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

Image representation


We represent an image in a digital computer by a matrix of pixels (picture element). For an image containing only two colors (possibly black and white), the pixel can be a bi-level (Boolean) field with true (1) meaning white, and false (0) meaning black. One of the file formats for representing this kind of image is the PBM (Portable Bit Map) file format. In this file format, each pixel is represented by one bit. If the image is of size WIDTH * HEIGHT, then each row is WIDTH bits, packing eight pixels into a byte, with don't care bits to fill out the last byte in the row. There are HEIGHT number of such rows.

Now let's consider a gray scale image. The number of distinct gray scale values that can be represented by a pixel depends on the number of Bits Per Pixel (bpp). For 8 bpp, 256 gray scale values can be represented. In this case, pixel values can vary from 0 to 255. These pixel values are often referred to as pixel intensity levels. So a pixel may be represented as...