Show Screenshot image on GUI, linear color space , Need help

I made a script to take screenshot and display the image on GUI. But since my project has to use linear color space, when I use the screenshot image as Texture2D on GUI, the image become dark.
is there any solution for this problem?

    // to capture screenshot//
    Texture2D screenCap;
     screenCap = new Texture2D(1024,1024, TextureFormat.RGB24, false);
    screenCap.ReadPixels(new Rect(Screen.width /2 - 512, Screen.height /2 - 512 ,1024,1024), 0, 0);

// to see  captured image void OnGUI//
GUI.DrawTexture(new Rect(100, 100, 300, 300), screenCap);

For the record, just switch to Debug mode if your render texture is created as an asset in the Editor.
Then check the SRGB parameter.

Go back to Normal mode and change any option (eg: Color Format) to make SRGB apply.