Digital photography requires a solid workflow, allowing for professional preparing of digital photo files for the web and print. For the Digital Photography Workflow series, we consulted with a number of experienced professional photographers who are also stellar photo.net members and frequent contributors to the Photo.net Digital Darkroom forum, to walk us through their specific photography techniques and tips on post-processing images.
In this article, Jean-Sébastien offers advice on how to stitch together panoramas using Autopano Pro. The article is enhanced with illustrative figures and screen shots, and includes example images from Jean’s portfolio. Whether you are just entering the world of digital photography and need some tips and advice on how best to post-process your images, or are a seasoned pro, the insights shared here should be helpful with your own digital post-processing techniques.
What you can do with Autopano Pro
Autopano Pro has been created to automatically process images and find panoramas from your local files, even if you had no prior knowledge and that your camera was set to fully-automatic operation. However, I would advise you to at least set your white balance manually before shooting. When the contrast is high, you might need to shoot several photos, and adjust exposure to get details in the shadows and highlights. Autopano will then be able to adjust luminosity and make the best of your photos. Here is a set of photos that I have shot [31 and 45].
Using Autopano to Create Panoramas
Autopano reads JPEG, TIFF, PNG, BMP, as well RAW from many cameras. Once you launch it [Screenshot 1] and open a folder , it will automatically detect the panoramas from the images you’ve loaded, trying to stitch them together. Options can be set to help this process as you can see from the dialog box.
Once images are loaded , pressing the Play button will launch the automatic detection of panoramas . This takes some time as lens distortion and various adjustments are also addressed during this process . I would advice to only run it on selected files, rather than the whole directory of your holidays photographs.
The result is a list of available panoramas from you to choose from [8, 9].
You can use the Edit button to adjust a panorama or simply render it by clicking on Process .
The panorama editor provides several options .
We are going to have a more detailed look at them. First thing you notice is that the image is tilted. Use to fix it .
Various tone-mapping options are possible. For a quick start, you can go to Tone Mapping RH2 . The dialog offers a way to adjust luminosity through the Key value as you can see on the two examples [19, 20]. You can play with that until you are satisfied or use the Levels as described below. The Tone Mapping RH2 is actually more useful for HDR, as we will see later on.
Various projections are also possible. Architecture fans will love the Planar projection whereas regular panorama users will probably stick to the Spherical. The Planar projection will tend to create straight lines whereas Spherical better recreates what you have seen.
The Levels are similar to those in Photoshop. Playing with the Gamma point makes the image brighter or darker, whereas the black and white points of the histogram help you make sure to achieve the tonal range that you are looking for. In the example, I could for instance raise the black point a little bit to the right until it touches the histogram.
Once you’re done, click on Process and you’ll get an option dialog . It is possible to save your file in Photoshop format, keeping the layers intact for further adjustments. I found it quite useful to set up my DPI to 300, and then move the scale factor until I’m pleased with the size of the generated image.
When you open your image in Photoshop , you will notice that all layers are there. A close inspection shows that the blending isn’t perfect on one layer. To address this, I simply add a mask to the layer and then paint in black over it . The result is much smoother.
Using another set of images , here is the panorama that I first get . The result is rather pleasing. If you would like to see the layers, click on and you will get this result . If you move the mouse and click on the layers, you will see the individual image .
If you notice that some elements are not perfectly vertical, use the Vertical Tool to manually draw vertical lines . This will help Autopano making a better result .
Once you’re done, you can even ask for an automatic cropping of the resulting image .
Autopano also adds HDR correction. I’m going to very briefly describe it. The result of selecting HDR might be a black image. This might has to do with the histogram, as well as individual adjustments. Select the Color Anchor tool , then click on one layer and choose “All to transfer function”. Once it’s done, use the Levels and move the white point until the histogram looks better .
On my example, I’ve lowered the white point quite a bit, because the dynamic range of all images wasn’t very high. When assembling source pictures that are already in HDR format (i.e. having a very wide dynamic range), it is very useful to work with a logarithmic curve instead of a linear curve. This can be done by double-clicking on the Levels Histogram. The sliders will then adjust to a logarithmic scale. There are also several more options for you to explore.
HDR tends to somehow flatten the contrast of the image. Another easy way to adjust your exposure through the panorama is to set “Color Anchors”: an anchor defines how the corresponding image will be modified by the color correction algorithm. As an example, let’s start with four shots with various exposure . There is a dramatic luminosity difference between the pale sky and the black rocks in the foreground. The automatic conversion creates a pleasing image but the sky is too bright as compared to the ground. Playing with the levels would make a global adjustment and would affect at the same time the ground and the sky. To better control exposure locally, select the Edit Color Tool and right-click on the top image that contains the sky. From the pop-up menu, choose “Hard Anchor” : this portion of the panorama will now remain unchanged.
Please note that for the moment, all the other Anchors are set to “Transfer function”, which means that only the luminosity and contrast values will be adjusted for these areas of the panorama (you can adjust this by yourself by right clicking and use “All to transfer function”, if it is not the case on your panorama).
To better understand the difference between them, let’s set another Hard Anchor on the ground . Since exposure was correct on both of these images, the result is a panorama where both the sky and the middle of the image are correctly exposed and lit . You can of course make other Hard Anchors to locally fine-tune exposure as you like. Note that the proper blending is still performed between the images, and that all transitions are smooth. The resulting panorama has better local contrast than the automatic result that we initially got.
That’s it. Autopano Pro offers many more ways to control exposure, as well as adjusting and moving images around to fine-tune the result. But it is also quite an easy tool to quickly automatically create panoramas from your work.
Where to Buy
Autopano Pro is available directly from the manufacturer’s web site for about 145USD.
Jean-Sébastien Monzani is a Swiss and French full-time freelance
photographer and graphic designer. Elegance, simplicity, a strong sense
of composition and emotions are key elements in his work. His images are
often constructed as photo-series—something between fashion
photography and movie storyboards. The sequence of shots usually tells
a little story but each image also works independently. Since he often
tries to convey atmosphere in his photos, he mainly shoots
on-location, almost exclusively in Lausanne, Switzerland, where he lives.
Example Images from Jean’s Gallery
Text ©2008 Jean-Sébastien
Monzani. Photos ©2008 Jean-Sébastien Monzani.