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Basic photo editing with Darktable

by Martin de Boer

When I was starting in the world of amateur digital photography, I learned about 2 software programs that everybody was using: Adobe Photoshop and Adobe Lightroom. In the Free and Open Source world, there are 2 amazing alternatives: GIMP and Darktable. GIMP is aimed at destructive (the image is changed when saved) photo editing. It can be used to change photos in many ways, including cutting things out of the picture or pasting things into the picture. Darktable is aimed at non-destructive photo editing. I like to compare it to developing a photo. The negative is kept, and the photo (the positive) is developed from the negative. For many people, getting started can be daunting. Therefore I like to present the absolute basics of photo editing with Darktable.


First open Darktable. When the program is opened, you need to load a photo collection. You can do this for many photos at once by clicking on ‘folder’ in the left sidebar in the ‘import’ section.

Select the folder in which you have stored the RAW files of your digital camera. Click on open.

Note: If you only take JPG pictures with your digital camera, Darktable is not for you! You should look into GIMP.

Now your photos will load in the Lighttable section of Darktable. In the top right of the program, you can see (highlighted) in which section of Darktable you are currently working. To start editing a photo, double click on the image.

Now you are automatically moved into the darkroom section of Darktable. Underneath the sections you see a Histogram (the colored chart) and below that a row of buttons. These buttons are the groups in which the functions of Darktable are grouped. Now click on the ‘basic group’ button. Then click on ‘white balance’.

The easiest way to get the white balance right is to find a white spot on your photo and select this. To be able to do this, you first need to go into the white balance presents and change this from ‘camera’ to ‘spot’.

Now you can zoom into the photo by using the mouse wheel (if you have one) or by using the navigation functions (located in the top of the left sidebar). Then select the part of the picture that represents pure white and Darktable will automatically determine the white balance. When I am not 100% happy with the result, I simply try again on another spot.

You can also use one of the presets that are available by default such as: camera, daylight, shade, cloudy or flash. Or you can manually drag the temperature left-right to select the white balance that you prefer.

After having selected the right white balance, it is time to get the light/dark area’s of your photo right. Go into the tone group. Now select levels.

What you want to do, is look at the histogram and see where it drops off. Most histograms look like a mountain range with an upward slope on the left, a middle part that’s like a mountain range and a downward slope on the right. If you don’t see a slope on the left, that means that your dark areas are fine. If you don’t see a slope on the right, that means that your light area’s are fine. What you want to do, is to drag the line on the left or on the right towards the middle, so that the slopes are shorter or even gone. Try to experiment with this!

The last group in this tutorial is the correction group. Select the lens correction.

Now you want to enable the lens correction with the ‘on’ button of the module. In most cases, the camera and lens are already selected correctly by Darktable. Otherwise adjust the camera model and lens to the ones that you have used.

The only thing remaining is to export the photo(s) into the JPG format. Click on lighttable, to change the Darktable mode. Then in the right sidebar go to the ‘export selected’ part and click on the folder icon to select the folder where you want the pictures to be saved. Now select all the images that you want to export (in the middle section) and then click on the export button.


Using Darktable is not as difficult as it might seem. You just need to know your way around. There are a lot more functions available. But the ones in this tutorial are enough in 95% of the time. In future blog posts, I will explore some of the more advanced features.

Published on: 15 October 2018

How to create great panorama photos with Hugin

by Martin de Boer

If you search online for “Best Panorama Stitching software 2018”, chances are very high that you find an article that mentions Hugin (1, 2, 3). The reason is that this is one of the best programs to stitch photos for Linux, MacOS and Windows. And it is free and open source! The criticism is that its aimed at professional users and that it can be a bit overwhelming for new users. This article will provide you with a rundown on how to use Hugin. I have used openSUSE Leap 15 as my operating system, but this tutorial will work across distributions and operating systems.


  1. Start the Hugin Panorama Creator. The Assistant tab is the first thing that you will see. Click on Load images.

  2. Select the images that you want to use to create a panorama.

  3. Next, click the Align button to auto-align the pictures.


  4. Now go to the Projection tab. I recommend that you try different ways of projection. I mostly use the options Rectilinear, Cylindrical or Architectural. This really can’t go wrong, because you can always go back to the default, which is Rectilinear.

  5. Then go to the Move/Drag tab. I would recommend to only use this feature when the picture has an incorrect angle or is really off-center. It never hurts to try, but be aware that the buttons (Center / Fit / Straigthen) might deform the picture in a way that you don’t like. In that case, it is better to start all over again (Click on File –> New). There is no Undo button! In the example below, I use this feature to correct the angle of the panorama.

  6. Now it is time to perfect your panorama. Go to the Crop tab. I prefer to use the sliders inside the picture, to determine the correct borders (up, down, left and right). It gives you a lot of control over the final picture. You can also use the Autocrop button, but where is the fun in that?

  7. After all necessary adjustments are made, go back to the Assistant tab. Now click on the Create panorama button.

  8. Now you will be asked how to adjust for the differences in exposure. I will always start with either the first option (Exposure corrected, low dynamic range) or the second option (Exposure fused from stacks). This depends on my visual inspection of the photo’s. If I see a lot of differences (some are very bright, some are darker) I tend to choose the second option. If the differences are not so pronounced, I usually stick with the first option.

