sharpen.metal

kernel void sharpen(
                   texture2d<float, access::write> outTex [[texture(0)]],
                   texture2d<float, access::read> inTex [[texture(1)]],
                   uint2 gid [[thread_position_in_grid]]) {
    float4 c = float4(0.0, 0.0, 0.0, 1.0);
    //隣接ピクセルを使用して色を決定するためのパラメータ
    float weight[3][3] = {
        {0, -1, 0},
        {-1,  5, -1},
        {0, -1, 0}
    };
    for (int u=0; u<3; u++) {
        for (int v=0; v<3; v++) {
            float3 a = inTex.read(gid + uint2(u-1, v-1)).rgb;
            c.rgb += weight[u][v] * a;
        }
    }
    outTex.write(c.rgba, gid);
}