Photography: Digikam

I’m a prolific digital photographer. Since buying my first decent camera last year I’ve come to think of digital photography as one of my favourite hobbies. I have a collection of some 5000 images - many of them requiring some enhancement - and I’ve found the tools on Linux for touching up and managing photographs to be second to none. This month I’ll be showing you what I’ve learned about how to use the basic editing and photo management functions in Digikam (http://www.digikam.org/Digikam-SPIP/), as reviewed in the August issue of TUX.

Red Eye Reduction:

While most cameras now have a mode to minimise red eye in flash photography, it still happens far too often. Digikam comes with a simple to use red eye correction tool. Open your picture in the digikam editor and zoom right in on the eyes. I find it easier to be precise the bigger the area is I have to select. Once you’ve zoomed right in, use the mouse to draw a selection around the iris of the eye . The unselected area of the photograph will fade out, helping you to focus on the area you’re working on. Now select ‘Red Eye Reduction’ from the ‘Fix’ menu.


Red eye correction tool

If you’ve managed to select the eye quite precisely, select the radio button next to ‘Agressive’. Click ok, and repeat the steps on the other eye. You might find it helps to run the filter two or even three times over each selection if the red eye effect is particularly bad as in the example photo. The filter isn’t perfect, but as we zoom back out again you can see a marked improvement over the original image.


After using the red eye correction tool

Crop & Resize.

If you’re planning to send your images via email or post them on the web then you probably want to resize them to a more web-friendly size. You also probably would like to crop the picture to adjust the positioning of the subject, or remove unwanted background details. I like to use the aspect ratio crop tool for this, which allows me to make sure the cropped image is in the same width to height ratio as the original. This lets me later resize all of my photographs to a uniform size for posting on the web.


The aspect ratio crop tool

Open the image you’d like to crop in the Digikam editor, and select ‘Aspect Ratio Crop’ from the ‘Transform menu’. Select the aspect ratio you want from the ‘Aspect Ratio’ drop down box. The example I’m going to use here is 4:3, as I’ll later resize the image to 800×600 for putting on the web. In the image window, use the mouse to drag the frame around, centering it over the part of the image you’d like to crop to. You can enlarge or shrink the frame by dragging it’s corners. Click ‘Ok’ when you’re happy with your result. You’ll see your newly modified image in the viewing window. Now you can resize it to a more web-friendly size by selecting ‘Resize’ from the ‘Transform’ menu. Type your desired width into the width box, and press the tab key to have the height box automatically filled in. Click Ok when you’re finished. Digikam scales images to fit into the image window by default, so to see the size of your new image you may have to click the ‘Zoom Autofit’ toolbar button to temporarily turn this option off. You can also toggle this option with the keyboard using the ‘a’ key.


The cropped & centered image

Brightness & Contrast.

This photograph was taken standing at the foot of a runway, snapping aircraft as they flew overhead to land. Since the plane was being shot against a very bright sky the camera took a very short exposure and the plane is a little dark. To fix this, we use Digikam’s ‘Brightness/Contrast/Gamma’ tool found in the ‘Fix -> Colors menu’. Use the sliders to adjust the brightness, contrast and gamma to your liking. One tip is that when you increase brightness you should also increase contrast and perhaps decrease gamma slightly to keep natural looking colors.


The brightness/contrast/gamma tool

Noise

One problem with increasing the brightness of a dark picture is that it tends to give more noise. To reduce the speckled appearance you can use the ‘Noise Reduction’ tool from the ‘Fix’ menu. This softens and smooths the appearance of the picture by applying a slight blur effect, so use it sparingly. Adjust the sliders until you get the effect you want based on the preview displayed.


Despeckling an image using the Noise Reduction tool

Color Correction


The color balance correction tool

This photograph was taken on a bright sunny day - having left the wrong preset selected on my camera! The preset for indoor photography puts a slightly bluish cast to give more natural looking colours under yellow light, and gives rather unfortunate effects outdoors if you forget to turn it off. You can fix the color balance of a photograph like this using the ‘Color Balance’ tool, found in the ‘Fix -> Colors’ menu. Since this particular image is a little too blue, we want to give it more warmth. Adjusting the sliders to give us more yellow, red and a little green lends this photograph a more natural hue.


The original and the corrected image

Managing Photographs

Digikam makes an excellent photo library. As well as the traditional concept of albums, it introduces tags for sorting of photographs by category. Photographs can have multiple tags, allowing you to search for related groups of photographs easily irrespective of what album they are in or what date they were taken. To create a new Album, right click on ‘My Albums’ in the sidebar of the Album view and select ‘New Album’. Give your album a title and a comment, and optionally select a category for it. The simplest way to import photographs into your albums is to drag and drop them from konqueror. Highlight the group of photograps you’d like in your album and drag them with the mouse into the Digikam album view window. Digikam will copy the photographs into the album. To set captions and comments for individual photos, right click on the thumbnail of the photograph and select ‘Edit Comments and Tags’. You can add new tags from this window by right clicking in the Tags pane, or from the ‘Tag’ menu. The Tag tab on the sidebar takes you to a view that shows you your images grouped by tag and what album they come from.


The tag management view

Presentation

Digikam has a great tool to export your images to a HTML gallery you can post on the web. Any comments you’ve added to your images will be printed below the photograph in the gallery. Select ‘HTML Export’ from the ‘Album -> Export’ menu and select the albums you’d like to export to the web. Click on ‘Look’ on the iconbar to modify the title of your Album. Once you’ve finished customizing the options, Click ‘Ok’. By default the gallery is created in your home directory, and is opened in Konqueror for you to preview once you’re done. Now you can upload this folder to your web space. If you don’t like the default folder name, you can rename it to anything you like.

Gphoto2 Integration

Gphoto2 is a a digital camera application that acts as a driver to communicate with your camera. Digikam can integrate with Gphoto2 to make downloading pictures from your digital camera a breeze. This page (http://digikam.free.fr/hotplug/howto.html) shows you how to set up hotplug, Digikam and Gphoto2 to automatically launch digikam and connect to your camera when you plug it into your computer. This is a wonderful feature advanced users might like to set up for not-so advanced users so even Dad can feel that using Linux with his camera is easy.


Digikam connecting to a digital camera through

If you’re a Gnome user, you may like to have a look at my articles on Gthumb and F-spot