Creating 360 Degree Panoramic Scenes in Photoshop
A 28mm wide angle lens has a viewing angle of around 76° degrees, a circular fisheye lens will give you a 180° viewing angle, and a wacky distorted image, but as far as I know there’s no such thing as a 360° lens (yet). This limitation makes it a little difficult in creating 360° panoramic images of your favorite horizons. Fortunately if you take stand in one spot and rotate incrementally while taking multiple images, each one overlapping the next by about a quarter, they can be imported into Photoshop (CS3 anyway, I’m not so sure about earlier versions) and merged together quite seamlessly.
The procedure is simple but there are a few options to choose from. First of all we have to choose our images. To illustrate I’m going to use some photos I took while on the top of Benbulben (a small mountain in Ireland). The final image itself is far from spectacular: it’s mostly just grass, but that’s not the point here – I want to show you how overlapping images (of any sort) can be combined. Here are the images I’ve chosen to merge:
The procedure is simple but there are a few options to choose from. First of all we have to choose our images. To illustrate I’m going to use some photos I took while on the top of Benbulben (a small mountain in Ireland). The final image itself is far from spectacular: it’s mostly just grass, but that’s not the point here – I want to show you how overlapping images (of any sort) can be combined. Here are the images I’ve chosen to merge:
With Photoshop open go to File -> Automate -> Photomerge. We are now presented with this box:
Immediately we can see on the left five options for merging our images and options for selecting the images themselves. For most people, myself included, choosing ‘Auto’ from the left-hand-side options is usually the safest way to go – Photoshop does a great job in stitching images together and most of the time the process is seamless. For completeness sake however I tried combining my images using each process to see what results I could get.
1. Auto
As expected Auto merging has done it’s job well: from the image below we can see, or rather can’t see, any sign of stitching between each photo. What Photoshop has done here is place all the image files onto their own layer, on one large canvas (see right) and searched for similarities between each image. Depending on how much similarity Photoshop finds between each one, it arranges them accordingly and applies a mask layer to each layer. Finally Photoshop removes any part of the photo that isn’t useful, usually any sections near the interface of two fo the images, as well as the rest of the canvas for that layer. This can take a while for Photoshop to do – for this example it took about 10 minutes or so. Choosing the auto option has the advantage of using a ‘click and forget’ approach: it gives very good results but you can’t fine tune the image positioning if you feel you need to. Personally I think the panoramic shot below would be far better if I could centre the view on the right had side, leaving the grassy sections on the outer edges of the shot. I’ve left the image uncropped so you can see how much you can typically expect to lose from each photo when you actually do the cropping.
As expected Auto merging has done it’s job well: from the image below we can see, or rather can’t see, any sign of stitching between each photo. What Photoshop has done here is place all the image files onto their own layer, on one large canvas (see right) and searched for similarities between each image. Depending on how much similarity Photoshop finds between each one, it arranges them accordingly and applies a mask layer to each layer. Finally Photoshop removes any part of the photo that isn’t useful, usually any sections near the interface of two fo the images, as well as the rest of the canvas for that layer. This can take a while for Photoshop to do – for this example it took about 10 minutes or so. Choosing the auto option has the advantage of using a ‘click and forget’ approach: it gives very good results but you can’t fine tune the image positioning if you feel you need to. Personally I think the panoramic shot below would be far better if I could centre the view on the right had side, leaving the grassy sections on the outer edges of the shot. I’ve left the image uncropped so you can see how much you can typically expect to lose from each photo when you actually do the cropping.
Automatic Photomerging – Click for larger image: about 500kB
2. Perspective
Tyring to photomerge the images using the Perspective option didn’t fare so well – I got this message half ways through the merging process:
Tyring to photomerge the images using the Perspective option didn’t fare so well – I got this message half ways through the merging process:
Some images could not be automatically aligned.
Choosing perspective is useful if there is a good sense of distance in your shot. Using the Interactive Layout option later on I was able to apply perspective to some of the images (albeit with another error) that you can see below.
3. Cylindrical
If you wish to create a panoramic image in which you want to exaggerate curvature, for example the horizon of the earth shot from a plane or a mountain top, then you should try using Cylindrical Photomerging. I don’t think it applies to the photos here but I’ve used it quickly anyway for completeness sake.
