An impossible selection?

[terrypin]

After an hour or so trying in vain to make the following selection, I suspect I'm attempting the impossible?

I want to select the thin yellow country border (mainly Italy/Austria) that I've captured as a JPG from Google Earth. (So that I can thicken it and change its colour.)

Here are three (downloadable) screenshots:

https://www.dropbox.com/s/1lk6pen7l9hr1 ... .jpg?raw=1

https://www.dropbox.com/s/w4784rwjgms2h ... d.jpg?dl=0

https://www.dropbox.com/s/dfbbflo6ppl6x ... 2.jpg?dl=0

EDITED a few minutes later
Aaagh - so obvious! I'll leave the post rather than delete it, in case anyone else ever makes the same mistake. Namely capturing as a JPG! After saving as a PSPimage the selection was simple. (Except, oddly, for a pixel or two in the Alps which were not the pure yellow of the rest.)

[terrypin]

Another puzzle arose when I came to fill the expanded selection. Despite having opacity at 100 and mode at None, I had to repeatedly click until I got a solid yellow.

My screenshot illustrates this:

https://www.dropbox.com/s/qhqpv7hqkn71l ... mage?raw=1

[Jean-Luc]

You need to play with the Tolerance.

[JoeB]

You need to play with the Tolerance.

Tolerance isn't available for the modes None and All Opaque.

I seem to recall once running into the same issue but can't remember what caused it. However, while waiting for a proper response you could try this workaround. Once you have your selection completed and before filling it you could create a new transparent raster layer. With that layer active try flood filling the selection. If that works, once filled you can then merge the layers.

[LeviFiction]

Okay, according to the sample image it took a lot of fills to make the line look solid and full, each clicking was slightly transparent and it built up. Correct?

Looks like you might have a feather/soft-edge to your selection. Have you tried using Unfeather?

I just tried this, with 98% success (some parts didn't want to be selected but the rest went very smoothly)
My steps were:
1) Select All
2) Selections -> Modify -> Select Color Range (selected the brightest yellow on the image, tolerance of 100, softness of 20, subtract color range)
3) Selections -> Invert Selection
4) selections -> Modify -> Expand (by 3 pixels)
5) Use fill tool set to bright yellow, Match mode none, opacity 100, blend mode normal, sample merged deselected.

[terrypin]

Thanks Levi, I think that’s it. Bedtime here so will get on the case again tomorrow.

[terrypin]

I repeated the exercise first thing today and conclude that, as usual, the devil is in the detail. Before trying the suggestions from either LeviFiction or JoeB I started from scratch with this capture:
https://www.dropbox.com/s/8gluetoe06rev ... mage?raw=1

And here's a zoomed in section:
https://www.dropbox.com/s/5vua2ftcaisu0 ... mage?raw=1
from which it's clear that there are many 'near-yellow' pixels.

So (as Jean-Luc implied, although in a different context) I need to take care over tolerance when making the selection. I started with Magic Wand settings of Replace, RGB value, Tolerance=20, no Feather, no Anti-alias. (Later I aim to experiment with the impact of those. As mentioned, I think I had Feather set to 1 or 2 yesterday.) My first click selected only a short selection so I increased Tolerance to 30 and stepped my way through the remaining border. I suppose I could have increased Tolerance above 30 and achieved the full selection more quickly, but then I'd have risked straying outside.

I think that initial careful selection was the critical step. I was then able to use the Fill tool set to None, Opacity=100 and fill the border with solid yellow (or any other colour).

I then realised that, unlike yesterday, I had not yet expanded the selection by 1 or 2 pixels. So I then did so and filled the border again with one click. Here's the satisfactory result:
https://www.dropbox.com/s/h6gtwdwozmskr ... mage?raw=1

Greatly appreciate all the help, learned a lot once again!

[Jean-Luc]

How is the initial yellow line made ?
Could it be painted on a transparent layer above the map ? If so, it could be easier to select.

[terrypin]

How is the initial yellow line made ?
Could it be painted on a transparent layer above the map ? If so, it could be easier to select.

As described in my opening post: captured from Google Earth.

One thing I’ll try next time is to apply one of my darker GE map overlays before the capture.