Lab: DFT of Simple Images

[Exercises] [Workspace]

Purpose: The purpose this experiments is demostrate some DFT of Simple Images.

Activities:

1. Sinusoidal
   1. Use the Sinusoid operator and generate object of 128x128 with attributes "Num. along Width" equal 7 and "Num. along Height" equal 7. Normalize with Normalize operator. Extract its FFT seting Unity scaling and Log (Magnitude + 1) using FFT and Magnitudes operators, normalize this result. Inset the two results normalized and display using Inset and Display Image operators.

      1. Glyphs:Input/Output:Generate Data: Sinusoid

      2. Glyphs:Data Manip:Data Conversion: Normalize

      3. Glyphs:Arithmetic:Linear Transforms: FFT

      4. Glyphs:Arithmetic:Complex Operators: Magnitudes

      5. Glyphs:Data Manip:Size & Region Operators: Inset

      6. Glyphs:Visualization:Non-Interactive Display: Display Image

2. Rectangle
   1. Use the Constant operator and generate object constant with "Width" equal 7, "Height" equal 8, and change "Real Constant Level" to 1. Padding of a data object create change its attributes "Padded Width" to 128, "Padded Height" to 128, "Width Offset" to (128-7)/2, "height Offset" to (128-8)/2. Now proceed how item 1.

      1. Glyphs:Input/Output:Generate Data: Constant

      2. Glyphs:Data Manip:Size & Region Operators: Pad

3. Gaussian
   1. Use the 2D Gaussian operator and generate gaussian function image of 128x128, seting attributes "Peak Location along Width (X)" to 64, "Peak Location along Height (Y)" to 64, "Variance along Width" to 4*4, and "Variance along Height" to 4*4. Now proceed how item 1.

      1. Glyphs:Input/Output:Generate Data: 2D Gaussian

4. Impulses
   1. Use the Impulse operator and generate object size of 128x128, change attributes "Num. along Width" to 128/7, "Num. along Height" to 128/8, "Width Spacing" to 7, "Height Spacing" to 8, and "Real Value of Impulse" to 1. Select data type to "Unsigned Byte". In this case use to FFT operator Scale output by 1/sqrt(N) per transform axis. Now procced how item 1.

      1. Glyphs:Input/Output:Generate Data: Impulse

Khoros Workspace
Execute the visual program c5s4dft-simple-images.wk