Matlab Image Enhancement Techniques

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Matlab Image Enhancement Techniques

Matlab Image Enhancement Techniques

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  • 1. Matlab:Image enhancement techniques
  • 2. Filtering
    Filtering is a technique for modifying or enhancing an image. Image processing operations implemented with filtering include smoothing, sharpening, and edge enhancement.
  • 3. Filtering an Image with Predefined Filter Types
    The ‘fspecial’ function produces several kinds of predefined filters. After creating a filter with ‘fspecial’, we can apply it directly to our image data using ‘imfilter’.
    • I = imread('moon.tif');
    • 4. h = fspecial('unsharp');
    • 5. I2 = imfilter(I,h);
    • 6. imshow(I), title('Original Image')
    • 7. figure, imshow(I2), title('Filtered Image')
  • Filtering an Image with Predefined Filter Types
  • 8. Filtering an Image with Predefined Filter Types
    • Predefined filters provided by ‘fspecial’
    • 9. average’ Averaging filter
    • 10. 'disk’ Circular averaging filter (pillbox)
    • 11. 'gaussian’ Gaussian lowpass filter
    • 12. 'laplacian’ Approximates the two-dimensional Laplacian operator
    • 13. 'log’Laplacian of Gaussian filter
    • 14. 'motion’ Approximates the linear motion of a camera
    • 15. 'prewitt’ Prewitt horizontal edge-emphasizing filter
    • 16. 'sobel’Sobel horizontal edge-emphasizing filter
    • 17. 'unsharp’Unsharp contrast enhancement filter
  • Image Enhancement
    Image Enhancement Tools
    adapthisteqContrast-limited adaptive histogram equalization (CLAHE)
    decorrstretchApplydecorrelation stretch to multichannel image
    histeqEnhance contrast using histogram equalizationi
    madjustAdjust image intensity values or colormap
    imnoiseAdd noise to image
  • 18. Image Enhancement
    Image Enhancement Tools
    intlutConvert integer values using lookup table
    medfilt22-D median filtering
    ordfilt22-D order-statistic filtering
    stretchlimFind limits to contrast stretch image
    wiener22-D adaptive noise-removal filtering
  • 19. Image Enhancement
    Image Restoration (Deblurring)
    DeconvblindDeblur image using blind deconvolution
    DeconvlucyDeblur image using Lucy-Richardson method
    DeconvregDeblur image using regularized filter
    DeconvwnrDeblur image using Wiener filter
    Edgetaper Taper discontinuities along image edges
    Otf2psf Convert optical transfer function to point-spread function
    Psf2otf Convert point-spread function to optical transfer function
  • 20. Image Enhancement
    Dilation- and Erosion-Based Functions
    Bwhitmiss Logical AND of an image, eroded with one structuring element, and the image's complement, eroded with a second structuring element.
    Imbothat Subtracts the original image from a morphologically closed version of the image. Can be used to find intensity troughs in an image.
  • 21. Image Enhancement
    Dilation- and Erosion-Based Functions
    Imclose Dilates an image and then erodes the dilated image using the same structuring element for both operations.
    Imopen Erodes an image and then dilates the eroded image using the same structuring element for both operations.
    Imtophat Subtracts a morphologically opened image from the original image. Can be used to enhance contrast in an image.
    point-spread function to optical transfer function
  • 22. Dithering
    Dithering changes the colors of pixels in a neighborhood so that the average color in each neighborhood approximates the original RGB color.