diff --git a/src/table/opengl_shader.h b/src/table/opengl_shader.h
--- a/src/table/opengl_shader.h
+++ b/src/table/opengl_shader.h
@@ -9,25 +9,33 @@
 
 /** @file opengl_shader.h OpenGL shader programs. */
 
-/** Vertex shader that just passes colour and tex coords through. */
-static const char *_vertex_shader_direct[] = {
+/** Vertex shader that positions a sprite on screen.. */
+static const char *_vertex_shader_sprite[] = {
 	"#version 110\n",
+	"uniform vec4 sprite;",
+	"uniform vec2 screen;",
 	"attribute vec2 position, colour_uv;",
 	"varying vec2 colour_tex_uv;",
 	"void main() {",
+	"  vec2 size = sprite.zw / screen.xy;",
+	"  vec2 offset = ((2.0 * sprite.xy + sprite.zw) / screen.xy - 1.0) * vec2(1.0, -1.0);",
 	"  colour_tex_uv = colour_uv;",
-	"  gl_Position = vec4(position, 0.0, 1.0);",
+	"  gl_Position = vec4(position * size + offset, 0.0, 1.0);",
 	"}",
 };
 
-/** GLSL 1.50 vertex shader that just passes colour and tex coords through. */
-static const char *_vertex_shader_direct_150[] = {
+/** GLSL 1.50 vertex shader that positions a sprite on screen. */
+static const char *_vertex_shader_sprite_150[] = {
 	"#version 150\n",
+	"uniform vec4 sprite;",
+	"uniform vec2 screen;",
 	"in vec2 position, colour_uv;",
 	"out vec2 colour_tex_uv;",
 	"void main() {",
+	"  vec2 size = sprite.zw / screen.xy;",
+	"  vec2 offset = ((2.0 * sprite.xy + sprite.zw) / screen.xy - 1.0) * vec2(1.0, -1.0);",
 	"  colour_tex_uv = colour_uv;",
-	"  gl_Position = vec4(position, 0.0, 1.0);",
+	"  gl_Position = vec4(position * size + offset, 0.0, 1.0);",
 	"}",
 };
 
@@ -76,3 +84,65 @@ static const char *_frag_shader_palette_
 	"  colour = texture(palette, idx);",
 	"}",
 };
+
+
+/** Fragment shader function for remap brightness modulation. */
+static const char *_frag_shader_remap_func = \
+	"float max3(vec3 v) {"
+	"  return max(max(v.x, v.y), v.z);"
+	"}"
+	""
+	"vec3 adj_brightness(vec3 colour, float brightness) {"
+	"  vec3 adj = colour * (brightness > 0.0 ? brightness / 0.5 : 1.0);"
+	"  vec3 ob_vec = clamp(adj - 1.0, 0.0, 1.0);"
+	"  float ob = (ob_vec.r + ob_vec.g + ob_vec.b) / 2.0;"
+	""
+	"  return clamp(adj + ob * (1.0 - adj), 0.0, 1.0);"
+	"}";
+
+/** Fragment shader that performs a palette lookup to read the colour from an 8bpp texture. */
+static const char *_frag_shader_rgb_mask_blend[] = {
+	"#version 110\n",
+	"#extension GL_ATI_shader_texture_lod: enable\n",
+	"#extension GL_ARB_shader_texture_lod: enable\n",
+	"uniform sampler2D colour_tex;",
+	"uniform sampler1D palette;",
+	"uniform sampler2D remap_tex;",
+	"uniform bool rgb;",
+	"uniform float zoom;",
+	"varying vec2 colour_tex_uv;",
+	"",
+	_frag_shader_remap_func,
+	"",
+	"void main() {",
+	"  float idx = texture2DLod(remap_tex, colour_tex_uv, zoom).r;",
+	"  vec4 remap_col = texture1D(palette, idx);",
+	"  vec4 rgb_col = texture2DLod(colour_tex, colour_tex_uv, zoom);",
+	"",
+	"  gl_FragData[0].a = rgb ? rgb_col.a : remap_col.a;",
+	"  gl_FragData[0].rgb = idx > 0.0 ? adj_brightness(remap_col.rgb, max3(rgb_col.rgb)) : rgb_col.rgb;",
+	"}",
+};
+
+/** GLSL 1.50 fragment shader that performs a palette lookup to read the colour from an 8bpp texture. */
+static const char *_frag_shader_rgb_mask_blend_150[] = {
+	"#version 150\n",
+	"uniform sampler2D colour_tex;",
+	"uniform sampler1D palette;",
+	"uniform sampler2D remap_tex;",
+	"uniform float zoom;",
+	"uniform bool rgb;",
+	"in vec2 colour_tex_uv;",
+	"out vec4 colour;",
+	"",
+	_frag_shader_remap_func,
+	"",
+	"void main() {",
+	"  float idx = textureLod(remap_tex, colour_tex_uv, zoom).r;",
+	"  vec4 remap_col = texture(palette, idx);",
+	"  vec4 rgb_col = textureLod(colour_tex, colour_tex_uv, zoom);",
+	"",
+	"  colour.a = rgb ? rgb_col.a : remap_col.a;",
+	"  colour.rgb = idx > 0.0 ? adj_brightness(remap_col.rgb, max3(rgb_col.rgb)) : rgb_col.rgb;",
+	"}",
+};