image prior to provision to the vectorizing component.

42. The system of claim 38, wherein the user controls for adjusting regions of the key frame image to define the region of interest according to geometric characteristics include a software brush tool.

43. The system of claim 38, wherein the user controls for adjusting regions of the key frame image according to geometric characteristics include tools for adjusting the number of points representing a window.

44. The system of claim 38, wherein the user controls for adjusting regions of the key frame image according to geometric characteristics include tools for adjusting the location of one or more selected points of a window.

45. The system of claim 38, further comprising a component storing the key frame image in memory for later recall, further editing, or use.

46. The system of claim 38, further comprising a component for storing the user defined window in memory for later recall, further editing, or use.

47. The system of claim 38, wherein the component for applying image processing comprises:

a circuit responsive to the user defined window for devectorizing the window to obtain a digital matte;

an image processing device; and

a keyer for applying image processing via the image processing device in accordance with regions corresponding to the digital matte.

48. The system of claim 47, wherein the digital matte comprises an array of digital values of a predetermined resolution, and wherein the image processing is applied in accordance with the values of the array of the digital values.

49. The system of claim 47, further comprising a softness filter operative for applying image processing on a predetermined gradient to boundaries of the user defined window.

50. The system of claim 47, wherein the image processing device is a scene-by-scene color corrector.

51. The system of claim 50, wherein the system is operative for:

defining a first user defined window for a first frame of a scene comprising a plurality of images;

defining a second user defined window for a last frame of the scene;

automatically transforming the first user defined window into the second user defined window during the plurality of images during a playback of the scene;

applying the image processing within the region defined by the user defined window for each frame of the scene.

52. The system of claim 51, wherein the operation of automatically transforming the first user defined window into the second user defined window during the plurality of images during a playback of the scene comprises linearly transforming corresponding points of the first user defined window to corresponding points of the second user defined window successively for each frame of the plurality of frames in the scene.

53. The system of claim 51, wherein the operation of automatically transforming the first user defined window into the second user defined window during the plurality of images during a playback of the scene is carried out at a real time rate.

54. A computer-implemented process for applying image processing to a scene of images comprising a plurality of frames, the process being carried out in a computer system coupled to an image source, the computer system including a processor, a display and a memory, comprising the steps of:

obtaining a first key frame image from an image provided by an image source;

defining a first user defined window comprising a continuous polygon corresponding to a region of interest in the key frame image;

storing the first user defined window in the memory;

obtaining a second key frame image from an image provided by the image source;

defining a second user defined window comprising a continuous polygon corresponding to a region of interest in the second key frame image;

storing the second user defined window in the memory;

retrieving the first user defined window from the memory;

displaying the first user defined window on the display;

in response to user commands, modifying the first user defined window to adapt the first user defined window to a region of interest in a first frame of the scene;

retrieving the second user defined window from the memory;

displaying the second user defined window on the display;

in response to user commands, modifying the second user defined window to adapt the second user defined window to a region of interest in a final frame of the scene;

automatically transforming the first user defined window into the second user defined window during playback of the scene from the first frame of the scene to the final frame of the scene; and

applying the image processing within the region defined by the user defined window for each frame of the scene during playback of the scene.

55. The computer-implemented process of claim 54, further comprising the steps of:

in response to a user command, capturing the key frame image from a selected image of the scene in the memory;

in response to user commands, defining the region of interest in the key frame image; and

in response to a user command, vectorizing the region of interest the key image to derive the user defined window.

56. The computer-implemented process of claim 55, wherein the step of defining the region of interest in the key frame image comprises adjusting video parameters of the key frame image to isolate the region of interest according to video characteristics.

57. The computer-implemented process of claim 56, wherein the step of adjusting video parameters of the key frame image is effected in response to the use of gain, clip, and limit user controls.

58. The computer-implemented process of claim 55, wherein the key frame image is stored as an array of 10-bit luminance values, and further comprising the step of converting the 10-bit luminance values to a 1-bit high contrast image prior to the step of vectorizing.

59. The computer-implemented process of claim 55, wherein the step of defining the region of interest in the key frame image comprises adjusting regions of the key frame image according to geometric characteristics.

