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

Querying image objects


Similar to all OpenCL objects, image objects can also be queried using the clGetImageInfo function. In the previous chapter, we discussed the clGetMemObjectInfo function, which was used to query the OpenCL cl_mem object. This API can be used to determine if the cl_mem object is of type CL_MEM_OBJECT_BUFFER or one of the image types specified by cl_image_desc.image_type argument while creating the image object.

Once you know that the cl_mem object is for an OpenCL image object, you can retrieve information about the image using the clGetImageInfo function.

cl_int clGetImageInfo (cl_mem image,cl_image_info param_name,size_t param_value_size,void *param_value,size_t *param_value_size_ret)

The different param_name values which can be given are as follows:

  • CL_IMAGE_FORMAT: It gives the image format descriptor when the image was created

  • CL_IMAGE_ELEMENT_SIZE: It gives the size of a pixel element in the image

  • CL_IMAGE_ROW_PITCH: It gives the size of a row in bytes

  • CL_IMAGE_SLICE_PITCH...