opengl es - Improve texture resolution in GLSL fragment shader -

is there way icrease, or improve resolution of texture using glsl fragment shader processing? let's say, have 512x424 px source image, , want have 1024x848 px result, smooth pixels.

update. under "improvement" mean enlarging using sort of resampling algorithm.

1. create fbo, attach large destination texture desired dimensions
2. render "full-screen" textured quad small source texture bound