dolphin/Data/User/Shaders/16bit.txt

uniform sampler2D samp9;

out vec4 ocol0;
in vec2 uv0;

uniform vec4 resolution;

void main()
{
  //Change this number to increase the pixel size.
  float pixelSize = 3;

  float red   = 0.0;
  float green = 0.0;
  float blue  = 0.0;
  
  vec2 pos = floor(uv0 * resolution.xy / pixelSize) * pixelSize * resolution.zw;
  
  vec4 c0 = texture(samp9, pos);

  if (c0.r < 0.1)
    red = 0.1;
  else if (c0.r < 0.20)
    red = 0.20;
  else if (c0.r < 0.40)
    red = 0.40;
  else if (c0.r < 0.60)
    red = 0.60;
  else if (c0.r < 0.80)
    red = 0.80;
  else
    red = 1.0;

  if (c0.b < 0.1)
    blue = 0.1;
  else if (c0.b < 0.20)
    blue = 0.20;
  else if (c0.b < 0.40)
    blue = 0.40;
  else if (c0.b < 0.60)
    blue = 0.60;
  else if (c0.b < 0.80)
    blue = 0.80;
  else
    blue = 1.0;

  if (c0.g < 0.1)
    green = 0.1;
  else if (c0.g < 0.20)
    green = 0.20;
  else if (c0.g < 0.40)
    green = 0.40;
  else if (c0.g < 0.60)
    green = 0.60;
  else if (c0.g < 0.80)
    green = 0.80;
  else
    green = 1.0;
  
  ocol0 = vec4(red, green, blue, c0.a);
}