diff --git a/plugins/GSdx/GSDeviceOGL.h b/plugins/GSdx/GSDeviceOGL.h
index 532ded2a63fab..f413971c6e3de 100644
--- a/plugins/GSdx/GSDeviceOGL.h
+++ b/plugins/GSdx/GSDeviceOGL.h
@@ -485,7 +485,7 @@ class GSDeviceOGL : public GSDevice
 
 	struct {
 		GLuint vs;		// program object
-		GLuint ps[10];	// program object
+		GLuint ps[11];	// program object
 		GLuint ln;		// sampler object
 		GLuint pt;		// sampler object
 		GSDepthStencilOGL* dss;
diff --git a/plugins/GSdx/GSTextureCacheOGL.cpp b/plugins/GSdx/GSTextureCacheOGL.cpp
index 206cd705c2ee7..743103c7d2c70 100644
--- a/plugins/GSdx/GSTextureCacheOGL.cpp
+++ b/plugins/GSdx/GSTextureCacheOGL.cpp
@@ -67,12 +67,12 @@ void GSTextureCacheOGL::Read(Target* t, const GSVector4i& r)
 
 		case PSM_PSMZ24:
 			fmt = GL_R32UI;
-			ps_shader = 11;
+			ps_shader = 10;
 			return;
 
 		case PSM_PSMZ16:
 			fmt = GL_R16UI;
-			ps_shader = 12;
+			ps_shader = 10;
 			return;
 
 		default:
diff --git a/plugins/GSdx/res/glsl/convert.glsl b/plugins/GSdx/res/glsl/convert.glsl
index b84778de5ec83..bea451dd1a3b5 100644
--- a/plugins/GSdx/res/glsl/convert.glsl
+++ b/plugins/GSdx/res/glsl/convert.glsl
@@ -58,7 +58,7 @@ in SHADER
 #define PSin_t (PSin.t)
 
 // Give a different name so I remember there is a special case!
-#ifdef ps_main1
+#if defined(ps_main1) || defined(ps_main10)
 layout(location = 0) out uint SV_Target1;
 #else
 layout(location = 0) out vec4 SV_Target0;
@@ -137,6 +137,15 @@ void ps_main1()
 }
 #endif
 
+#ifdef ps_main10
+void ps_main10()
+{
+	vec4 c = sample_c();
+	const float exp2_32 = exp2(32.0f);
+	SV_Target1 = uint(exp2_32 * c.r);
+}
+#endif
+
 #ifdef ps_main7
 void ps_main7()
 {
diff --git a/plugins/GSdx/res/glsl_source.h b/plugins/GSdx/res/glsl_source.h
index 6368f3164fdeb..e5f4392d89e0f 100644
--- a/plugins/GSdx/res/glsl_source.h
+++ b/plugins/GSdx/res/glsl_source.h
@@ -83,7 +83,7 @@ static const char* convert_glsl =
 	"#define PSin_t (PSin.t)\n"
 	"\n"
 	"// Give a different name so I remember there is a special case!\n"
-	"#ifdef ps_main1\n"
+	"#if defined(ps_main1) || defined(ps_main10)\n"
 	"layout(location = 0) out uint SV_Target1;\n"
 	"#else\n"
 	"layout(location = 0) out vec4 SV_Target0;\n"
@@ -133,18 +133,25 @@ static const char* convert_glsl =
 	"#ifdef ps_main1\n"
 	"void ps_main1()\n"
 	"{\n"
-	"    vec4 c = sample_c();\n"
-	"	// Color is RGBA8\n"
+	"	// Input Color is RGBA8\n"
 	"\n"
 	"	// We want to output a pixel on the PSMCT16* format\n"
+	"	// A1-BGR5\n"
 	"\n"
 	"#if 0\n"
+	"	// For me this code is more accurate but it will require some tests\n"
+	"\n"
+	"    vec4 c = sample_c() * 255.0f + 0.5f; // Denormalize value\n"
 	"\n"
-	"    highp uvec4 i = uvec4(255.0f * c * vec4(1/32.0f, 4.0f, 64.0f, 512.0f));\n"
+	"    highp uvec4 i = uvec4(c * vec4(1/32.0f, 4.0f, 64.0f, 512.0f)); // Shift value\n"
 	"\n"
 	"    SV_Target1 = (i.x & uint(0x001f)) | (i.y & uint(0x03e0)) | (i.z & uint(0x7c00)) | (i.w & uint(0x8000));\n"
 	"\n"
 	"#else\n"
+	"	// Old code which is likely wrong.\n"
+	"\n"
+	"    vec4 c = sample_c();\n"
+	"\n"
 	"	c.a *= 256.0f / 127.0f; // hm, 0.5 won't give us 1.0 if we just multiply with 2\n"
 	"\n"
 	"	highp uvec4 i = uvec4(c * vec4(uint(0x001f), uint(0x03e0), uint(0x7c00), uint(0x8000)));\n"
@@ -155,6 +162,15 @@ static const char* convert_glsl =
 	"}\n"
 	"#endif\n"
 	"\n"
+	"#ifdef ps_main10\n"
+	"void ps_main10()\n"
+	"{\n"
+	"	vec4 c = sample_c();\n"
+	"	const float exp2_32 = exp2(32.0f);\n"
+	"	SV_Target1 = uint(exp2_32 * c.r);\n"
+	"}\n"
+	"#endif\n"
+	"\n"
 	"#ifdef ps_main7\n"
 	"void ps_main7()\n"
 	"{\n"