diff --git a/doc/includes/references.h b/doc/includes/references.h
index c0d5de37..14ce8845 100644
--- a/doc/includes/references.h
+++ b/doc/includes/references.h
@@ -1303,6 +1303,9 @@ struct mjrContext_ {              // custom OpenGL context
 
   // framebuffer
   int     currentBuffer;          // currently active framebuffer: mjFB_WINDOW or mjFB_OFFSCREEN
+
+  // pixel output format
+  int     readPixelFormat;        // default color pixel format for mjr_readPixels
 };
 typedef struct mjrContext_ mjrContext;
 typedef enum mjtButton_ {         // mouse button
diff --git a/include/mujoco/mjrender.h b/include/mujoco/mjrender.h
index 8c68f230..2e095d40 100644
--- a/include/mujoco/mjrender.h
+++ b/include/mujoco/mjrender.h
@@ -149,6 +149,9 @@ struct mjrContext_ {              // custom OpenGL context
 
   // framebuffer
   int     currentBuffer;          // currently active framebuffer: mjFB_WINDOW or mjFB_OFFSCREEN
+
+  // pixel output format
+  int     readPixelFormat;        // default color pixel format for mjr_readPixels
 };
 typedef struct mjrContext_ mjrContext;
 
diff --git a/src/render/render_context.c b/src/render/render_context.c
index 849137fd..8b763b7f 100644
--- a/src/render/render_context.c
+++ b/src/render/render_context.c
@@ -1602,6 +1602,9 @@ void mjr_makeContext_offSize(const mjModel* m, mjrContext* con, int fontscale,
   while ((err = glGetError())) {
     mju_warning_i("OpenGL error 0x%x in or before mjr_makeContext", err);
   }
+
+  // set default color pixel format for mjr_readPixels
+  con->readPixelFormat = GL_RGB;
 }
 
 
diff --git a/src/render/render_gl2.c b/src/render/render_gl2.c
index 0c252fbc..7ea8f91b 100644
--- a/src/render/render_gl2.c
+++ b/src/render/render_gl2.c
@@ -153,7 +153,7 @@ void mjr_readPixels(unsigned char* rgb, float* depth,
     // read rgb and depth
     if (rgb) {
       glReadPixels(viewport.left, viewport.bottom, viewport.width, viewport.height,
-                   GL_RGB, GL_UNSIGNED_BYTE, rgb);
+                   con->readPixelFormat, GL_UNSIGNED_BYTE, rgb);
     }
     if (depth) {
       glReadPixels(viewport.left, viewport.bottom, viewport.width, viewport.height,
diff --git a/unity/Runtime/Bindings/MjBindings.cs b/unity/Runtime/Bindings/MjBindings.cs
index 51f88e24..97f891ab 100644
--- a/unity/Runtime/Bindings/MjBindings.cs
+++ b/unity/Runtime/Bindings/MjBindings.cs
@@ -2282,6 +2282,7 @@ public unsafe struct mjrContext_ {
   public int windowStereo;
   public int windowDoublebuffer;
   public int currentBuffer;
+  public int readPixelFormat;
 }
 
 [StructLayout(LayoutKind.Sequential)]