60. The computer-implemented process of claim 59, wherein the step of adjusting regions of the key frame image according to geometric characteristics is effected in response to the use of a brush tool by the user.

61. The computer-implemented process of claim 54, further comprising the steps of:

in response to user commands, editing characteristics of the user defined window to allow the user to adapt the continuous polygon to the outline of the region of interest.

62. The computer-implemented process of claim 54, wherein the steps of modifying a user defined window comprises adjusting the number of points representing a window.

63. The computer-implemented process of claim 54, wherein the steps of modifying a user defined window comprises adjusting the location of one or more selected points of a window.

64. The computer-implemented process of claim 54, wherein the step of automatically transforming the first user defined window into the second user defined window during playback of the scene comprises linearly transforming corresponding points of the first user defined window to corresponding points of the second user defined window successively for each frame of the plurality of frames in the scene.

65. The computer-implemented process of claim 64, wherein the step of automatically transforming the first user defined window into the second user defined window during the plurality of images during a playback of the scene is carried out at a real time rate.

66. The computer-implemented process of claim 54, wherein the process is carried out in a computer-based workstation associated with a scene-by-scene color corrector.

67. The computer-implemented process of claim 54, further comprising the steps of applying a softness filter to boundaries of the user defined windows so as to apply image processing on a predetermined gradient.

68. The computer-implemented process of claim 1, further comprising the steps of:

deriving a matte corresponding to the user defined window, the matte including a processing region, and

wherein the step of applying image processing within the region of the target image corresponding to the user defined window comprises image processing within the processing region.

69. The system of claim 38, wherein the parameters of the key frame image comprise video parameters.

70. The system of claim 38, wherein the parameters of the key frame image comprise geometric characteristics.

71. The system of claim 38, wherein the parameters of the key frame image comprise geometric parameters.

TECHNICAL FIELD

The present invention relates generally to image processing, and more particularly relates to a system and methods that allow a user of an image processing system such as a scene by scene color corrector to define a window derived from a key image for purposes of applying image processing only to selected regions of an image.

BACKGROUND OF THE INVENTION

In certain types of image processing systems, especially color correction systems employed in post-production equipment, system operators observe an image on a video monitor, adjust color and other parameters of the image until it is aesthetically satisfactory, store the parameters in system memory, and apply the parameter corrections to a sequence of images forming a scene. Various types of image processing are often employed to create, enhance, compress, filter, or otherwise modify characteristics of an image.

In a video signal color correction system, color corrections of motion picture film and/or video tape are typically made on a scene-by-scene basis. A "scene" is a sequential collection of images shot from the same camera, having the same viewpoint, composed in a certain way, etc. A system operator or "colorist" views a selected exemplary image or frame from a scene. The colorist then applies color corrections via a control panel to adjust video parameters such as hue, saturation, luminance, etc. of a frame image being viewed. The correction settings are stored in system memory.

After the colorist is satisfied with the adjustments he or she has made to the selected frame, the correction system, which is typically computer-controlled, applies the stored color corrections to each frame in the scene one at a time. The color-corrected frames of the scene are then recorded on film or videotape. The steps are repeated for other scenes in

the film or video tape, often with different correction settings stored for different scenes. This process creates a color-corrected master film or video tape that reflects color adjustments to all frames in all scenes.

Devices are known in the art for defining a region of an image for applying one set of color corrections, with other regions of the image receiving another, separate set of color corrections. Such devices are useful when it is desired to isolate a certain area of an image to receive special image processing. For example, in color correcting a soft drink commercial it may be desirable to isolate the beverage can from the remainder of the image so as to make the colors of the beverage can stand out from the rest of the image.

U.S. Pat. No. 4,710,800 to Fearing et al. describes an apparatus for allowing operator selection of a color region of a video image based on color. The patent describes a system for generating and positioning a cursor on a video monitor to allow selection of a color region as defined by a particular hue as opposed to a geometric region. Circuitry responsive to the cursor location selects one of a plurality of color correction circuits to become operative for directing video parameter corrections such as hue, saturation, and luminance only to regions in the video image corresponding to the hue selected by the cursor. This system therefore allows application of image processing, namely color correction, to all regions of the image bearing the color that was selected with the cursor. While this system is suitable for allowing delineation of regions for receiving image processing based on color, it does not operate on the geometry of regions.

