rgb2gray using cuda Simple rgb2gray implementation on 256x256 image

ashwinashok9111993@gmail.com in.linkedin.com/pub/ashwin-ashok/54/183/b5b/ [[!table header="no" class="mointable" data=""" License of this example: | Public Domain Date: | 2014-06-26 PyCUDA version: | 2013.1.1 """]]

#!python 

__author__ = 'ashwin'

import pycuda.driver as drv
import pycuda.tools
import pycuda.autoinit
from pycuda.compiler import SourceModule
import numpy as np
import scipy.misc as scm
import matplotlib.pyplot as p

mod = SourceModule \
    (
        """
#include<stdio.h>
#define INDEX(a, b) a*256+b

__global__ void rgb2gray(float *dest,float *r_img, float *g_img, float *b_img)
{

unsigned int idx = threadIdx.x+(blockIdx.x*(blockDim.x*blockDim.y));

  unsigned int a = idx/256;
  unsigned int b = idx%256;

dest[INDEX(a, b)] = (0.299*r_img[INDEX(a, b)]+0.587*g_img[INDEX(a, b)]+0.114*b_img[INDEX(a, b)]);


}

"""
    )

a = scm.imread('Lenna.png').astype(np.float32)
print a
r_img = a[:, :, 0].reshape(65536, order='F')
g_img = a[:, :, 1].reshape(65536, order='F')
b_img = a[:, :, 2].reshape(65536, order='F')
dest=r_img
print dest
rgb2gray = mod.get_function("rgb2gray")
rgb2gray(drv.Out(dest), drv.In(r_img), drv.In(g_img),drv.In(b_img),block=(1024, 1, 1), grid=(64, 1, 1))

dest=np.reshape(dest,(256,256), order='F')


p.imshow(dest)
p.show()