ImageMagick display

ImageMagick display

The display program of ImageMagick is useful when you are at the shell and need to quickly view one or a few images. It can also be used to apply many of the image processing operations available in ImageMagick on an image and view it. This viewer is extremely light and great for checking some images quickly on a remote computer over SSH.

  • If you do not have ImageMagick, installing it is easy:
$ sudo apt install imagemagick
  • To view a specific image:
$ display foo.jpg
  • To view all the JPEG files in current directory:
$ display *.jpg
  • To display all image files in current directory:
$ display *
  • If you know that you will not be changing the images, but just viewing them, then open them in immutable mode:
$ display -immutable *.jpg
  • Press F1 to view help about the mouse operations and keyboard operations available in this program.

  • Some of the keyboard shortcuts I frequently use:

Space: Next image
Backspace: Previous image
Esc: Quit
/: Rotate by 90 degrees
<: Zoom out
>: Zoom in

Tried with: ImageMagick 6.8.9.9 and Ubuntu 16.04

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Review of Dell S2415H

It has been 6 months since I started using the Dell S2415H display at both home and work. The S in Dell displays is the budget series compared to the premium U series. I have been very happy with what I got for the price and I can no longer imagine working at my tiny notebook display anymore!

  • Size: As you might guess from the model number, this is a 24-inch display. It looks smaller than one though because it has almost zero bezel. Once you use such an edge-to-edge display, you cannot go back to thick bezels. An added advantage of zero bezel is it is great for dual and multi-display setups cause it gives you the feel of a huge display.

  • Resolution: 1920×1080. Not as high as I would like, but fine for my coding and browsing.

  • Inputs: HDMI and VGA. This is where Dell really cut down on the features. No DVI or Displayport! I do not play games and my notebook and graphic cards have HDMI and VGA outputs, so I am fine.

  • Color: This is where IPS really shines through. Everything looks rich and vivid. The color gamut is great and the brightness even at the lowest brightness setting is way high. I actually wish Dell had provided lower brightness levels cause using this display in dark room at night is hard on the eyes.

  • Glossy: This is one of my biggest problems with this display. It is very very glossy. It looks great to visitors and in photos. But a pain while working, especially if you are working with black terminals or themes. Note that the U series display are sensibly matte and do not have this problem.

  • Stand: The stand is dead simple and the only rotational alignment that can be done is along the horizontal axis. Not a problem for me cause I just place it on thick books to increase its height.

  • Price: It is very affordable. I doubt you can get a better deal on an IPS display with such a color gamut, good color calibration and such brightness levels. If you can afford it, you should definitely go for the U series displays, cause they are worth the extra cash.

  • Linux: I use the display with Kubuntu and it was detected correctly in its settings and works fine.

In conclusion, this is a good display from Dell and I am loving it. If you can afford it, I highly recommend the U series, which also I use regularly.

How to update environment variable of existing Tmux session

Problem

I use Byobu (which is a wrapper on Tmux) to maintain shell sessions on the many servers I login to. I connect, disconnect and reconnect to the same Tmux sessions on these servers. When I reconnect back to an existing Tmux session, a new value is assigned to the DISPLAY environment variable. If I create a new Tmux session, by opening a new split or tab, then Tmux sets the new DISPLAY value correctly for that session. However, existing Tmux sessions have their old DISPLAY value which gives the familiar cannot open display error. I can find out the new DISPLAY value and set it manually in the existing session, but that is cumbersome.

Solution

I found a simple solution to this problem. Whenever I SSH to a server, I save the new DISPLAY assigned to this server in a .display.txt file in the home directory. For example, this can be done in .bashrc:

echo $DISPLAY > ~/.display.txt

To pick up the new DISPLAY value from this file in existing sessions, create a shell alias or function that you can call when you realize that the environment variable is wrong.

For example, for Fish shell, I added a ~/.config/fish/functions/set_display.fish file with these lines:

function set_display
    set --export DISPLAY (cat ~/.display.txt)
end

When I need to update DISPLAY, I just call set_display at the shell! 🙂

Tried with: Byobu 5.74, Tmux 1.8 and Fish 2.2.0

Display resolution not shown in Ubuntu

Problem

I uninstalled my NVIDIA drivers using this command:

$ sudo apt-get purge "nvidia*"

I rebooted my computer and logged into Ubuntu. I was greeted by a desktop of resolution 1280x768. This was far lesser than the native resolution of this display, which is 1920x1080!

When I opened System Settings -> Display, only the above low resolution was available in the dropdown!

Solution

Online solutions point to using xrandr to pick the display resolution and make it permanent. Since my system was due for a new LTS Enablement Stack, I went ahead and updated the Linux kernel and X server as described here.

After rebooting from this update, my desktop was back to its full native resolution! 😄

Tried with: Ubuntu 14.04

How to view or change dim time of display in Ubuntu

Ubuntu dims the display when the computer is idle for a certain period.

The current value of this time in seconds can be seen using:

$ gsettings get org.gnome.settings-daemon.plugins.power idle-dim-time

To change this dim time value, for example to 300 seconds:

$ gsettings set org.gnome.settings-daemon.plugins.power idle-dim-time 300

Tried with: Ubuntu 12.04 LTS