U.S. Pat. No. 4,782,384 to Tucker et al. describes a video parameter control system operative for selecting a spatial region or window in a video image for correction. A track ball allows selection of a spatial region by dragging a cursor to draw a window around an object of interest in the picture. The operator then adjusts controls that affect only the selected window or region. A first set of correction signals is stored for the selected region, and a separate second set of correction signals is stored for areas of the picture outside the selected region, thereby allowing multiple sets of corrections for a given frame. Although the Tucker et al. patent provides some teaching regarding movement of the window over a plurality of frames to effect a dissolve, the region is essentially static and the geometry is invariably that of a box.

Certain prior art image processing computer software, e.g. ADOBE PHOTOSHOP.TM., manufactured by Adobe Systems Corporation, Mountain View, Calif., employs edge detection algorithms for detecting color regions and creating paths or Bezier curves between points. Such edge detection algorithms rely upon color differences between regions to define the paths and produce odd results if there are discontinuities in the edges of a region, or if the colors defining the regions are not sufficiently dissimilar. The PHOTOSHOP.TM. software, for example, vectorizes an entire color region and provides no control over the number of points in the region. There is no way to modify a defined region except by changing region qualification parameters. For these and other reasons, this software is not suitable for real time applications such as a scene by scene color corrector.

Image region selecting capability known as the "Simple Windows" and "Power Windows" features are extensions of the foregoing Tucker et al. system. These features are provided in the RENAISSANCE 8:8:8.TM. digital color enhancer system, manufactured by the assignee of the present invention. In the Simple Windows feature, a window is a predetermined regularly shaped area or region of the video image that can be varied in size. The colors within the window are independently adjustable from the colors of the rest of the image. Primary or secondary color enhancements can occur both inside and outside a window, and each adjustment is independent of the other. The Simple Windows feature entails use of a simple geometric form--a square or rectangle--for a window shape. A Simple window is always rectangular and is defined by four points. Lines defining the window are always straight vertical or horizontal. Furthermore, there are no soft edges, that is, there is a sharp delineation between the inside and outside of the window, which sometimes produces undesirable image effects at the boundaries.

The more recent "Power Windows" feature provided more choices of the shape for the window, for example, circular, rectangular, half screen, split in the middle, etc. Windows comprising multiple squares, multiple diamonds (essentially rotated squares), horizontal and vertical bars, circles, ellipses (a warped circle), etc. can be selected by the operator. The sizes of these windows could be varied as long as the shape remained regular. Furthermore, a "soft edges" feature was provided so as to provide a gradual transition in color correction from the inside to the outside of the selected window. Power Windows, however, are still confined to regular shapes, with predefined geometry.

Many prior art systems do not effectively handle a "dissolve", where the region of interest changes in size, shape, location, and/or geometry over several frames in a scene. An object or area of interest often moves around in an image or changes geometry during a number of frames in a scene. For example, consider the case of a bottle and a glass in a scene where only the color characteristics of the bottle are desired to be adjusted. During the scene, the bottle (viewed from the side) is lifted from an initial upright position to a tilted position, rotated so that the mouth of the bottle is facing the viewer, moved toward the glass, and poured into the glass. In this scenario, the geometry of the bottle--the overall outline--changes from essentially a side view of the bottle (an irregular shape) to a top view of the bottle (a round shape). The bottle, which is not a "regular" shape, also changes in location and size.

Prior art systems that allow the definition only of predefined geometric areas are incapable of defining regions that move and change size and geometry with respect to a number of frames in a scene. Moreover, most objects in the world are not regularly shaped in the sense of being only rectangles, circles, etc. Accordingly, there is a need for a system that allows definition of an arbitrarily shaped window in accordance with a region of interest in an image, and that provides the capability for that region of interest to move as well as change size and geometry over a plurality of frames.

