Book Image

OpenCL Programming by Example

Book Image

OpenCL Programming by Example

Overview of this book

Research in parallel programming has been a mainstream topic for a decade, and will continue to be so for many decades to come. Many parallel programming standards and frameworks exist, but only take into account one type of hardware architecture. Today computing platforms come with many heterogeneous devices. OpenCL provides royalty free standard to program heterogeneous hardware. This guide offers you a compact coverage of all the major topics of OpenCL programming. It explains optimization techniques and strategies in-depth, using illustrative examples and also provides case studies from diverse fields. Beginners and advanced application developers will find this book very useful. Beginning with the discussion of the OpenCL models, this book explores their architectural view, programming interfaces and primitives. It slowly demystifies the process of identifying the data and task parallelism in diverse algorithms. It presents examples from different domains to show how the problems within different domains can be solved more efficiently using OpenCL. You will learn about parallel sorting, histogram generation, JPEG compression, linear and parabolic regression and k-nearest neighborhood, a clustering algorithm in pattern recognition. Following on from this, optimization strategies are explained with matrix multiplication examples. You will also learn how to do an interoperation of OpenGL and OpenCL. "OpenCL Programming by Example" explains OpenCL in the simplest possible language, which beginners will find it easy to understand. Developers and programmers from different domains who want to achieve acceleration for their applications will find this book very useful.
Table of Contents (18 chapters)
OpenCL Programming by Example
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Chapter 4. OpenCL Images

In the previous chapter, we discussed the OpenCL buffers, which are the most important OpenCL objects. They represent the handle to the OpenCL device memory. We discussed how to create a buffer, sub-buffer, transfer the host allocated data to the device, and mapping or un-mapping of the OpenCL buffer. The OpenCL buffers provide caching for regular linear buffers only in one dimension. Many OpenCL devices have a texture processor, which can cache pixels in an image which are its neighbor. So providing a separate interface for images is useful, and can be used to enhance the performance of applications.

In this chapter we will discuss the OpenCL image objects, which are also represented by cl_mem.

We will discuss the following topics:

  • Creating image and sampler objects

  • Performing histogram equalization using image objects. Mapping and querying the image objects.

Before we start, we need to mention that not all OpenCL devices support image computations. An OpenCL programmer...