Qt5-based image viewer PhotoQt
Doubtful Candidate

© Lead Image © Maksim Shebeko, 123RF.com
The lean PhotoQt tries to join the ranks of modern image viewers, but it's still not very stable.
Various image viewers are available under Linux, but if you want to view RAW images, the choice becomes considerably restricted. You are left with veterans like Geeqie [1] and Shotwell [2]. Both offer far more than merely displaying the many different formats – each in their own way.
PhotoQt [3] – a relatively young project – is now trying to gatecrash the veteran party. Its first release, version number 1.2, dates back to January 2015. This article is based on the current 1.5.1 version. Many repositories already contain the software, and the installation does not typically cause any problems. On the homepage, you will find instructions for many distributions. On Ubuntu version 15.04, you can do:
$ sudo apt-add-repository ppa:lumas/photoqt $ sudo apt update $ sudo apt install photoqt
to set up PhotoQt from the PPA for the project.
Requirements
If you use an image viewer for a larger number of images, some features are useful or even essential. These in particular include different ways to browse or sort the images. The program needs to be able to evaluate the metadata contained in the images, that is, the Exif tags. Additionally, it should ideally offer an option for including reviews or keywords in the search.
In the case of RAW images, access to embedded thumbnails is a big help, and it accelerates the display in many cases. The RAW formats also contain metadata. It is particularly useful if you also have the option of using the raw data for the preview.
As the PhotoQt developer Lukas Spies states on the homepage, his interests are strongly focused on using the graphics processing unit (GPU). Today, this is often the most powerful processing unit in a computer.
Features
PhotoQt relies on modern technology with a combination of Qt5/QML. The program supports many formats through the use of GraphicsMagick and LibRaw. However it is pretty lame at times, such as when loading the thumbnail. And, PhotoQt only supports images in 32-bit color depth.
The program has functions for rotating, mirroring, and enlarging the pictures. You can directly rename, copy, move, and delete the image files. For many actions, keyboard shortcuts are available (Table 1); you can modify these if necessary and add your own.
Table 1
Shortcuts
Shortcut | Function |
---|---|
O |
Open image/directory |
Home/End |
Show first/last image |
Left arrow |
Show previous image |
Right arrow |
Show next image |
+/- |
Scale display |
0 |
Set default resolution |
Ctrl+F |
Filter |
R/L |
Rotate left/right |
Ctrl+H |
Flip image horizontally |
Ctrl+V |
Flip image vertically |
F2 |
Rename image file |
Del |
Delete image file |
Ctrl+C |
Copy image file |
Ctrl+M |
Move image file |
E |
Display settings |
Ctrl+E |
Show Exif info |
M |
Start slideshow; show Exif info |
Shift+M |
Start slideshow in the current directory |
The wallpaper function did not work consistently in the test. A slideshow displays a series of images without the need to switch manually. If necessary, the program can add the Exif information for the displayed images.
PhotoQt allows many customizations, more than many other viewers. It caches thumbnails of the loaded images. If you need quick access to the program, you can drop it into the system tray. Some rudimentary options let you control the behavior of the software when launched.
Hands On
By default, PhotoQt launches in full-screen mode and loads the images from the current directory. Alternatively, there is a mode with window decorations, and a several options that let you set the behavior of the program. Thanks to the semitransparent interface, you still see the desktop despite displaying images. This is modern but has no practical value (Figure 1). At the center, animated bars visualize loading the images.

By default, there only a few ways to toggle between images. For example, it is not possible to toggle between images with the mouse wheel. However, you can customize the controls to suit your needs. To do so, use the menu that opens up when you move the mouse pointer to the right edge of the screen (Figure 2). Below Settings is a comprehensive dialog with several tabs with which you can configure nearly all the aspects of the program.

Below Shortcuts, you can map keys and mouse events to functions (Figure 3). To change the images with the mouse wheel, first select the Next image function and then perform the desired action. Then, repeat the whole thing for the Previous image function. Then, select Save changes and close to quit the dialog.

If you were looking for a context menu that is quickly accessible with special functions in PhotoQt, you can stop now; this tends to make working with the program unnecessarily complicated. The online guide provides information about the most important settings [4] among other things. However, the document completely ignores the filters.
PhotoQt can display the metadata for images (Figure 4). Essentially the software is limited to the Exif information. The corresponding function still showed some weaknesses with most of the (raw) formats, delivering only a File format is not supported message; however, if necessary, you can display a histogram.

PhotoQt transfers the images to Gimp for processing – this is probably not the right way to handle RAW images. A RAW converter would be the better choice. However, Gimp does let you automatically call a converter (now including Darktable).
The Viewer uses a bar at the bottom of the window for the thumbnails (Figure 5). However, it only appears when you move the mouse pointer to the bottom. You can use the mouse to browse the images in the bar and click to select the one you want.

However, the main window does not always show the image under the mouse pointer in the preview bar, but the one that is highlighted in the bar – this is somewhat confusing at first. Caching also apparently doesn't work when displaying RAW images; the result being that image changes can take a very long time.
Buy this article as PDF
(incl. VAT)
Buy Linux Magazine
Subscribe to our Linux Newsletters
Find Linux and Open Source Jobs
Subscribe to our ADMIN Newsletters
Support Our Work
Linux Magazine content is made possible with support from readers like you. Please consider contributing when you've found an article to be beneficial.
News
-
Red Hat Migrates RHEL from Xorg to Wayland
If you've been wondering when Xorg will finally be a thing of the past, wonder no more, as Red Hat has made it clear.
-
PipeWire 1.0 Officially Released
PipeWire was created to take the place of the oft-troubled PulseAudio and has finally reached the 1.0 status as a major update with plenty of improvements and the usual bug fixes.
-
Rocky Linux 9.3 Available for Download
The latest version of the RHEL alternative is now available and brings back cloud and container images for ppc64le along with plenty of new features and fixes.
-
Ubuntu Budgie Shifts How to Tackle Wayland
Ubuntu Budgie has yet to make the switch to Wayland but with a change in approaches, they're finally on track to making it happen.
-
TUXEDO's New Ultraportable Linux Workstation Released
The TUXEDO Pulse 14 blends portability with power, thanks to the AMD Ryzen 7 7840HS CPU.
-
AlmaLinux Will No Longer Be "Just Another RHEL Clone"
With the release of AlmaLinux 9.3, the distribution will be built entirely from upstream sources.
-
elementary OS 8 Has a Big Surprise in Store
When elementary OS 8 finally arrives, it will not only be based on Ubuntu 24.04 but it will also default to Wayland for better performance and security.
-
OpenELA Releases Enterprise Linux Source Code
With Red Hat restricting the source for RHEL, it was only a matter of time before those who depended on that source struck out on their own.
-
StripedFly Malware Hiding in Plain Sight as a Cryptocurrency Miner
A rather deceptive piece of malware has infected 1 million Windows and Linux hosts since 2017.
-
Experimental Wayland Support Planned for Linux Mint 21.3
As with most Linux distributions, the migration to Wayland is in full force. While some distributions have already made the move, Linux Mint has been a bit slower to do so.