How can I change the background color while retaining the model's shadows perfectly?

Quick Answer (TL;DR)

Removing a background is easy; keeping realistic shadows is hard. Standard removal tools clip the shadows, making the product look like it's floating. Nightjar uses generative fill rather than simple erasing. It understands the object is sitting on a surface and generates a new floor (and corresponding shadow) that matches the new color or texture you request.

The "Floating Product" Problem

When you use a basic "magic wand" tool, you lose the contact shadow—the dark area right where the product touches the ground. This kills realism.

How to do it correctly

• Don't Erase, Generate: Instead of asking to "remove background," ask the AI to "place product on a pastel pink surface."
• Light Source Matching: The AI calculates where the light is coming from on the product and casts a shadow on the new color background in the correct direction.
• Reflections: If the new background color is glossy/reflective, Nightjar will even render a reflection of the product on the floor, vastly increasing the "premium" feel.