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OpenCL 1.2 read/write image data

I'm creating an Image2d object on the host using the flag CL_MEM_READ_WRITE. This image is the output of one kernel and I want it to be used as an input to a different kernel. I'm also using cl_image_format = {CL_INTENSITY, CL_FLOAT};

Is this possible in OpenCL 1.2? I've read nowhere that says you can't do this, yet when I try my second kernel returns all zeros, but no error.

I've also tried using clEnqueueCopyImage to copy the output of the first kernel to a different Image2d (also created using CL_MEM_READ_WRITE) and using that as input to the second kernel, but that also does not work.

I've verified the output of my first kernel is correct.

Thanks for any insight.

Solution

  • Yes, the output image from one kernel can be used as input to a subsequent kernel.

    As long as the image is CL_MEM_READ_WRITE it can either read __read_only or __write_only in a kernel in OpenCL 1.x.

    OpenCL 2.0 further allows images to be __read_write but special rules must be followed (such as barriers) to get correct results.

    For more information on read/write image, please see https://software.intel.com/en-us/articles/using-opencl-20-read-write-images

    Don't try to cheat (OpenCL - Pass image2d_t twice to get both read and write from kernel?)