Select inside/outside of a border

Question

This seems like a basic feature, but I'm missing it somehow. I have the the outline of a state with a discrete colorful border.

I'd like to select the border AND the inner contents so I can produce something like this (sloppily done here with the Lasso)

I've tried selecting the entire border using the fuzzy select (magic wand) or select by color but this only gives me the border itself.

In the Selection menu, I can invert the selection, but that grabs everything.

How can I select all the contents inside a selected region?

Answer 1

This is a job for the quick mask feature. I allows you to paint on the selection itself as if it were the image -

So, after selecting the border itself with the magic wand as you did above, click on the small "hidden" button to the left of the horizontal scroll bar. That shows a red tinted translucent representation of your selection itself, and all painting you do will affect it - it is a grayscale drawable, so full white (255) means "fully selected" and black (0) means "unselected" (although the representation on this view is inverted: selected areas are shown as transparent, unselected as opaque). Then, just use the bucket-fill tool to fill u the outside (or inside) of your selection with "White" (Which will render the trnaslucent tint transparent), revert back to normal editing by clicking on the quickmask again - and you are done.

It certainly does take much fewer steps than Kylemit's answer.

Answer 2

Here's a simple way to let the fuzzy select drive the entire process.

TLDR: grab the border and invert the selection, then fill the outside and paste over the original image.

Steps By Step:

1. Original
   
2. Fuzzy Select Border
   
3. Select > Invert + Cut
   
4. Bucket Fill Tool Outside
   
5. Select All + Copy
   
6. Undo until Original Image + Paste
   
7. Layer > Anchor Layer
   
8. Fuzzy Select Outside + Cut
   

Answer 3

You can utilize multiple selection tools for a single selection. Try color selecting the stroke with the Magic Wand (adjust the tolerance at the top to refine the selection) then using any of the other selection tools like the Rectangle Marquee tool for example, hold shift and select the area within.

Holding Shift (while dragging a selection) with a selection tool adds the new selection to the current selection. Holding Alt subtracts from the current selection.

Answer 4

Assuming that you don't have the border on a separate layer:

1. Use the fuzzy select (magic wand tool) to select the interior. Click and hold on any white/grey point inside, then drag until most of the inside is selected.

2. Use Select>Grow set to 4px or so. This will partially select the red border and also consume the small unselected areas in the middle.

3. With the magic wand still active, shift+click on the red border.

Hope that helps!

Answer 5

On selecting the red line we will end up with an outer and an inner selection of the area enclosed.

This big "hole" can be removed using an external script Remove Holes (from Selection) designed to just do that.

Also see How can I select the convex hull of an existing selection? for an example.

Answer 6

Can't comment yet so I'll make a new answer combining Takkat and sojmoore. I had an outline in an image which i wanted to select, followed by the entire interior as described in this question. The outline had been created in the original image by some overlay arithmetic, so the outline color was modulated slightly by the varying color of the pixels beneath it (there's probably a single word for that in graphics processing but I don't know it). As a result, I could select much of the outline by Shift clicking with the select by Color, on different pixels of the outline... up to a point. Eventually it was not possible to tell in the selection editor if i was adding anything or not. At this point, The Remove Holes script did not work. In order for it to work, I first had to add some Fuzzy Selection of contiguous regions by color, inside the outline selection. Only then did the remove holes script work (perfectly I might add).