diff --git a/src/helpers/cm/ColorManagement.hpp b/src/helpers/cm/ColorManagement.hpp
index e970ff592..ecde9396d 100644
--- a/src/helpers/cm/ColorManagement.hpp
+++ b/src/helpers/cm/ColorManagement.hpp
@@ -89,6 +89,7 @@ namespace NColorManagement {
     }
     inline std::string tfToString(eTransferFunction tf) {
         switch (tf) {
+            case CM_TRANSFER_FUNCTION_LINEAR: return "TF:INTERNAL LINEAR NOT NORMALISED";
             case CM_TRANSFER_FUNCTION_BT1886: return "TF:BT1886";
             case CM_TRANSFER_FUNCTION_GAMMA22: return "TF:GAMMA22";
             case CM_TRANSFER_FUNCTION_GAMMA28: return "TF:GAMMA28";
@@ -400,6 +401,17 @@ namespace NColorManagement {
         .primaries        = NColorPrimaries::BT709,
         .luminances       = {.min = 0, .max = 10000, .reference = 80},
     });
+
+    // For internal use only
+    // not normalised to 0.0 - 1.0
+    // luminance values should be set to default SDR settings in SDR mode and to output settings in HDR mode
+    // keep srgb primaries to avoid conversions for image exports
+    static const auto LINEAR_NN_IMAGE_DESCRIPTION = CImageDescription::from(SImageDescription{
+        .transferFunction = NColorManagement::CM_TRANSFER_FUNCTION_LINEAR,
+        .primariesNameSet = true,
+        .primariesNamed   = NColorManagement::CM_PRIMARIES_SRGB,
+        .primaries        = NColorPrimaries::BT709,
+    });
 }
 
 template <typename CharT>
diff --git a/src/render/shaders/glsl/cm_helpers.glsl b/src/render/shaders/glsl/cm_helpers.glsl
index 0c7d3d510..ae4b63ae8 100644
--- a/src/render/shaders/glsl/cm_helpers.glsl
+++ b/src/render/shaders/glsl/cm_helpers.glsl
@@ -127,6 +127,7 @@ vec3 tfST240(vec3 color) {
 
 vec3 toLinearRGB(vec3 color, int tf) {
     switch (tf) {
+        case CM_TRANSFER_FUNCTION_LINEAR: return color;
         case CM_TRANSFER_FUNCTION_EXT_LINEAR: return color;
         case CM_TRANSFER_FUNCTION_ST2084_PQ: return tfInvPQ(color);
         case CM_TRANSFER_FUNCTION_GAMMA22: return pow(max(color, vec3(0.0)), vec3(2.2));
@@ -179,7 +180,7 @@ vec3 fromLinearRGB(vec3 color, int tf) {
 }
 
 vec4 fromLinear(vec4 color, int tf) {
-    if (tf == CM_TRANSFER_FUNCTION_EXT_LINEAR)
+    if (tf == CM_TRANSFER_FUNCTION_EXT_LINEAR || tf == CM_TRANSFER_FUNCTION_LINEAR)
         return color;
 
     color.rgb /= max(color.a, 0.001);
@@ -189,6 +190,9 @@ vec4 fromLinear(vec4 color, int tf) {
 }
 
 vec4 fromLinearNit(vec4 color, int tf, vec2 range) {
+    if (tf == CM_TRANSFER_FUNCTION_LINEAR)
+        return color;
+
     color.rgb = (color.rgb - range[0] * color.a) / (range[1] - range[0]); // @gulafaran
     color.rgb /= max(color.a, 0.001);
     color.rgb = fromLinearRGB(color.rgb, tf);
@@ -231,7 +235,8 @@ vec4
     pixColor.rgb *= pixColor.a;
 #else
     pixColor.rgb = convertMatrix * pixColor.rgb;
-    pixColor     = toNit(pixColor, srcTFRange);
+    if (srcTF != CM_TRANSFER_FUNCTION_LINEAR)
+        pixColor = toNit(pixColor, srcTFRange);
     pixColor.rgb *= pixColor.a;
 #if USE_TONEMAP
     pixColor = tonemap(pixColor, dstxyz, maxLuminance, dstMaxLuminance, dstRefLuminance, srcRefLuminance);
diff --git a/src/render/shaders/glsl/constants.h b/src/render/shaders/glsl/constants.h
index bbab5284b..db8b2cc1d 100644
--- a/src/render/shaders/glsl/constants.h
+++ b/src/render/shaders/glsl/constants.h
@@ -1,6 +1,7 @@
 #ifndef CONSTANTS_H
 #define CONSTANTS_H
 //enum eTransferFunction
+#define CM_TRANSFER_FUNCTION_LINEAR     0 // not normalised
 #define CM_TRANSFER_FUNCTION_BT1886     1
 #define CM_TRANSFER_FUNCTION_GAMMA22    2
 #define CM_TRANSFER_FUNCTION_GAMMA28    3