2017. június 22.

Scanimage produces unreadable lineart image with default settings

Compared to Ubuntu 12.04 and the default settings for Canon LiDE 210 flatbed scanner changed in Ubuntu 16.04.

The default result of a Lineart scan was unacceptable (unreadable).
It turned out, that --resolution was 75, and --disable-dynamic-lineart was no.
Setting options '--disable-dynamic-lineart=yes --resolution 300' for '--mode Lineart' solved the problem.

2017. június 16.

Finding the rightful heir to HP Compaq TC-4400 tablet PC

Finding an affordable business class tablet PC with pen support is not easy nowadays.

Here are some sites that might help with finding something with pen support:

2017. június 11.

Migrating from Ubuntu 12.04 LTS to 16.04 LTS on HP Compaq TC4400 Tablet PC

Setting up Xenial is very similar to setting up Trusty.

First of all, I install synaptic and gdebi, because I don't like the Ubuntu Store thingy:
  • sudo apt-get install synaptic gdebi
Then get back the Gnome Classic look:
  • sudo apt-get install gnome-session-flashback
  • log out to change the window manager by clicking on the icon next to your user name then login again.
Then set up gnome-session-flashback with Compiz
  • Add something to the panel: Alt+Super + Right click
  • Set number of workspaces
    • sudo apt-get install compizconfig-settings-manager
    • in Compiz Config Settings Manager navigate to General / General Options / Desktop Size set the size you want.
  • Change date-time format on panel
    • sudo apt-get install dconf-editor
    • in Dconf Editor navigate to com > canonical > indicator > datetime
      • Set "time-format" to "custom"
      • Set "custom-time-format" to the format you want, i.e. %Y-%m-%d %H:%M:%S
      • Make sure that "show-clock" is check-marked. 
  • Change the Indicator App on the panel to show less
    • Gnome Session Flashback installs indicator-applet-complete, but there are more then one indicator applet that can be downloaded with synaptic. The difference between them is this:
      • indicator-applet-complete is: messaging applications, power settings, bluetooth settings, network settings, sound settings, date and time settings, user accounts, session management
      • indicator-applet is: messaging applications, power settings, bluetooth settings, network settings, sound settings
      • indicator-applet-session is: user accounts, session management
      • indicator-applet-appmenu is: your active application's menu header
    • Other settings can be changed in the Dconf Editor under com > canonical > indicator. (i.e. turn off the language icon)
  • Turn off effects:
    • in Compiz Config Settings Manager navigate to Effects and turn off Animations
  • Set Nautilus (Files) default view to List
  • Make .sh files run on double click

Creating searchable PDFs on Ubuntu 3rd try

Following up on the second try:

My requirements:

  • image layer over text layer
  • good character encoding for Hungarian ű and ő chars
  • good placement of words and lines
  • fair enough good recognition
  • handling more column layout


Set up Tesseract:
  • sudo apt-get install tesseract-ocr
  • from https://github.com/tesseract-ocr/tessdata download the language data you need and put it in tessdata directory (/usr/share/tesseract-ocr/tessdata). E.g. for Hungarian:
    cd /usr/share/tesseract-ocr/tessdata
    sudo wget https://github.com/tesseract-ocr/tessdata/raw/master/hun.traineddata
  • add environmental variable TESSDATA_PREFIX to the directory containing the tessdata directory if you get the error that the language data cannot be found.

Tesseract supported input image formats:
...are the ones supported by Leptonica:

Tesseract searchable pdf output
Example usage with specified language (-l):
tesseract  input.png outbase -l hun pdf

  • image layer over text layer - YES
  • good character encoding for Hungarian ű and ő chars - YES
  • good placement of words and lines - YES 
  • fair enough good recognition - YES: it depends a lot on input quality.
  • handling more column layout - SO-SO: sometimes works (i.e. half page is OK, other half is single column)

This is good enough for me now, so I'm not investigating further.

Set nautilus default view to list

I have no idea how to open this 'Edit > Preferences' window in the gnome flashback, but the dconf editor version worked for me:

  1. Open dconf Editor
  2. Navigate to org.gnome.nautilus.preferences
    1. Set the 'default-folder-viewer' to 'list_view'
  3. Optionally: Navigate to org.gnome.nautilus.list-view
    1. Set the 'default-zoom-level' to 'smaller'
    2. Set the 'use-tree-view' to true