Filter 2D Image Planes

The Filter sub-tab allows the processing of images and the modifying of the original media to fit to the needs of correlation or presentation purposes. Certain colors can be filtered out, and the media can be enhanced by applying the appropriate filters and pixel mapping algorithms.
  1. From the 2D Image Plane tab, click the Filter sub-tab.
  2. Select the type of filter to enable from the Type drop-down menu.
    None No filter options are applied to the image plane.
    Edge Processes the image by looking for "edges" (or sharp changes in color/contrast within the image). The filter replaces the original graphic with outlines where the edges were detected. There are three modes available to use with this filter.
    Note: The edge detection filter requires a color. When edges are detected and replaced with outlines, the color box specifies the new outline color drawn by the filter.
    ColorAlpha Removes all of the pixels from an image that match the criteria specified using the Mode, Color, and optionally the Tolerance field. Essentially this option takes an image with a solid background and makes the background transparent when drawn within HyperView, leaving just the foreground content visible. There are three modes available to use with this filter.
    Note: The color box specifies what background color to look for in the image, so that it can be made transparent.
      Lower right corner of the modeling window.
  3. Select a color, or range of colors, to replace or remove from the Mode drop-down menu.
    This is particularly useful when images contain a background composed of several subtle shades of the same color.
    Note: This option is disabled (grayed out) if no filter type options are selected.
    If an Edge filter type is selected, the following options allow you to specify which edge detection algorithm is to be used:
    Prewitt Calculates the maximum response of a set of convolution kernels to find the local edge orientation for each pixel.
    Laplacian The edge points of an image can be detected by finding the zero crossings of the second derivative of the image intensity. Calculating the second derivative is very sensitive to noise.
    Sobel Calculates the gradient of the image intensity at each point, giving the direction of the largest possible increase from light to dark and the rate of change in that direction. The result shows how "abruptly" or "smoothly" the image changes at that point, and therefore how likely it is that part of the image represents an edge, as well as how that edge is likely to be oriented.
    Tip: The various algorithms behave differently, therefore you may need to experiment in order to see which one generates the best results.
    If a ColorAlpha Type filter type is selected, the following options allow you to select a range of colors to remove:
    Equal Searches for an exact match for the color specified. This option also allows you to specify a search tolerance (using the Tolerance slider bar). The tolerance is multiplied by each of the three RGB color values. The filter will then match colors where each component value is within the target color plus or minus the multiplied tolerance result. For example, if the color gray (RGB 80, 80, 80) is selected with a tolerance setting of 10, the filter will match and remove all colors where the R, G, and B values are greater than 72 and less than 88.
    LesserThan Removes all of the color from the image plane which is darker than the color specified. For example, if the color gray is selected, values less than RGB 80, 80, 80 would be removed.
    GreaterThan Removes all of the color from the image plane which is brighter than the color specified. For example, if the color gray is selected, values greater than RGB 80, 80, 80 would be removed.
  4. Click the Color box and select a new color to filter the colors greater than, less than, or equal to the selected color and intensity.
    Tip: The Edge/Mode/Color options are particularly useful for enhancing the media when viewing analysis models with section cuts. The image filtering options are typically more useful for 3D image planes, as the planes can be positioned in model space close to where the video is projected. If a section cut is applied, or the edges of the model are displayed, the edge filtering removes all inner details from the media to match the outlines of the simulation results.
  5. Select the mipmap mode to be used from the Pixel mapping drop-down menu.
    HyperView employs the use of mipmaps to scale the image in the image plane. When an image plane is rendered, it is typically not the same size (in pixels) as the original. Because of this, the image must be scaled up or down before it is rendered to the screen. Specifying a mipmap mode will determine how the image scaling is performed.
    None Use Linear Interpolation only.
    Nearest1 Use MipMaps and Linear Interpolation.
    Nearest2 Use MipMaps and Linear Interpolation.
    Linear1 Use MipMaps and closest pixel.
    Linear2 Use MipMaps and closest pixel.
    Note: Mipmaps can be used to render the image with improved clarity, however in some cases it may interfere with certain filters (such as the ColorAlpha filter).