SUMMARY OF THE INVENTION

The present invention employs the concept of a key well known in the television arts to define regions for receiving image processing. A good example of the use of a key is that of a television weatherman superimposed on a map. The weatherman is typically shot with a video camera standing in front of a solid blue color background. Other equipment automatically generates the video weather map. Image processing equipment is readily able to discern the outline of the weatherman relative to the blue background by use of color values. The image of the weatherman, which is called a "key", is overlaid on the map by essentially providing transparency for the blue regions of the key outside the weatherman's body. This allows the weather map to show through in the blue areas, and superimposes the weatherman on top of the map.

Related principles are employed in the present invention for defining a user defined key corresponding with a predetermined region of an image and utilizing the key to derive a user defined window. Image processing such as a set of color corrections is applied within the region defined by the key-derived user defined window. A separate second type of image processing, for example a second set of color corrections, is applied in regions outside the user defined window.

Briefly described, the present invention comprises a system and methods that allow creation of user definable windows for selecting image processing regions. These windows can vary in geometry, size, and location during a number of frames in a scene. The invention is particularly useful for allowing a colorist in a video image color correction system to define windows for selecting regions for color correction. The user typically starts by capturing an exemplary image or frame of a scene for use as a "key image" or "key frame". The key image is manipulated by adjusting parameters such as gain, clip, and limit to derive one or more key regions of the image to serve as keys. The key regions are vectorized and stored in a computer system's memory in association with the key frame. The vectorized keys, which are then called "user defined windows", are then used during a plurality of frames for defining regions to receive image processing such as color correction, data compression, noise reduction, etc.

For use in a scene having a number of frames, the user defines a window for a first frame of the scene and a window for the last frame of the scene. The user may use the last frame as a key image and derive another key for defining the final window, can use and modify the window for the first frame for defining the final window, or can use modify any other previously defined window. The system then interpolates or "morphs" the window of the first frame of the scene into the window of the final frame of the scene by linear interpolation across each frame of the scene. The windows are generated on a real time, frame by frame basis so that the color correction or other image processing can be viewed by the colorist on a video monitor. The windows thus change during the sequences of frames in the scene to compensate for changes in the size, geometry, and position of the area of interest in the scene.

More particularly described, one aspect of the invention relates to a computer-implemented process for applying image processing to a scene of images comprising a plurality of frames, the process being carried out in a computer system coupled to an image source, the computer system including a processor, a display, and a memory. The process includes steps for deriving at least one user defined window comprising a continuous polygon corresponding to a region of interest in a key frame image. The user defined window as thus derived is stored in the memory. The user may use this window or retrieve another window from memory, and display the selected user defined window on the display. This window becomes a first user defined window. In response to user commands, the selected first user defined window is edited or modified to define a first user defined window corresponding to a first frame of the scene. The user then may define a new user defined window or retrieve a selected second user defined window from the memory, and display the window. In response to user commands, the selected second user defined window is modified or edited to define a second user defined window corresponding to a final frame of the scene. Then , the first user defined window is automatically transformed into the second user defined window during playback of the scene. Image processing is applied within the region defined by the user defined window(s) for each frame of the scene during such playback.

In order to obtain a key for deriving the user defined windows, in response to a user command, a key frame image from a selected image of the scene is captured and stored in the memory. In response to user commands, the region of interest in the key frame image is isolated. Then, in response to a user command, the isolated region of interest in the key image is vectorized to derive the at least one user defined window.

The step of isolating the region of interest in the key frame image preferably comprises adjusting video parameters of the key frame image to isolate the region of interest according to video characteristics. Adjustment of the video parameters of the key frame image is effected in response to the use of gain, clip, and limit user controls.

The key frame image in the disclosed embodiment is stored as an array of 10-bit luminance values. The 10-bit luminance values are preferably converted to a 1-bit high contrast image prior to vectorizing.

The step of isolating the region of interest in the key frame image also preferably comprises adjusting regions of the key frame image according to geometric characteristics. Adjustment of regions of the key frame image according to geometric characteristics is effected in response to the use of a brush tool by the user.

After the region of interest is isolated and vectorized to obtain a user defined window, the characteristics of the user defined window can be edited to allow the user to adapt the window to the outline of the region of interest. Modification of a user defined window comprises adjusting the number of