Sky Segmentation & Mask Preparation for Sky Replacement

Project overview

A sky segmentation dataset was prepared for an AI-powered sky replacement pipeline. The client supplied property images captured under poor weather and lighting, where a dull or unattractive sky reduced the overall visual appeal of the photograph.

The objective was to isolate the sky region accurately by generating refined binary masks, so that a realistic sky, such as a blue sky with white clouds, could be inserted while the rest of the scene was preserved. Property and outdoor images were taken as input and refined binary sky masks with alpha channel extraction were produced as output.

Work performed

• Reviewed and organised the client-provided image dataset.
• Generated sky segmentation masks with a paid, pre-trained segmentation model.
• Extracted the alpha channel from each segmented output and converted it into a binary mask.
• Processed the binary masks through a mask refiner to remove imperfections.
• Improved boundary accuracy around buildings, trees, rooftops and other complex edges.
• Carried out quality assurance so that every mask was suitable for sky replacement.
• Delivered the processed outputs according to client requirements.

What made it hard

• Handling complex boundaries around trees, buildings and utility poles.
• Fine detail had to be preserved while segmentation artefacts were removed.
• Producing clean masks for images captured under different lighting and weather conditions.
• Maintaining consistent mask quality across the entire dataset.

Result

High-quality refined sky masks were prepared that enabled realistic sky replacement in property images. The processed outputs noticeably improved the appearance of outdoor scenes by allowing attractive skies, such as a blue sky with white clouds, to be inserted seamlessly.

Final deliverable

Refined binary sky masks were generated from the client-provided images using a sky segmentation model, alpha channel extraction and mask refinement. The final outputs were optimised for realistic AI-based sky replacement while the natural appearance of the original scenes was preserved.