Image in GUI is darker than on a plane

I want to use some images as buttons and backgrounds but their color tone or contrast seems to be different even though they come from the same file in my project folder (meaning they should have the same settings, right?).

To show what I mean, I took some random image and placed them side by side. The left image is on a plane, the right is drawn through GUI.DrawTexture. When I open the image in say windows photo viewer, the left image’s colours/tones are correct and the right is too dark.

Code for drawing the GUI is just (C#)

public Texture2D image;

void OnGUI()
{
    GUI.DrawTexture(New Rect(someX,0,Screen.width, Screen.Height), image);
}

I don’t have another computer or a friend I can ask to try and reproduce this (without hassle and a lot of waiting)

I found a proper solution for this.

Use EditorGUI.DrawPreviewTexture. It seems to me that GUI.DrawTexture should be deprecated since EditorGUI.DrawPreviewTexture also allows for a custom material.

Using it like so, worked for me and made the texture draw is if it was unlit:

EditorGUI.DrawPreviewTexture(new Rect(0.0f, 0.0f, 100, 100), myTexture);

This answer merges the three comments I made

This could be related to the lighting model used. Shader for GUI cannot receive illumination from lights in the scene.

IMHO the problem is that GUI.DrawTexture does not offer control on the internal shader used. That is one reason why I don’t use the GUI methods for drawing my HUD. Instead I prefer to make my own quad and use a second camera (orthographic) for the GUI.