  9. You will be asked to save your project and save the picture. The project will always be saved as a .pto file. The picture can be saved in different formats. But I leave it on Tiff. After the panorama is created and if I am happy with the results, I use GIMP to convert the panorama to the Jpeg format.

  10. Hugin will now create the panorama. This can take a while, so you need to wait for a minute or maybe two. You can view the end result here in a higher resolution.


Manual alignment

Hugin has an advanced feature for manually aligning the pictures. Although this feature gives you a lot of control over the stitching of your photo’s, most of the time you don’t need to bother with it. In 98% of the times, Hugin does it automatically and does it well. But there are still situations where Hugin is not able to auto-align. And in these cases, you need to use the Panorama editor (View –> Panorama editor). In the Panorama editor you can manually determine the control points (the points that are the same in both pictures) for photo’s that need to be stitched side by side. It is not so hard, once you get the hang of it. You select the pictures that need to be next to each other with the drop down buttons. Then you click on a point that is very distinctive on both pictures. And then click on the Add button. Once you have ~10 control points between the 2 pictures, Hugin should be able to stitch them perfectly.


Hugin might seem a bit overwhelming for new users at first. But once you get the hang of it, it is an easy program to use. It allows you to capture that incredibly beautiful landscape in widescreen.

Published on: 1 August 2018

Installing Rapid Photo Downloader 0.9.9 on openSUSE Leap 15

by Martin de Boer

Have you noticed? After installing Rapid Photo Downloader from the openSUSE repositories, it doesn’t launch. As indicated in an earlier blog post, this program is really great to download your photo’s into the right folders in one go. Version 0.9.9 is a big overhaul for this application. If you want to use it right now, you need to install it using these instructions.


The first thing to do is to install, then remove Rapid Photo Downloader using YaST. Why install a program and remove it the next moment? Because this ensures that you have 99% of the package dependencies installed, that are needed to run the application. There are 2 more software packages that you need to install:

  • python3-wheel
  • intltool

The second step is to go to the Rapid Photo Downloader website and download the install script. If you haven’t changed the Firefox download settings, this should end up in your Downloads folder.

Open your favorite terminal application (Konsole) and run the command to go to your Downloads folder. Replace “name” with your username:

cd /home/name/Downloads

After that, run the command:

python3 install.py

In the end, you will be asked for your root password. Enter it and the installation will finish.

To be able to launch the application from the application launcher, you need to adjust the launch command. Go to the application launcher and right-click on the openSUSE logo (context menu) and choose “Edit applications…”

Go to the Graphics section, click on Rapid Photo Downloader and change the command. Replace “name” with your username:


Click on the Save button and close the KDE Menu Editor.

For everyone who hasn’t installed the openSUSE drivers for exFAT yet, this might be needed to read your SD card. So if you notice that Dolphin cannot mount your SD card, try installing:

  • exfat-utils


The look and feel of Rapid Photo Downloader has changed dramatically compared to the previous (0.4.3) version.

This means that you need to configure the application to your liking. This includes:

  • Choosing the main folder for your photo’s and configuring the sub-folder creation logic
  • Configuring the photo renaming logic
  • Choosing the main folder for your videos and configuring the sub-folder creation logic
  • Configuring the video renaming logic

In my previous blog post, I have showed the way that I have setup my folder creation and renaming logic. Because of the large changes to the application, I will display my configuration for Rapid Photo Downloader version 0.9.9 here as well.

The only thing remaining is to use the application to download your photo’s. Select the photos that you want to download and click the checkbox in the lower left corner of the bottom picture to select them. Finally click on the large blue button “Download ## Photos” on the top right of the application. Now Rapid Photo Downloader will auto-magically download all photos to your openSUSE computer… exactly how you want it.

Published on: 19 July 2018

Discovering the Gwenview photo viewer

The Gwenview photo viewer is a great application and one of the reasons why I never looked back when I switched from Windows (Vista) to openSUSE (11.1). The application is installed by default when you install openSUSE with the KDE plasma desktop environment. But even if you have the GNOME desktop environment installed, I would recommend that you to install Gwenview. In my opinion, it is superior to the GNOME image viewer application.

Default applications often get overlooked. We just expect them to be there. But there are big differences when it comes to default applications. Take for instance the GNOME image viewer or Windows Photo Viewer. You can do a couple of basic things like zoom in, zoom out and move from photo to photo. You can put it in full screen mode and go back. And of course you can open, save, print and close photos. But that is basically it. Gwenview does a lot more.

So lets get to it. There are basically 2 ways to open Gwenview. The first way is to (double) click a photo in the Dolphin file manager (another great default application). The second way is to open Gwenview via the kickoff menu, by typing in the name in the search box or by looking at the Graphics section of the menu.

Gwenview contains a couple of elements. On the right side is a navigator bar that allows you to navigate to any folder on you computer. On the right are recent folders and recent files (photos) that you have accessed. So lets access one of these folders.

