How does contiguous work?

Forum|Forum|4 months ago
September 30, 2025
2 replies
387 views

For many years now, I've ran into strange edge case behavior with Magic Wand selecting contiguous. Here's an example where I want to intersect select, resulting in the top and bottom intersections being selected:

With contiguous disabled, all three intersections are selected, as you would expect. With contiguous enabled, only the top intersection is selected for some reason. Changing tolerance doesn't effect anything, and all of the black segments are the exact same color.

If I try to click just outside the current selection, it results in no selection:

Why does this happen?

Windows

mglush

Community Expert

Hi!

The definition of Contiguous actually means sharing a common border, or touching. So, Contiguoulsin this case means that everything that is the same color—and is touching the area you have selected will be added to the selection. When Contiguous is checked it selects only the areas that are similar and touching, and when it is not checked, it selects all areas that are similar to the area you clicked but are not touching.

I hope that helps!

Michelle

Brad @ Roaring Mouse

Community Expert

Contiguous means it will select all matching pixels that are touching/connected. Non-Contiguous would select any matching pixel, touching or not. So when you select the area you did with Contiguous selected, there is no connection of black pixels within that selection, so, yes it would only select the top bar.

gregdAuthor

Known Participant

I'm sorry, I don't understand. If contiguous only selects "touching/connected" pixels, then why does this intersect select result in a disconnected selection?

mglush

Community Expert

Hi!

Here is anothre definiton that might help. This comes from a Google search:

In Photoshop, "contiguous" refers to pixels that are touching or sharing a common border. When a tool with a "contiguous" option, such as the Magic Wand tool,is set to contiguous, it will only select pixels of a similar color that are directly adjacent to each other. If contiguous is unchecked, the tool will select all pixels of the similar color on the entire layer, regardless of whether they are connected.

Here is a video that might help: https://www.youtube.com/watch?v=QKB08u3UXEk

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