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The imFilters module contains various functions for filtering, enhancement, and basic manipulations of grayscale or color images, in 2D and 3D.

Image enhancement, noise removal

   imAdjustDynamic         - Rescale gray levels of image to get better dynamic
   imMeanFilter            - Compute mean value in the neighboorhood of each pixel
   imMedianFilter          - Compute median value in the neighboorhood of each pixel
   imGaussianFilter        - Apply gaussian filter to an image, using separability
   imDirectionalFilter     - Apply and combine several directional filters
   imNormalizeBackground   - Normalize image by removing background estimate

Gradient and Laplacian filters

   imGradient              - Compute gradient magnitude in a grayscale image
   imLaplacian             - Discrete Laplacian of an image
   imHessian               - Compute coefficients of Hessian matrix for each pixel
   imEigenValues           - Image eigen values from second derivatives
   imMorphoGradient        - Morphological gradient of an image
   imMorphoLaplacian       - Morphological laplacian of an image
   imrecerode              - Perform a morphological reconstruction by erosion
   imHConcave              - H-concave transformation of an image
   imHConvex               - H-convex transformation of an image

Geometric filters

   imFlip                  - Flip an image along one of its dimensions
   imRotate90              - Rotate a 3D image by 90 degrees around one image axis
   imAddBorder             - Add a border around a 2D or 3D image
   imTranspose             - Transpose an image (grayscale or RGB)
   subsample               - Subsample an array by applying operation on blocs
   subsamplergb            - Return a sub-sampled version of an rgb image.


   imOtsuThreshold         - Threshold an image using Otsu method
   imImposedWatershed      - Compute watershed after imposition of extended minima

Color and gray-scale conversions

   imOverlay               - Add colored markers to an image (2D or 3D, grayscale or color)
   imSplitChannels         - Split the 3 channels of a 2D or 3D image
   imMergeChannels         - Merge 3 channels to create a 2D or 3D color image
   double2rgb              - Create a RGB image from double values
   angle2rgb               - Convert an image of angles to color image
   imGetHue                - Extract hue of a color image, using rgb2hsv.
   imGray12ToGray8         - Convert a 12 bits gray scale image to 8 bits gray scale

Filters for binary images

   imBoundary              - Compute the boundary image of a binary image
   imFillHoles             - Fill holes in a binary image
   imDistanceMap           - Compute chamfer distance using scanning algorithm
   imDistanceClasses       - Converts a distance map to a label image of regions
   imSkeleton              - Homothopic skeleton of a binary image 
   imLabelSkeleton         - Label skeleton pixels according to local topology
   imChainPixels           - Chain neighbor pixels in an image to form a contour
   imConvexImage           - Compute smallest convex image containing the original pixels
   imDistance              - Distance map computed from a set of points
   imDistance3d            - Create distance image from a set of 3D points

Filters for binary/label images

   label2rgb3d             - Convert a 3D label image to a 3D RGB image
   imKillBorders           - Remove regions on the border of an image
   imAreaOpening           - Remove all regions smaller than a given area
   imAttributeOpening      - Filter regions on a size or shape criterium
   imLargestRegion         - Keep the largest region in a binary or label image
   imCropLabel             - Extract the portion of image that contains the specified label
   imMergeLabels           - Merge regions in a labeled image
   mergeRegions            - Merge regions of labeled image, using inclusion criteria
   imBoundaryIndices       - Find indices of boundary between 2 cells
   imLabelEdges            - Label edges between adjacent regions of labeled image.

Utilities and drawing

   imCreate                - Create a new image with given the size and type
   imCheckerBoard          - Create a checkerboard image from 2 images
   imCheckerboardLabels    - Create a checkerboard label image
   imThumbnail             - Resize an image to bound the size in each direction
   imDrawLine              - Draw a line between two points in the image
   bresenhamLine           - Integer coordinates of a bresenham line
   imDrawText              - Draw some text in an image
   imTpsWarp               - Warp an image using Thin-Plate Splines transform

Indexed images

   imLUT                   - Apply a look-up table (LUT) to a gray-scale image.
   grayFilter              - Compute configuration map of a binary image
   grayHist                - Compute frequencies of configurations in binary images
   createTile              - Create a binary tile (2x2) from its index
   tileIndex               - Return the index of a 2x2 binary tile
   createTile3d            - Create a 3D binary tile (2x2x2) from its index
   tileIndex3d             - Return the index of a 2x2x2 binary tile

Kernels and structuring elements

   ball                    - Generate a ball in a matrix in 2 or 3 dimensions
   gaussianKernel3d        - Create a 3D Gaussian kernel for image filtering
   orientedGaussianKernel  - Oriented Gaussian kernel for directional filtering
   orientedLaplacianKernel - Oriented Laplacian kernel for directional filtering
   cross3d                 - Return a 3D structuring element with cross shape
   intline                 - Integer-coordinate line drawing algorithm.
   strelDisk               - Discrete disk structuring element
   imNeighborhood          - Return the neighborhood of a given pixel