white thin border when making a mask

[hendy_5450]

how do I avoid this white thin line which I get each time I create a mask on an image in illustrator.

[Sameer K]

Hey, @hendy_5450. Welcome to the Photoshop Community. I'll help you figure this out. 

The UI is from Photoshop. How did you create the mask for the layer that has the mule? Does this happen with all layers? 

In most cases, you can use the Brush tool & draw with Black, or white and point at the mask layer to hide or reveal part of the image via masking. Please head here to get started with masking workflows: https://adobe.ly/3XuIlnA

Let me know how it goes. Thanks!

Sameer K

(Type '@' and type my name to mention me when you reply)

[hendy_5450]

yes,
that what i've been doing for the past ten years,
no other option to get the border away in the first place?

[c.pfaffenbichler]

The Layer Mask of the Layer »donkey« seems to have been created imprudently in two ways: 

• Firstly it apparently started with Reveal All instead of Reveal Selection or Hide All, meaning that transformations can result in semi-transparent pixels on the edges. 

• Secondly the Mask is applied to a Smart Object instead of in the Smart Object, meaning that repeated transformations in the containing document would degrade it. 

[hendy_5450]

thank you for this information.

Would you be able to show me where I and how I can change these settings?

[c.pfaffenbichler]

Are you referring to the comment on how the Mask was started? 

If so keep in mind that how a Layer Mask will create »new« content (for example when the Layer is moved or transformed or the Canvas is extended) depend on its original creation. 

• Adding a Layer Mask without a Selection in the Layers Panel will provide a white Layer Mask, filling or painting it black will hide the layer on the canvas but the Mask’s off-canvas-content is/will be white. 

So moving it will result in white sections appearing – which may not be a problem in some cases, but in others (if the Layer itself has off-canvas-content, if resampling happens, …) it can cause unintended regions of the Layer to become visible. 

• If a Layer Mask is based on a Selection its off-canvas-content will be black, so even if the Layer extends beyond the canvas and it is scaled no unintended regions should become visible. 

[c.pfaffenbichler]

One way to adress this kind of Layer Masks is

• to load it as a Selection and

• intersect that with a manual (rectangular) Selection that includes all the relevant parts of the Layer

• delete the original Layer Mask 

• Layer > Layer Mask > Reveal Selection 

Edit: In the screenshots I applied the Layer Style »Stroke« to highlight the unintended, visible pixels.