Stitching image panoramas in Photoshop CC – Guest post by Nick Williams
When most people create stitched panoramas in Photoshop, they usually jump straight to the PhotoMerge plug in. Although this is a quick and easy way to merge different exposures together, it’s also very automated.
In this tutorial we will show you how to get the best control when stitching different images, by exploring the Auto Align and Auto Blend Layers features in Photoshop CC. Along the way we’ll also discover some other cunning uses for these commands – creating image background extensions and merging disparate images together for photo compositing work.
Step 1
In many ways, step 1 begins at the shooting stage for the project, by capturing the different images which you’ll use to create the stitched panorama. You can use almost any camera to create the images needed to stitch a panorama in Photoshop, but there’s some things that are good to bear in mind when you’re out in the field shooting your source images.
Although you can take your images handheld by panning around the scene, it’s important to keep the camera level as you shoot, so having the camera locked down on a tripod makes things much easier. If you intend to do a lot of panorama work, you can invest in a dedicated tripod head that creates perfect alignment between images, but in most cases Photoshop produces pretty good results with a regular camera tripod head.
As you shoot, it’s also good to make sure you’re working in the camera’s manual focus and manual exposure modes. We don’t really want to see changes of focus position or depth of field in each image.
And finally, all panorama software work by looking for similar content in each image, so it’s vitally important that you overlap each image you take with the previous one by a minimum of 15-20%. We usually recommend shooting with a lot more overlap than this as you pan around a scene. Where you’re back in Photoshop, select the best ones from the overall sequence.
Step 2
Once you’ve shot the images that you want to merge together, the first step is to assemble them as a series of different Layers in a single Photoshop document. Thankfully you don’t have to do this by hand as the Adobe Bridge program provides a too to automatically stack the images for you.
From Photoshop use the File > Browse in Bridge command. Navigate to the folder containing the images you want to merge and select them in the Content Pod by using the Cmd/Cntl + A shortcut:
Go to the Tools menu > Photoshop > Load Files into Photoshop Layers command:
Once completed, you’ll end up with a new Photoshop document containing each selected image stacked on individual Layers:
Step 3
Next we’ll let Photoshop analyze the content of each Layer and work out it’s correct position in the panorama sequence using an automatic alignment command. Use the shortcut Cmd/Cntl +Alt +A to select all document Layers. Go to the Edit menu > Auto Align Layers command:
The dialog box provides a range of different projections, used to assemble the panorama with the best alignment between images. Image projections are necessary whenever you’re trying to map a spherical scene (such as the individual images taken as we’ve panned around our scene) onto a 2 dimensional surface (our Photoshop document). In order for the content to align correctly, we need to add some form of shape distortion to each image in the sequence. The three common choices for panoramic stitching are the Cylindrical, Perspective and Re-position methods.
To some degree, you should treat the projection methods as a creative option. Select each one in turn and Press OK to judge the results, but keep in mind the following differences between each method:
Perspective: this method adds perspective shaped distortion to each image in the sequence to create the correct alignment and produces a result similar to shooting the scene with a very wide angled lens. Good for stitching 2-3 images together, but the distortion can become exaggerated if stitching very wide views.
Cylindrical: adds a curved shape distortion to each image to align them correctly. This is a better choice if panning very wide views, but straight horizontal lines in the image may appear curved in some cases.
Re-position: this method does not add distortion to each image, but creates the best alignment possible between Layers by moving each image horizontally or vertically instead. This method doesn’t produce good alignment when you pan around a scene capturing your images, but works very well if photographing using a tilt/shift lens on a camera, where the camera body will have not been rotated as the pictures were taken.
In this example, as the source images were taken with a Shift Lens, the Re-position method produced the best results once the command was applied:
Step 4
Once you’ve found the best Projection method for the panorama, you’ll still notice some visible joins in the image, as you can see above. Often these may be caused if the camera exposure controls altered between each image you took, or if the alignment option couldn’t pin all parts of the image together accurately enough. To remove the visible seams, we’ll run a second command over the selected Layers, and in many cases this is where the magic happens !
Go to the Edit menu > Auto Blend Layers command. Make sure the Panorama Blend Method is selected and click OK to apply the command:
The Auto Blend Command will compare both content and colour differences between each Layer and selectively grade the best bits of each image together to a seamless result:
You’ll notice in the Window menu > Layers Panel that Photoshop creates a series of Layer Masks for each Layer, selectively hiding or showing the correct parts of each image.You shouldn’t need to alter the Layer structure at this point, so keeping the Layers selected, use the shortcut Cmd/Cntl +E to Merge them to a single Layer:
Step 5
Around the edges of the panorama you’ll always notice some extra transparency. Sometimes you’ll get larger transparent areas than shown here, particularly if you’ve used a Perspective or Cylindrical Projection style. In our example used here, you’ll also see some dark fall off from the camera lens as it was shifted to the far edge of the image circle.
