GPU Implementation of Satellite Image Filtering using OpenCL             Institute for Geoinformatics Advanced processing ...
Objective• Efficient edge detection method for remote  sensing imageries.• implementation of image filtering on  programma...
Application• The HOST executes the code written as usual,  using C++.• The DEVICES execute OpenCL code.• Use specific Open...
ApplicationOpenCL Code: 1 - Create the OpenCL code using OpenCL language;Host Code: 2 - Create program using C++; 3 - Impo...
Main OpenCL API Commands• Memory allocation via API   – clCreateBuffer• Accessing device memory via API   – clEnqueueWrite...
Method• Landsat imageries  – Bands with high contrast, e.g. Band 4• Image Convolution  – 3X3 Filtering Mask convolves over...
Sobel Filter• 2-D anisotropic measure of the 1st spatial  derivative of an image.
Sobel filter• consists of two kernels (Masks) which detect  horizontal and vertical changes in an image• The 3x3 Sobel ker...
Sobel filter
Laplacian filter  2-D isotropic measure of the 2nd spatial  derivative of an image.
Sobel Filter Output Image
Sobel Filter Output Image
GPU vs CPU performanceSobel FilterLaplacian Filter
Open Issue• Applying Image smoothing and contrast  enhancement before/during filtering
Gpu implementation of satellite image filtering
Gpu implementation of satellite image filtering
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Gpu implementation of satellite image filtering

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Gpu implementation of satellite image filtering

  1. 1. GPU Implementation of Satellite Image Filtering using OpenCL Institute for Geoinformatics Advanced processing of geospatial data- GPU, Grid and Cloud computing Ermias Beyene Tesfamariam 15 July 2010
  2. 2. Objective• Efficient edge detection method for remote sensing imageries.• implementation of image filtering on programmable GPU using the openCL language• Comparison of different algorithms (Sobel vs. Laplacian) for their efficiency and quality
  3. 3. Application• The HOST executes the code written as usual, using C++.• The DEVICES execute OpenCL code.• Use specific OpenCL compiler for the CPU & for the GPU (ATI Stream).• The OpenCL API has functions to identify devices, compile programs, send and receive information and run OpenCL program on the chosen device.
  4. 4. ApplicationOpenCL Code: 1 - Create the OpenCL code using OpenCL language;Host Code: 2 - Create program using C++; 3 - Import the data to be processed; 4 - Use the OpenCL API to transfer data to the devices; 5 - Use the OpenCL API to call executions; 6 - Retrieve processed data.
  5. 5. Main OpenCL API Commands• Memory allocation via API – clCreateBuffer• Accessing device memory via API – clEnqueueWriteBuffer – clEnqueueReadBuffer
  6. 6. Method• Landsat imageries – Bands with high contrast, e.g. Band 4• Image Convolution – 3X3 Filtering Mask convolves over the image• Sobel Algorithm• Laplacian Algorithm
  7. 7. Sobel Filter• 2-D anisotropic measure of the 1st spatial derivative of an image.
  8. 8. Sobel filter• consists of two kernels (Masks) which detect horizontal and vertical changes in an image• The 3x3 Sobel kernels are: – Horizontal – Vertical
  9. 9. Sobel filter
  10. 10. Laplacian filter 2-D isotropic measure of the 2nd spatial derivative of an image.
  11. 11. Sobel Filter Output Image
  12. 12. Sobel Filter Output Image
  13. 13. GPU vs CPU performanceSobel FilterLaplacian Filter
  14. 14. Open Issue• Applying Image smoothing and contrast enhancement before/during filtering
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