Gustave Caillebotte is high in key: pale, luminous, and filled with optical air. Gustave Caillebotte orchestrates warmth above all else - reds, ambers, and siennas take the lead. Muted throughout, the palette achieves its effects through value and temperature rather than chromatic force. The saturated accent, #A4AECA, registers at 7.9% - sparse enough to feel like a deliberate surprise. At 54 units across the value scale, the palette keeps contrast readable without letting it dominate. Palette 4 sits within the larger chromatic argument that Gustave Caillebotte's complete body of work advances.