Rather than cropping the image to remove the problems, we’ll now use the Auto Blend Layers command again to build up the image towards the edges using some applied technique:
In the toolbox, select the Polygonal Lasso tool. To extend the image at the bottom of the document, we begin by making a small selection of an area of ground:
Use the shortcut Cmd/Cntl +J to copy this area on to a new Layer. Using the Move tool (V) and re-position the copied image so that it covers up a transparent part of the document, overlapping a little with the existing image:
Use the Shortcut Cmd/Cntl +Alt +A to select both Layers. Go to Edit > Auto Blend Layers command. Click OK using the default settings:
Once the area has been blended, Use the shortcut Cmd/Cntl +E to merge the two selected Layers back together. If you notice repeating patterns being created between areas of the image which have been duplicated, use the Clone tool (S) or Healing Tools (J) to remove any obvious repeats once the Layers have been merged:
Continue to repeat the above steps, slowly building up the image towards the edges of the document, but leave the sky areas until the next step. Remember to Merge the Layers together each time you’ve run the Auto Blend command, and before you copy the next piece of the image:
Step 6
As we can see, the Auto Blend command does a really good job of removing visible edges and seams between different Layers, and most importantly it doesn’t only work when re-using parts of the same image. In this step we’re going to use the Auto Blend commands to help us composite a new and more dramatic sky in to our panorama from a different photo.
In order to produce an effective and realistic composite, it’s important to source an image taken under reasonably similar conditions, from a similar viewpoint and at a similar time of day, such as the example used here.
Open the image and use the Polygonal Lasso tool (L) to select the sky area. The selection doesn’t need to be perfect as the image edges will be blended anyway, but make sure you don’t miss off any part of the clouds around it’s border edges:
Use the Edit menu > Copy / Paste commands to transfer the new sky into your panorama image, and use the Move tool (V) to position it in the top half of the image:
Unfortunately, we can’t just blend these 2 Layers together directly. When compositing disparate images together using the Auto Blend commands, you’ll need to first create transparency in the underlying image by deleting the existing sky.
In the Window menu > Layers Panel, hold down the Cmd/Cntl key and click on the thumbnail for the new sky Layer you’ve created to load it’s content as a selection. Go to the Select menu > Modify > Contract command and shrink this selection by 10-15 pixels to provide an overlapping area between the 2 Layers:
We don’t want the large rocks to also be deleted, so we’ll subtract it from our selection where it overlaps in the image. Press the ‘5’ key on the numeric keypad to lower the Opacity of the new sky Layer to 50%. With the Polygonal Lasso tool (L) hold down the Alt. Key and trace a new selection around the edges of the rock to remove it from the first selection:
In the Layers Panel, select the background image Layer and press the backspace key to delete the original sky image:
Use the shortcut Cmd/Cntl +D to remove the selection. In the Layers Panel, click on the new Sky Layer and press ‘0’ on the numeric keypad to return the Layer Opacity to 100%.
Now we’re ready to blend our new sky into the scene. Use the shortcut Cmd/Cntl +Alt + A to select both Layers. Go to the Edit menu > Auto Blend Layer command. Click OK with the default settings applied:
Step 7
As you can see, Photoshop does a really good job of compositing the new sky into our scene. As a finishing touch, we’ll add a little more drama by adding a graduated contrast effect over the sky.
Go to the Window menu > Adjustments Panel. Click the Curves shortcut icon to create a new Adjustment Layer above the composite image:
In the Window > Properties Panel, click on the Curve graph line to add an anchor point as a midtone adjustment value and drag downwards to lower the brightness of the image:
We’ll edit the Layer Mask on the Adjustment Layer to fade the effect, so that it only adjusts the upper half of the image. Press the ‘G’ key to select Photoshop’s Gradient Fill tool. Check the Foreground/Background colours in the Toolbox, and if necessary, press the ‘X’ key on the keyboard to make White the active Foreground colour.
In the image, click and drag a line downwards from the top of the image, holding down the Shift key as you draw to snap the Gradient tool to a straight line. Release the mouse close to the horizon:
And here is a view of the finished result:
Nick works on Acuity Training’s Photoshop courses at their London & Guildford locations. When not teaching others; Nick spends his time learning to code and thinking about writing short stories.
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