Troubleshooting
Why does my image have a halo or colour fringe?
Light or dark fringing around your subject — causes and how to fix it.
What is colour fringing?
Colour fringing (also called colour spill or a halo) appears as a thin ring of colour around your subject that doesn't belong there. Common examples:
- A person photographed against a white wall has a faint white or grey outline
- A pet photographed on green grass has a greenish tinge around their fur
- A product against a blue background has a blue halo around its edges
Why it happens
When you photograph a subject against a coloured background, light from the background reflects onto the edges of the subject and bleeds into those pixels — especially in soft-focus or high-contrast areas like hair. This is called colour spill and it happens during the original photo, before any background removal.
When the AI removes the background, it correctly identifies those edge pixels as belonging to the subject, so it keeps them. But they still carry the background colour mixed into them.
Additionally, in semi-transparent pixels (hair strands, soft edges), the AI's mask value is somewhere between 0 and 1. At lower alpha values, the edge colour becomes more noticeable because less of the true subject colour is visible.
How to fix it: Decontaminate
The Decontaminate setting in Edge Refinement is designed specifically for this problem. It:
- Identifies semi-transparent edge pixels (where mask value is between 0.05 and 0.95)
- Samples nearby fully-opaque pixels to determine the "true" foreground colour
- Works in Lab colour space (perceptually uniform) to shift edge pixel colours toward the true foreground colour
- The shift is proportional to transparency — more transparent pixels get more correction
How to use it:
- Open your processed image in the editor
- Open the Edge Refinement panel
- Toggle Decontaminate on (it defaults to 50% strength)
- Increase strength if you still see fringing; decrease if colours look unnatural
Other fixes
Contract the mask
If the fringe is a hard ring of background colour (not semi-transparent), it may be background pixels that the AI kept. Use Contract in Edge Refinement with a value of 1–3 px to erode those pixels away.
Erase brush
For stubborn patches of background colour that weren't removed by the AI, use the brush tool in Erase mode to manually remove them. Use a soft brush (low hardness) for gradual removal near edges.
Change the preview background
Sometimes what looks like a halo against one background disappears against another. Toggle the preview background in the Background tool to check whether the edge is genuinely problematic or just a contrast effect.
White halos specifically
A white halo is common when the original photo had a white or very light background. Because white was the background, its colour has bled into the edge pixels. Decontaminate helps, but for very strong white spill, you may also want to:
- Use Contract (–1 to –3 px) to clip the bright edge pixels
- Use a soft erase brush along the edges to gradually reduce opacity