“Select by color” and “draw path from selection” in Inkscape?

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I imported an image to Inkscape. Now I’d like to select all those regions that have the same (or to a certain degree similar) color. From this selection I’d like to draw a path (to which I can add a border or background color).

I’d like to generate an object, that has the exact dimensions as a certain region in an Image. How can I do this with Inkscape? I couldn’t find one of the functions above, but I’m sure there in a easy way to do this.

EDIT:
The answer by Takkat looked quite promising. Unfortunately, although I turned off all smothening options, the paths do not follow the colours precisely:

Before:

before

After:

after

The same things are happening, when I use other scan-modes. I couldn’t find an option that follows the border of the enlarged pixels,…

Answer

The way to generate objects by color in Inkscape would be to trace the bitmap to vector paths.

This is how I selected the color yellow of the sunflowers to add a white border to all sunflowers.

  1. File > Import bitmap (embed) to the Inkscape canvas:

    enter image description here Wikimedia

  2. Select the bitmap and choose Path > Trace Bitmap…:

    • In Mode tab choose Colors, and Smooth. Do not Stack scans.
    • Reduce number of Scans until the desired object is clear (here I used 6)

  3. Choose Object > Ungroup.

  4. Delete all objects of unwanted colors until only a single color is left over (imported bitmap is removed here only to better demonstrate the effect):

    enter image description here

  5. Select the single yellow object to adjust Stroke or Fill settings to desired values (here I applied a 6 Pixel white stroke):

    enter image description here

For a higher precision of the trace (down to pixel size) we may have to scale up our source bitmap, depending on its content. The example below show a detail from above image linearly scaled by 1000% to reveal pixel blocks (left). Then I traced this image (right) with 12 color scans and without any path optimization (i.e. disable all, Smooth, Suppress speckles, Smooth corners, and Optimize Path):

enter image description here

We now can select all yellow objects, create a union object from these, and adjust fill and stroke (here a 10 px white stroke):

enter image description here

Note: Tracing large upscaled bitmaps will result in an immense amount of data. Your computer will need enough RAM to handle this.

Attribution
Source : Link , Question Author : R_User , Answer Author : Takkat

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