Select and Mask decontaminate colors issues.

What decontaminate colors does is getting information from inside the subject and fills the edges. I solved my problem following this tutorial, really helpful: How to fix Decontaminate Color issues in Photoshop from Complex Selections in Photoshop Class | CreativeLive

In short:

- use the refine edge and decontaminate colors and choose new layer with mask

- you'll have your cut out

- then have a duplicate of the original image up your cut out

- create a clipping mask with it (so it will only show what's masked on the cut out layer)

- create a mask in that duplicate of the original layer

- now you can choose what you don't want to be affected by the decontaminate colors

Much better to follow the instructions in the tutorial if you're not familiar with clipping masks, but there you go.

Simple answer is do not use decontaminate colors in Select and Mask - it does not work.

If you need to decontaminate - create a new empty layer above the masked layer and clip it to the masked layer. Set the blending mode of this new layer to color.

Now with a soft brush at 25-30% opacity use colour picked up from the image (Alt-Click) and brush around the edges.This will colour using the image colour and cover any contamination from the old background.

In this case though it does not look like you have much , if any, contamination to deal with

Dave

I tried this on a similar image of raspberrries downloaded from Google images. When the mask is disabled, there is a bit more pixelization around the selection edge with this method, though not quite as severe as you have experienced here.(see attached images) I would suggest that is a result of the refining of the edge with the Refine edge brush and using the Decontaminate Colors option, which is going to have a tolerance setting that affects how the edge is rendered. Once the layer mask is created, it appears to recalculate the transition edge, resulting in a smoother, less pixelated selection. I don't see this as a cause for concern.

What is the resolution of your image? This may be a significant factor in the edge pixelization.

Why are you using decontaminate with a white background??? It's meant for green screens - the green gets everywhere. This image looks nice and neutral - no color spill anywhere.