GNU.WIKI: The GNU/Linux Knowledge Base

  [HOME] [PHP Manual] [HowTo] [ABS] [MAN1] [MAN2] [MAN3] [MAN4] [MAN5] [MAN6] [MAN7] [MAN8] [MAN9]

  [0-9] [Aa] [Bb] [Cc] [Dd] [Ee] [Ff] [Gg] [Hh] [Ii] [Jj] [Kk] [Ll] [Mm] [Nn] [Oo] [Pp] [Qq] [Rr] [Ss] [Tt] [Uu] [Vv] [Ww] [Xx] [Yy] [Zz]


NAME

       read_imagef_(1D) - Do an element lookup in the 1D image object,
       returning floating-point values.

       float4 read_imagef(image1d_t image, sampler_t sampler, int coord);

       float4 read_imagef(image1d_t image, sampler_t sampler, float coord);

       float4 read_imagef(image1d_t image, int coord);

       float4 read_imagef(image1d_buffer_t image, int coord);

       float4 read_imagef(image1d_array_t image, int2 coord);

       float4 read_imagef(image1d_array_t image, sampler_t sampler,
                          float4 coord);

FUNCTIONS TO READ 1D IMAGES AND IMAGE ARRAYS

       For forms that take image1d_t, use coord to do an element lookup in the
       1D image object specified by image.

       For forms that take image1d_array_t, use coord.x to do an element
       lookup in the 1D image identified by coord.y in the 1D image array
       specified by image.

       The samplerless read image functions behave exactly as the
       corresponding read image functions that take integer coordinates and a
       sampler with filter mode set to CLK_FILTER_NEAREST, normalized
       coordinates set to CLK_NORMALIZED_COORDS_FALSE and addressing mode to
       CLK_ADDRESS_NONE.

       read_imagef returns floating-point values in the range [0.0... 1.0] for
       image objects created with image_channel_data_type set to one of the
       predefined packed formats or CL_UNORM_INT8 or CL_UNORM_INT16.

       read_imagef returns floating-point values in the range [-1.0... 1.0]
       for image objects created with image_channel_data_type set to
       CL_SNORM_INT8, or CL_SNORM_INT16.

       read_imagef returns floating-point values for image objects created
       with image_channel_data_type set to CL_HALF_FLOAT or CL_FLOAT.

       The read_imagef calls that take integer coordinates must use a sampler
       with filter mode set to CLK_FILTER_NEAREST, normalized coordinates set
       to CLK_NORMALIZED_COORDS_FALSE and addressing mode set to
       CLK_ADDRESS_CLAMP_TO_EDGE, CLK_ADDRESS_CLAMP or CLK_ADDRESS_NONE;
       otherwise the values returned are undefined.

       Values returned by read_imagef for image objects with
       image_channel_data_type values not specified in the description above
       are undefined.

NOTES

       General information about the read_image* functions follows.

       The built-in functions defined in this section can only be used with
       image memory objects. An image memory object can be accessed by
       specific function calls that read from and/or write to specific
       locations in the image.

       Image memory objects that are being read by a kernel should be declared
       with the accessQualifiers(3clc) qualifier.  write_image calls to image
       memory objects declared with the accessQualifiers(3clc) qualifier will
       generate a compilation error. Image memory objects that are being
       written to by a kernel should be declared with the
       accessQualifiers(3clc) qualifier.  read_image calls to image memory
       objects declared with the accessQualifiers(3clc) qualifier will
       generate a compilation error.  read_image and write_image calls to the
       same image memory object in a kernel are not supported.

       The read_image calls returns a four component floating-point, integer
       or unsigned integer color value. The color values returned by
       read_image are identified as x, y, z, w where x refers to the red
       component, y refers to the green component, z refers to the blue
       component and w refers to the alpha component.

       The following table describes the mapping of the number of channels of
       an image element to the appropriate components in the float4, int4 or
       uint4 vector data type for the color values returned by
       read_image{f|i|ui} or supplied to write_image{f|i|ui}. The unmapped
       components will be set to 0.0 for red, green and blue channels and will
       be set to 1.0 for the alpha channel.

              ┌──────────────────────────┬────────────────────────────┐
              │      Channel Order       │ float4, int4 or uint4      │
              │                          │ components of channel data │
              ├──────────────────────────┼────────────────────────────┤
              │       CL_R, CL_Rx        │     (r, 0.0, 0.0, 1.0)     │
              ├──────────────────────────┼────────────────────────────┤
              │          CL_A            │     (0.0, 0.0, 0.0, a)     │
              ├──────────────────────────┼────────────────────────────┤
              │      CL_RG, CL_RGx       │      (r, g, 0.0, 1.0)      │
              ├──────────────────────────┼────────────────────────────┤
              │          CL_RA           │      (r, 0.0, 0.0, a)      │
              ├──────────────────────────┼────────────────────────────┤
              │     CL_RGB, CL_RGBx      │       (r, g, b, 1.0)       │
              ├──────────────────────────┼────────────────────────────┤
              │CL_RGBA, CL_BGRA, CL_ARGB │        (r, g, b, a)        │
              ├──────────────────────────┼────────────────────────────┤
              │      CL_INTENSITY        │        (I, I, I, I)        │
              ├──────────────────────────┼────────────────────────────┤
              │      CL_LUMINANCE        │       (L, L, L, 1.0)       │
              └──────────────────────────┴────────────────────────────┘

       A kernel that uses a sampler with the CL_ADDRESS_CLAMP addressing mode
       with multiple images may result in additional samplers being used
       internally by an implementation. If the same sampler is used with
       multiple images called via read_image{f|i|ui}, then it is possible that
       an implementation may need to allocate an additional sampler to handle
       the different border color values that may be needed depending on the
       image formats being used. These implementation allocated samplers will
       count against the maximum sampler values supported by the device and
       given by CL_DEVICE_MAX_SAMPLERS. Enqueuing a kernel that requires more
       samplers than the implementation can support will result in a
       CL_OUT_OF_RESOURCES error being returned.

SPECIFICATION

       OpenCL Specification[1]

SEE ALSO

       imageFunctions(3clc)

AUTHORS

       The Khronos Group

COPYRIGHT

       Copyright © 2007-2011 The Khronos Group Inc.
       Permission is hereby granted, free of charge, to any person obtaining a
       copy of this software and/or associated documentation files (the
       "Materials"), to deal in the Materials without restriction, including
       without limitation the rights to use, copy, modify, merge, publish,
       distribute, sublicense, and/or sell copies of the Materials, and to
       permit persons to whom the Materials are furnished to do so, subject to
       the condition that this copyright notice and permission notice shall be
       included in all copies or substantial portions of the Materials.

NOTES

        1. OpenCL Specification
           page 292, section 6.12.14 - Image Read and Write Functions



  All copyrights belong to their respective owners. Other content (c) 2014-2018, GNU.WIKI. Please report site errors to webmaster@gnu.wiki.
Page load time: 0.087 seconds. Last modified: November 04 2018 12:49:43.