Sobel Filter Design Example

This example implements a simple Sobel filter in Open Computing Language (OpenCLTM). The example contains a single work-item kernel that implements a Sobel operator to detect edges in an input RGB image (8 bits per component) and outputs a monochrome image. The kernel code is instructive, showing how to efficiently describe a sliding-window line buffer. This is a technique that can be used in many other image filtering applications.

This example also has an interactive host application. The host application allows you to choose between displaying the input or filtered image. The edge detection threshold can also be dynamically adjusted and the selected threshold value is passed to the OpenCL kernel as a parameter.

Sobel Filter Performance

Image Size Frames per Second
1920x1080130

Features

  • Visual and interactive host
  • Efficient 2D sliding-window line buffers
  • Single work-item kernel

Downloads

The design example provides source code for the OpenCL device (.cl) as well as the host application. For compiling the host application, the Linux package includes a Makefile and the Windows package includes a Microsoft Visual Studio 2010 project.

The following downloads are provided for this example (v17.0 example comping soon):

The use of this design is governed by, and subject to, the terms and conditions of the hardware reference design license agreement.

Software and Hardware Requirements

This design example requires the following tools:

  • Intel® FPGA Software v16.1 or later
  • Intel® FPGA SDK for OpenCL™ v16.1 or later
  • On Linux: GNU Make and gcc
  • On Windows: Microsoft Visual Studio 2010
  • Host application requires Open Graphics Library (OpenGL) for display

To download the Intel design tools, visit the OpenCL download page. The requirements for the underlying operating system are the same as those of the Intel FPGA SDK for OpenCL.

Sobel Filter Display

OpenCL and the OpenCL logo are trademarks of Apple Inc. used by permission by Khronos.

* Product is based on a published Khronos Specification, and has passed the Khronos Conformance Testing Process. Current conformance status can be found at www.khronos.org/conformance.

Design Examples Disclaimer

These design examples may only be used within Altera Corporation devices and remain the property of Altera. They are being provided on an “as-is” basis and as an accommodation; therefore, all warranties, representations, or guarantees of any kind (whether express, implied, or statutory) including, without limitation, warranties of merchantability, non-infringement, or fitness for a particular purpose, are specifically disclaimed. Altera expressly does not recommend, suggest, or require that these examples be used in combination with any other product not provided by Altera.