How to remove/detect lone pixels?

[SaKnoi]

I'm trying to find pixels which are next to others, and removing pixels with no neighbours seems to be the best solution. Is it possible to either delete lone pixels/highlight continuous runs of pixels using some function?

[c.pfaffenbichler · Accepted solution]

This might work: 

• duplicate the Layer thrice,

• move one copy 1 px to the right,

• aother 1 px down, 

• convert the three Layers to a Smart Object, 

• Layer > Smart Objects > Stack Mode > Median, 

• Filter > Other > Minimum aith 1px and Roundness, 

• set the Smart Object’s Blend Mode to Screen. 

[Kukurykus]

I don't know what, but something I did wrong. My result is same as source file.

[c.pfaffenbichler]

What does the Smart Object (containing the three layers, two of which are offset by one pixel) with the Stack Mode »Median« look like for you? 

[Kukurykus]

So I have background, that I pressed Ctrl-J, Ctrl-J and Ctrl-J on. A top layer I moved of 1 px to right, next layer 1 px to down. Then selected 3 first layers (so without background) and made SO from. Then from Stack Mode clicked Median (from SO in Layer) that I had to do in latest Ps as in CS6, Stack Mode was grayed.

At this point the only difference between SO and BG is that SO pixels are moved of 1 px to right.

[davescm]

That is clever 🙂

It does pick up two pixels touching corner to corner in this direction

But misses the same in this direction - so would need a second run

Still very clever though.

Dave

[r-bin]

It is not clear why this is necessary.
And if the pixels are white or just different colors?

[r-bin]

There is an attempt to access individual pixels and the possibility of changing them using a script.

https://community.adobe.com/t5/photoshop/get-index-of-each-pixel/m-p/10022899?page=1

EDIT: In that topic, all the scripts are kind of broken. Forget it.

[r-bin]

If you have black(gray\color) pixels and absolute white backgound then you can do this.

Make two copies of the original layer.

Apply to one of the copies Custom Filter

0 0 0 0 0
0 1 1 1 0
0 1 0 1 0
0 1 1 1 0

0 0 0 0 0
scale: 8 offset: 0

Using magic wand with

tol = 0, antial = off, cont = off

select white (255,255,255) on this layer.
If it's hard to find white, find a single pixel on the original, it will definitely turn white.

Turn off \ delete this layer. Switch to another copy. Fill the selection with white.

You can check the result by putting the layer to Difference blend mode or turning layer on\off.

Pixels at the very edges are not deleted. It is necessary to expand the canvas by 1 pixel at least with white filling.

UPD. To increase accuracy, you can replace in filter 1 with 256, and in scale 8 with 2048.

[Kukurykus]

I created my own dots this time, and all worked, with c_pfaffenbichler method too 🙂