1000x800大小的图像无法正常渲染

I need to render an image of size 1000x800 on an android device. If i create width and height of 2x2 image is rendered properly. If anything above this size that is 2x2 my image is not displayed properly, texture appears to be grabage. I am using Opengl ES 2.0. I tried setting orthoM matrix in various ways but above 2x2 width and height everything appears bad. How do i map image pixel to device pixel. I created meshgrid for image which starts from (0,0) and goes uptil width and height. That means to say my coordinate doesnt start at the centere where as it starts at top left corner. I need to render an image of size 1000x800 on a