I didn't test the x11/wayland check yet, but feel free to use it and report back.

  #!/bin/bash 
  # Dependencies: tesseract-ocr imagemagick 
  # on gnome: gnome-screenshot 
  # on kde: spectacle
  # on x11: xsel
  # on wayland: wl-clipboard

  die(){
  notify-send "$1"
  exit 1
  }
  cleanup(){
  [[ -n $1 ]] &&  rm -rf "$1"
  }

  SCR_IMG=$(mktemp)  || die "failed to take screenshot"

  # shellcheck disable=SC2064
  trap "cleanup '$SCR_IMG'" EXIT

  notify-send "Select the area of the text" 
  if  which "spectacle" &> /dev/null
  then
    spectacle -r -o "$SCR_IMG.png" || die "failed to take screenshot"
  else
    gnome-screenshot -a -f "$SCR_IMG.png" || die "failed to take screenshot"
  fi

  # increase image quality with option -q from default 75 to 100
  mogrify -modulate 100,0 -resize 400% "$SCR_IMG.png"  || die "failed to convert image"
  #should increase detection rate

  tesseract "$SCR_IMG.png" "$SCR_IMG" &> /dev/null || die "failed to extract text"
  if [ "$XDG_SESSION_TYPE" == "wayland" ]
  then 
  wl-copy < "$SCR_IMG.txt" || die "failed to copy text to clipboard"
  else
  xsel -b -i  < "$SCR_IMG.txt" || die "failed to copy text to clipboard"
  fi
  notify-send "Text extracted"
  exit

Formatting

  #!/bin/bash
  # Dependencies: tesseract-ocr imagemagick scrot xsel

  IMG=`mktemp`
  trap "rm $IMG*" EXIT

  scrot -s $IMG.png -q 100
  # increase image quality with option -q from default 75 to 100

  mogrify -modulate 100,0 -resize 400% $IMG.png
  #should increase detection rate

  tesseract $IMG.png $IMG &> /dev/null
  cat $IMG.txt | xsel -bi
  notify-send "Text copied" "$(cat $IMG.txt)"

  exit

[0] https://github.com/microsoft/PowerToys

I just really don't know, it feels like it's, uh, subpar. Isn't it? I never seriously worked in that domain, but it somehow felt to me in the 2019, that with all recent advancements in computer vision, text recognition must be essentially a solved problem. I'd expect it to be better than human. Yet I still cannot accurately convert a low-res scan (scan! not even a photo!) of a receipt with tesseract, especially if it isn't in English. Maybe I just cannot properly use it?

Myself I tried it probably 10-15 years ago on scanned scientific papers (decent scanning quality). The results were disappointing. The manual postprocessing required was not much less than typing it directly. So tesseract became a synonym of "not worth trying" to me.

Maybe things have improved over the years, so I should give it a new try. (No particular use case at the moment, but those tend to appear occasionally.)

Being a Flatpak app, it will require desktop portals to fully work. That said, it worked absolutely fine out of the box for me with my existing xdg-desktop-portal-wlr setup. So, it should work fine in any X11 or Wayland setup where you have an xdg-desktop-portal setup that supports the Screenshot API.

The results are mixed, but not bad by any means. Cleanly readable text comes out mostly fine with maybe only whitespace issues and the occasional error, which makes this still potentially very useful for copying text out of error dialogs and whatnot. (Though, I've found that on Linux, error dialogs are far more likely to have selectable text in the first place. And on Windows, standard MessageBox responds to Ctrl+C.)

I like the author.