PROCESSING

APY Masterclass: Create a skyscape panorama

Processing an image to showcase the sky and a foreground

Never could I have magined that my ‘Château de Chambord’ image would be shortlisted in the Astronomy Photographer of the Year Competition 2021. It was captured in 2020 when I travelled 4,500km by car, with the goal of reaching five locations in five nights, and Château de Chambord (at Chambord, Centre-Val de Loire, France) was the last location on the itinerary.

The idea for imaging this beautiful location came from a photographer, Ralf Rohner, and if it wasn’t for him this photograph would have never been taken.

The image is a panorama and both the foreground and sky sections consist of multiple images. For both these, the camera had to be panned between each

Advice from a 2021 shortlisted entrant in the ‘Skyscapes’ category shot, with enough overlap to avoid stitching issues in post-processing. Each frame overlaps by 40 to 50 per cent to be on the safe side. By taking exposures at various settings, both the foreground and sky could be exposed correctly, which isn’t possible in a single image. Here I’ll explain, step by step, how these images are processed to get the final panorama.

Stitching together

The first step is to stitch the sky and foreground panoramas separately in Adobe Lightroom. Once the images are imported into the ‘Lightroom Catalog’ (see Screenshot 1) you can begin making adjustments. To do this, select any image, then from within the ‘Develop’ module in the top menu, chose the ‘Lens Corrections’ panel, which is located on the right-hand side towards the bottom. At the top of the panel are two tabs, ‘Profile’ and ‘Manual’. Select the ‘Profile’ tab and untick the ‘Enable Profile Corrections’ option below it. Next, select the ‘Manual’ tab and manually remove the ‘Vignetting’ by using the sliders, which prevents dark patches appearing in the final panorama.

Next, these adjusted settings need to be applied to batches of images (a batch each for the foreground and sky). To do this, first select the foreground images, then right-click with the mouse to bring up a dropdown menu and choose ‘Develop Settings Paste Settings’. Now all the images have the same settings applied to them. Next, reselect all the foreground images and right-click with the mouse again to bring up the dropdown menu. From this menu, select ‘Photo merge > Panorama’. Repeat these steps to stitch the sky images together.

Once the foreground image is stitched, proceed to the ‘Basic’ section in Lightroom – also located under the ‘Develop’ module – and use the sliders to adjust the ‘Whites’ balance levels, bringing them more to your liking. ‘Shadows’ can also be raised to increase dark areas, and ‘Highlights’ lower to reduce harsh bright areas. The stitched image is now ready to import into Photoshop, so select it, right click and chose ‘Edit in > Edit in Adobe Photoshop’.

With the image open in Photoshop use its ‘Quick Selection Tool’, located in the toolbar on the lefthand side, to highlight the foreground. Now add a Vector Mask to cut out the foreground, and make the sky in the image turn transparent: click on ‘Layer’ in the top menu and select ‘Vector Mask’ > ‘Reveal All’ in the dropdown menu. With the Vector Mask selected, choose a paintbrush from the toolbar to make fine adjustments. You need to use the colours black and white and can use ‘X’ on the keyboard as a shortcut to switch between them. Once the area of the mask is mastered (see Screenshot 2), it’s time to move on to the sky image.

Back in Lightroom select the sky image, with the foreground masked out (see Screenshot 3). Within the ‘Develop’ module you can correct the ‘Whites’ balance with the ‘Basic’ section. By boosting the ‘Saturation’ slider to maximum, you can see if the image is too warm or cold, and tweak until you get a neutral white balance. After sliding the ‘Saturation’ back to normal, right click and select ‘Edit in > Edit in Photoshop’.

Back in Photoshop, the next task is a star reduction to make the Milky Way stand out in the sky image.

Start by creating a duplicate layer of the original: select ‘Layer > Duplicate Layer’. Then, in the ‘Layers’ panel, select ‘Channels > Select’ and drag the RGB channel to the ‘marching ants circle’ – the selected marquee area – which will load the layer as a selection. Now hit ‘Select’ in the top menu, click ‘Modify > Expand’ in the dropdown options and input a value of 1 pixel. Choose ‘Select’ from the top menu again and click ‘Modify > Feather’, inputting 0.5 pixels. Back at the top menu, select ‘Filter > Other > Minimum’ and input 0.4 pixels. Now the star reduction is complete, toggle the ‘Opacity’ level of the layer on top to meet the desired result. Next, create a ‘Brightness/Contrast Adjustment’ layer to raise contrast levels, and a ‘Curves Adjustment Layer’ to raise bright tones and lower dark tones. You can also create an ‘S curve’ on the tonal range graph.

Now the sky is ready to blend with the final foreground image. To do this, select all the layers to be merged in the ‘Layers’ panel by holding down the Ctrl key, and then right-click with the mouse to show the ‘Merge Layers’ option. Then copy and paste this sky layer beneath the foreground layer. Once done, the sky is revealed behind the castle, and all that remains to create the final image is to move it into the correct place.

3 QUICK TIPS

1. Check out the sky replacement tool in Adobe Photoshop; it’s great for beginners who are getting into blending skies and foregrounds together for the first time.

2. For reflections of stars on water, expose no longer than you normally would for a sky. Try a small stack too, to reduce noise (unwanted artefacts).

3. With bright lights or objects on foregrounds, try shooting in the blue hour, or doing an HDR (high-dynamic range) stack.

ALL PICTURES: BENJAMIN BARAKAT