White lines around cut out layers

[adam]

When cutting out a part of a flat image to create a new layer this generates a white line around the new layer. This is particularly noticible if I use paste in place.

I have attached two images before where the image is flat and the next where I have cut out the chair and the footstool. I would expect as the chair and footstool were part of the image before and cutting them out and pasting them in place would still create a seamless image but there are white lines as seen in the second image.

Is there some setting I have not changed that is causing this or something I am doing wrong?

[rich2005]

Have to confess, I do not really get-it from your description. The light border usually occurs with a fuzzy select around a shape on a light coloured background. A border of semi-transparent light pixels (anti-aliasing) remains. The fix for this is shrink the selection to exclude the border before copy / paste.

How did you make your initial selection and from where ?

From what is given:
I made a temporary duplicate layer so I can see the edge https://i.imgur.com/8s7V5x4.jpg
Into the original layer with the selection https://i.imgur.com/7z29Tq0.jpg
Copy / paste back in. https://i.imgur.com/3xF4Etp.jpg - but dark background on dark background so any stray pixels not showing

If you give a few more details then you will get a better answer

There is also this advice https://www.gimp-forum.net/Thread-Backgr...r-graphics

[adam]

Hi Rich,

Sorry if I was not completely clear, this seems to only happen on some images and I am not sure why, hence the question.

My workflow for this image was as follows ( a workflow I use a lot):

Open --> use the paths tool create a path --> paths to selection --> cut --> paste as new layer in place

Expected result - same visually looking image (just one part or more is on another layer)

Actual result - the cut out and pasted in place parts have white borders around.

I wasn't using the fuzzy select tool in this occassion. I do get fuzzy borders with that tool but I clean them up,  I was not expecting these fuzzy edges with the simple cut and paste commands, or is this to be expected? I hope the above makes more sense?

----

I am not sure what you are doing in your sequence, what is the duplicate layer and the dark background on dark background parts doing? This is not a workflow that I have used before. 

The background colour swap thing is useful tip , thank you! Not sure how that would work for this workflow though.

[sallyanne]

Make sure your image has an alpha channel before feathering

[rich2005]

@adam

You should have no problem with your workflow. It might be the copy-cut that is the problem. Like sallyanne says give the image an alpha channel and I advise not a cut but a copy.

Edit: It is the cut that is the issue, because the layer has no alpha channel (transparency) when you cut, the semi-transparent border pixels take the background colour, white but could be whatever colour is set. The pasted back-in-place edge is semi-transparent so the overlap shows white-ish.

Using a path is a great way to get your selection. Using your 'original' I get this





Sorry, all the gory detail, so 5 minute duration. Have a look and see where we differ.

[adam]

@rich2005 @sallyanne

Super awesome! Thank you for all your help! I am blown away to have a whole video explaining the issue! I can see now that the issue is cutting from an non-alpha channel image. I can now adjust work flow to avoid this.