Problems with aliasing around selections

Question

My question addresses artifacts resulting from selections.

In the first image, I simply drew a selection rectangle with zero feather. (Anti-alias was grayed-out.) I then used alt-backspace to fill the selection with the foreground color. The edges of the filled selection are perfectly smooth.

Then, I used the pen tool to draw a path, converted the path to a selection (feather radius = 0, anti-aliased checked), then used content aware fill to fill-in the area. The edges of the filled area are (1) not smooth like the original rectangle and (2) are substantially different from one another. The edge furthest to the right shows the most obvious jagged edge.

The second image shows a path, converted to a selection, then filled with the content-aware fill command. Notice the slight jagged edge and white line.

These images are shown at high magnification. However, the artifacts are visible at Print View. More to the point, I would just like to know what causes this aliasing (if that’s what it is) and how to avoid it. Any explanation would be much appreciated.alias.jpg

Hannah Nicollet · Answer

Hi @Doc_Pit @Sameer K

This is a workflow issue. I'll explain below.

Thanks!
Hannah Nicollet
QE, Photoshop

What's Causing the Artifacts

Anti-aliasing Creates Partial Transparency:

When you convert a path to selection with anti-aliasing enabled, Photoshop creates partially selected pixels along the edge (typically 50% or varying opacity)

These edge pixels are designed to create smooth curves on solid backgrounds

Content-Aware Fill + Partial Selection = Artifacts:

Content-Aware Fill synthesizes new pixels based on surrounding content

When operating on partially selected edge pixels, it tries to fill them proportionally

The algorithm may not produce consistent results for these semi-transparent edge pixels

This can lead to:

Jagged appearance

White/light halos (unfilled partial pixels)

Inconsistent edges around the same selection

Why Edges Vary:

Content-Aware Fill is analyzing different surrounding content at each edge

The algorithm's synthesis differs based on local context

Partial selection opacity interacts unpredictably with the content generation

How to Avoid These Artifacts

Option 1: Use feathering instead of anti-aliasing

Set anti-alias to OFF, use feather radius of 0.5-1px instead

This may provide better blending for content-aware operations

Option 2: Expand/contract selection

After converting path to selection, use Select → Modify → Expand by 1px before filling

Or use Contract to ensure clean boundaries

Option 3: Use different fill methods for anti-aliased selections

Content-Aware Fill works better with hard-edged selections

For anti-aliased selections, consider using a cloning or healing brush manually along edges after fill

Option 4: Post-process the edges

Fill with Content-Aware first (anti-alias off)

Then manually blend edges with blur or smudge tools if needed

Hi @Doc_Pit @Sameer K This is a workflow issue. I'll explain below.Thanks! Hannah NicolletQE, PhotoshopWhat's Causing the Artifacts

How to Avoid These Artifacts

Sign up

To post, reply, or follow discussions, please sign in with your Adobe ID.

Sign in to Adobe Community

To post, reply, or follow discussions, please sign in with your Adobe ID.

Scanning file for viruses.

This file cannot be downloaded

Hi @Doc_Pit @Sameer K

This is a workflow issue. I'll explain below.

Thanks!
Hannah Nicollet
QE, Photoshop

What's Causing the Artifacts