ImageProcesser.cs

using UnityEngine;
using UnityEngine.UI;

public class ImageProcesser : MonoBehaviour {

    public ComputeShader shader;
    public RawImage srcImg;
    public RawImage dstImg;

    void Start () {
        int w = srcImg.texture.width;
        int h = srcImg.texture.height;

        var rTex = new RenderTexture(w, h, 0, RenderTextureFormat.ARGBFloat);
        rTex.enableRandomWrite = true;
        rTex.Create();
        dstImg.texture = rTex;

        shader.SetTexture(0, "srcTex", srcImg.texture);
        shader.SetTexture(0, "dstTex", rTex);
        shader.Dispatch(0, w / 32, h / 32, 1);
	}
}