Image editor apps on linux

gimp

professional editing
very hard user interface , requires study and graphical expertise

drawing

gnome desktop app , included in LXM
basic operations such as lines , text , circles etc
simular to the old paint.exe in mw windows

gimp how-to

• to enhance the “blackness” of something scanned :
  menu > Colors- > Levels
  and bring up the levels to make something more uniform in color.

• to remove background :
  ensure backround (chnanel ?) is set to tranparent
  select background
  then use menu >  Layer -> Transparency -> Color To Alpha

you can also use select by color tool.
the first option does not always detect all background , f.i. inside the ‘rounding’ of the letter “d”

This method kind of assumes you’re using a black foreground on a white background, and wouldn’t work for other colour combinations unless you change the last step.

1) Ensure the layer has transparency enabled. To do this, you may need to right click on the layer (Ctrl-l if the list of layers isn’t visible), then click “add alpha channel” if it isn’t greyed out. You can also use the option in the layer menu.
2) Select the “select by color” tool (shift-o).
3) You may want to adjust the tool options, especially the thresold. If you can’t see the tool options, you can add it from the dockable dialogs submenu of the window menu.
4) Click the background.
5) Clear it (press delete on the keyboard, or select clear from the edit menu).
6) (optional) Duplicate the layer using its right click menu or ctrl-shift-d. The set the mode of the new layer to multiply. Then duplicate the new layer and merge it down (from its right click menu). Maybe duplicate it even more times, merging them down unto the layer immediately above the bottom layer. When you’ve done this a couple of times and there’s no white or grey left in the image, you can merge that layer down as well to have the whole foreground on one layer.