Image and Video Processing Libraries in Ptolemy II by ... - CiteSeerX

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1 0 -1 √ 2 0 - √ 2 1 0 -1 -1 - √ 2 -1 0 0 0 1 √ 2 1 Figure 3.9: Frei and Chen Horizontal and Vertical Masks 1 0 -1 1 0 -1 1 0 -1 -1 -1 -1 0 0 0 1 1 1 Figure 3.10: Prewitt Horizontal and Vertical Masks 3.4.4 JAIEdgeDetection It is often useful to be able to detect edges in images. A common use of edge detection is to be able to segment an image into different objects. The JAIEdgeDetection uses a gradient based method. The input image is filtered with two different masks. The two intermediate images are squared, added to each other, and then square rooted. There are several built in masks, shown in figures 3.9 to 3.13. The user can choose to input a custom mask by choosing “User Specified” from either or both of the pull down menus, and inputting the appropriate values in the field(s). 3.5 Frequency Domain Processing Traditionally we look at images as a plot of intensity over space. However we can transform these images to plots of magnitude and phase over frequency. 38
3.5.1 JAIDFT 0 0 -1 0 1 0 0 0 0 -1 0 0 0 1 0 0 0 0 Figure 3.11: Roberts Cross Edge Masks 1 0 -1 2 0 -2 1 0 -1 -1 -2 -1 0 0 0 1 2 1 Figure 3.12: Sobel Horizontal and Vertical Masks The Discrete Fourier Transform (DFT) [5] transforms an image from the spatial domain to the frequency domain. Generally, the images contain real data. However, when it is transformed into the frequency domain, each data point is complex (unless the image is symmetric). The number of bands at the output is double the number of bands at the input, alternating between real and imaginary 1 . In the case that the data is complex at the input, the dataNature parameter should be changed to ComplexToComplex. For a single banded image, the Discrete Fourier Transform is defined to be: ⎧ ⎪⎨ X(k1, k2) = ⎪⎩ N1−1 N2−1 n1=0 n2=0 x(n1, n2)e −j(2π/N1)k1n1 e −j(2π/N2)k2n2 , for 0 ≤ n1 ≤ N1 − 1, 0 ≤ n2 ≤ N2 − 1 0, otherwise The JAIDFT actor uses a 2 dimensional Fast Fourier Transform (FFT). This corresponds to an increase in image size to the next power of two in each dimension unless that dimension is a power of two itself. 1 Note that while the number of bands could have stayed the same and the data type of the image could be a new data structure, the internal data types supported are all subclasses of the Number class. The Number class currently has no subclass that handles complex numbers. 39
Page 1: Image and Video Processing Librarie
Page 4 and 5: 3.4.2 JAIBoxFilter . . . . . . . .
Page 6 and 7: List of Figures 1.1 Screenshot of V
Page 9 and 10: Acknowledgements The following proj
Page 11 and 12: Chapter 1 Introduction 1.1 Ptolemy
Page 13 and 14: We decided that there was a need fo
Page 15 and 16: of the bands. The values in an imag
Page 17 and 18: Figure 2.1: Non JAI Image Processin
Page 19 and 20: Figure 3.1: The JAI actor library i
Page 21 and 22: P1 #comments 10 10 1001001110 10010
Page 23 and 24: 3.1.2 JAIConstant The JAIConstant a
Page 25 and 26: JAIPNGWriter The JAIPNGWriter diffe
Page 27 and 28: Figure 3.5: An image about to under
Page 29 and 30: Reflect 5 4 4 5 6 6 5 2 1 1 2 3 3 2
Page 31 and 32: sponds to a shift upwards. A value
Page 33 and 34: images in this report were scaled u
Page 35 and 36: Figure 3.7: An example of how to se
Page 37: Figure 3.8: Mask shapes for median
Page 41 and 42: 3.5.3 JAIMagnitude, JAIPhase The JA
Page 43 and 44: 3.8.3 DoubleMatrixToJAI The DoubleM
Page 45 and 46: Figure 4.2: A simple model showing
Page 47 and 48: Figure 4.5: The initial guess. Figu
Page 49 and 50: Figure 4.9: The image after fifteen
Page 51 and 52: Figure 4.12: The image after being
Page 53 and 54: Figure 4.14: Median Filtering on a
Page 55 and 56: Chapter 5 Video Processing Platform
Page 57 and 58: Chapter 6 JMF Actor Library The fol
Page 59 and 60: 6.1.4 ColorFinder The ColorFinder a
Page 61 and 62: Chapter 7 Video Processing Examples
Page 63 and 64: Chapter 8 Future Work Sun has recen
Page 65 and 66: Chapter 9 Appendix The following is
Page 67 and 68: * @param name The name of this acto
Page 69 and 70: } if((data[i][j] > min) && (data[i]

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