Thanks Dénes,
I refer again to my explanatory diagram posted previously in this topic
here, as my views have not changed.
What you have to take into consideration is that the multitude of differences in curvature and angles of certain areas of the aircraft's fuselage/cowling etc is going to give quite different tonal values compared to other areas on the aircraft that are painted in the same colour because of how the reflected light affects what our eyes and the camera sees. Dependent on the light source in each photo we could have a whole range of tonal values that are realistically all the same colour.
The area on the nose that you suggest is colour 1 is mostly affected by the reflection of the light source (sun). Because that particular area of the cowling is curving/facing directly into the sunlight it is reflecting the most light back at our eyes or the camera in this case. Take a look at the same area, but closer to the top of the cowling where it curves away from the direct sunlight. Notice that it gradually starts to get darker and thus closer in tone to the section that you mark as colour number 3... These two splinter segments are the same colour (RLM62 green). It's just the bright reflections from the sun light is affecting how the colour is perceived.
1 = RLM62 (Green)
2 = RLM61 (Brown)
3 = RLM62 (Green) too
4 = RLM63 (Grey)