Widen Your Field of View Using Photo-merge
- Chris O'Shea
- Feb 26, 2020
- 3 min read
Updated: Jul 4, 2023
What is Photo Merge?
Photo merge is where a number of photographs are effectively ‘stitched together’ to produce a panoramic image that could not be achieved in one single shot.
Case Study
I wanted to capture the open expanse looking out across the Orwell estuary towards Felixstowe Docks but could not achieve this in one shot. I used a tripod with a pan head and set my Nikon D5100 to take 3 bracketed shots (different exposures) of each scene. To cover the complete view I took shots of 4 scenes (with a 30% overlap) and panned left to right so in total 12 photographs were required to produce the image above.
After post-processing each scene (of 3 exposures) using Photomatix Pro (see ’Widen your Dynamic Range to Take Better Photos’ Blog), I was left with four High Dynamic Range images that needed to be stitched together to achieve the final panorama. I used Photoshop CC photo merge function to load in the images to achieve the final panoramic image shown above.
Why use Photo Merge?
I recall standing on top of a mountain overlooking the lake district one day and thinking ‘how do I capture this magnificent scene’ as I do not want to loose the memory of what I can see when I head back home. Just one single photograph does not provide the field of view to capture the scene in one go so the only options are a wide angle lens or a mechanism to combine photographs seamlessly to capture the full scene. Wide angle lens are great in certain circumstances but I do not want to have distortion on the edges of the image - something that wide-angle lenses are prone too by their nature. Also, Stitch multiple sections together and you've dramatically increased your resolution, and thus your enlarging capabilities.
How to Photo Merge?
It is essential to use a sturdy tripod that is level to the ground. Take multiple photographs of the scene ensuring that each photograph overlaps by around 30%. If using a DSLR it is best to set to manual mode to avoid the camera changing the exposure settings, resulting in odd transitions between photographs. If you use a zoom lens, do not change the focal length (zoom in or out) while taking your pictures. If you plan to take multiple panoramas I suggest taking a 'dummy' shot between the panoramas so when it comes to post-processing, you know there is a series of images that comprise a panorama and it is easier to separate them out. As I may be taking different numbers of shots for each panorama and I may also be changing the lens as well, I use a card for the 'dummy' shot which simply states that its is a panorama and the type of lens I am using. This has helped enormously, especially when I have taken literally hundreds of photographs!
What equipment do I need?
As mentioned, a sturdy tripod preferably with a panoramic swivel head and a spirit level to check the level. You will also need post-processing software to combine the photographs into the Panorama. Options include Photoshop CC which is a subscription-based service, Photoshop Elements or alternatively open source (free) software is available from Hugin.
The four scenes (HDR images) shown below were used with Photoshop CC Photo merge to produce the final panoramic image.
Photoshop CC Photo merge selection menu is shown below. It is relatively simple to use. Just browse to where the photos are on your computer and choose the layout perspective. I choose Auto Layout and select Geometrical Distortion Correction and Content Aware Fill Transparent Areas. With Auto Layout, Photoshop analyses the source images and applies either a Perspective, Cylindrical, and Spherical layout, depending on which produces a better photo merge. Geometrical Distortion Correction compensates for distortion produced by the lens (for example barrel distortion). Content Aware Fill Transparent Areas seamlessly fill the transparent areas with similar image content nearby. Time to process depends on a number of factors including processing power and number of images, for the above example a seamless panorama was produced in less than one minute.
Here are a few other examples of output from using Photo-merge. Note that as the number of scenes increases, the file size can get quite large (i.e. much greater than 10 Mb!).
360 degree Panorama
It is possible to produce a 360 panorama and wrap around the image and upload to a 360 degree image viewer (Facebook has this capability & will recognise a 360 degree image). In order to produce a 360 degree panorama there are a few more things to consider. I will talk about this in a future blog.
I hope you found this blog useful. Constructive comments always welcome. Please note the photographic images that appear on this blog are not full/high resolution. High resolution images (plus many others) can be purchased as professional quality prints or mounted on various media through my on-line shop.
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