This will move you to the Browse mode of Gwenview. I have highlighted one of the cool features of Gwenview. The ability to easily move between photo folders. It is really great to be able to move between folders as quickly as this. No need to close the application.

Next is the View mode. You enter this mode by clicking on a photo. The highlighted section (below) in the top toolbar show the ability to move to the previous / next photo, to rotate the photo (by 90 degrees) counterclockwise / clockwise. The highlighted section in the bottom toolbar provides you with the ability to make the photo fit to the current window or zoom in to 100%. You can also use the slider to determine a custom zoom percentage.

Whenever you use the zoom feature, you have the ability to move around the picture using the navigator that will show just above the zoom controls.

Third is the Full Screen mode. This will not only show your pictures in full screen, but also gives you the ability to play your pictures as a Slideshow. When you move the mouse cursor to the top of the screen, a menu (black bar) will show various controls. The controls on the left side allow you to start the slideshow or to quickly scroll to a certain photo.

The controls on the right side allow you to adjust the slideshow settings.

A very neat feature of Gwenview is the sidebar. You can get access to this by either clicking on the sidebar button (left of the Add filter button), by pressing F4 or by going to View >> Sidebar. The sidebar allows you to navigate the folder structure of your computer.

The second tab of the sidebar allows you to see information on the selected picture. For this, you need to click on a photo. To see a lot more information, click on the More button that is highlighted in the picture below.

You can now scroll through a very long list of properties that your camera has captured while taking the photo.

Gwenview also allows you to do some basic photo editing. This is where the 3rd tab in the sidebar comes into play. Gwenview allows basic operations, such as mirroring, flipping, resizing and cropping the picture. A neat feature is the ability to remove red eyes in photos. You can also use Gwenview for some basic file operations, such as renaming, trashing, deleting, copying or moving a photo.

You think I have covered all the cool functionality of this application by now? No sir! (or madam!) Gwenview has multiple plugins. The first plugin I like to discuss is the print assistant. You can access this by going to Plugins >> Images >> Print assistant… The print assistant allows you to create (PDF) pages with multiple photos in various layouts.

Another cool feature is the ability to e-mail resized photos. This is handy when you want to share your holiday photos, but don’t want to send all these photos in full resolution (an 18 megapixel photo is about 14 MB in file size in Jpg). You simply select the e-mail program that you like to use (I selected Thunderbird) and then click on the option to Adjust image properties.

And one of the top features is the ability to import from / export to various web based photo applications. You can access this via the plugins menu. Or just click the Share button for the export options.

This covers all cool features of Gwenview. This application might be installed by default, but it is certainly not a basic photo viewer. It is a great application in its own right and a tool that I like to use time and time again.

Published on: 9 May 2018

A quicker way to download photos on openSUSE

A very common way to download your photos on your openSUSE desktop is to use the file browser. This might be Dolphin (KDE) or Files/Nautilus (Gnome). First thing you do is create the new folders that you need for your photos. You plug-in the SD card or connect your camera via USB cable. And then you drag the photo files to the location(s) of your choosing.

But there is a smarter and quicker way and its called Rapid Photo Downloader. And once you try this program, you never want to go back. The easiest way to get this program is just search for “rapid-photo-downloader” in YAST Software Management, select “Install” and then “Accept”. After the installation you should be able to find the program under the “Graphics” section of your Application Launcher menu.

One time configuration

To start the configuration, go to the Preferences of this application. This is where you perform the initial (one time) setup of how you want to import your photos and videos.

Start with setting up the folder where you want all your photos to go. Click on the drop-down for the “Download folder” and select “Other…”.

Then select the folder that you want to use for your photos. I like to know what camera I used for taking the photos. But you might be content with just the subfolder Photos.


The magic of Rapid Photo Downloader is that you can specify how the application will automatically create the future folder structure for your photos. I like to use folders per month. For example: “2018 03”, “2018 04”, “2018 05”, etc. You can specify this by using the settings (marked in red) in the screenshot below. As you can see from the screenshot, I also create a sub folder named RAW.

The second part of the magic of Rapid Photo Downloader is that you can specify how to automatically rename your photos. I have chosen a very simple setup, where I concatenate the image date and the original name and extension with an underscore in between.

Now you are done with the setup for the photos. Continue with the setup of the videos. In the screenshots below you can see the setup that I use.

Now close the preferences window.

Downloading photos

Downloading your photos is very easy. The first thing you have to make sure is that you have plugged-in the SD card or have connected your camera via USB cable. The second thing you need to do is to mount the external photo medium by simply opening the folder once in your file manager of choice. Then startup Rapid Photo Downloader. The program will automatically detect the photo medium and load all photos on the card. Most likely you are only interested in the latest photos that you haven’t yet downloaded. So click “Uncheck All” to clear the current selection. Then select the first photo that you like to download.

Now scroll down to the last photo, hold down the “Shift” key on your keyboard and select the last photo you want to download. If you are fine with the selection, click on “Download”.

Now Rapid Photo Downloader will auto-magically download all photos to your openSUSE desktop… exactly how you want it.

Published on: 3 May 2018