If you wish to create a panoramic image in which you want to exaggerate curvature, for example the horizon of the earth shot from a plane or a mountain top, then you should try using Cylindrical Photomerging. I don’t think it applies to the photos here but I’ve used it quickly anyway for completeness sake.
Cylindrical – Click for larger image: about 500kB
4. Reposition Only
The reposition only option allows you to move each image once Photoshop has finished merging them, so if for example you feel one could be positioned a little bit better you are free to do so, but Photoshop won’t re-blend afterwards which means you’ll have to alter the mask layer yourself if needs be. Sounds like a lot of hassle for very little gain in my opinion. You can see in the thumbnail below the gaps between each image – they won’t show up after you save
The reposition only option allows you to move each image once Photoshop has finished merging them, so if for example you feel one could be positioned a little bit better you are free to do so, but Photoshop won’t re-blend afterwards which means you’ll have to alter the mask layer yourself if needs be. Sounds like a lot of hassle for very little gain in my opinion. You can see in the thumbnail below the gaps between each image – they won’t show up after you save
Reposition Only – Click for larger image: about 500kB
5. Interactive Layout
The interactive layout option gives you full control in positioning each image and applying perspective. It will also try to blend each image again after repositioning, a big advantage over the Reposition Option.
The interactive layout option gives you full control in positioning each image and applying perspective. It will also try to blend each image again after repositioning, a big advantage over the Reposition Option.
You can easily see from the image below that even after I move each photo completely out of place Photoshop will do its best and try to blend them together anyway – something that won’t happen using the Reposition Only option.
I tried applying perspective here and while I still got an error…
Photomerge was not able to automatically correct the perspective for all of the images.
…photoshop allowed me to remove a couple of image and I was left with whats below. Unfortunately Photoshop has completely blown the long shot image in an attempt to add the perspective. I suspect this is because there is such a sharp change in distance from one shot to the next.
So if you have multiple photos then that you wish to merge into one long panoramic scene then you can try some of the option here that Photoshop has available. You can see the final shot here; like I said earlier it’s mostly just grass! I’ve made a slightly more interesting one from the top of Croagh Patrick that you can see here also!
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Removing Chromatic Aberrations (Colour Fringing) In Photoshop
Chromatic aberrations (commonly called colour fringing) are one of the most common and yet annoying photographic artifacts that occur in digital images. You’ll most likely find them in high contrast regions of your photos such as the edges of buildings or the branches of trees. They are caused by the fact that the visible spectrum is made up of not one but six monochromatic colours, (green, yellow, violet, blue, orange red) each with a unique wavelength. These differing wavelength alter the speed at which each colour enters a cameras lens, since the refractive index of the lens is wavelength dependant, and so dispersion of the colours can occur. This dispersion can be minimised by using specialist equipment such as an achromatic lens but that’s not much good advice if you’ve already shot a couple hundred pictures and now find green and purple fringing present. Don’t worry, there’s always hope! In Photoshop CS3 there are a number of ways to remove colour fringing with just a little effort.
1. The Sponge Tool.
The Sponge Tool in Photoshop can be used to either saturate or desaturate colour and is used in exactly the same way as the eraser, so is ideal if you want to remove small regions of colour fringing. It can be found in the tool bar as shown here on the right. Depending on Photoshop’s default settings the dodge tool or burn tool might be visible instead. Once you select the sponge tool you can set the brush size, choose saturate or desaturate, and choose the flow percentage (the pressure that the sponge is being pressed against the picture.) These settings should be visible just above the image, although it might be different on a windows machine – I am using a Mac. In any case, once you are satisfied with the setting you can sponge over the affected regions (using desaturate I would imagine) and gradually fade the fringing away to a non-noticeable greyish colour. It’s probably best to begin with a fairly low flow percentage (maybe 40%) and increase it once you gauge its effect.2. Adjustment Layers.
This is most effective if you want to remove a lot of fringing of a particular colour in one swoop. When you first open you image, if the layers palette is open (Window -> Layers), you image should be present and called Background. It will also have a lock symbol beside it. Double click the image to convert it to a layer. Then add a Hue / Saturation layer (either by Layer -> New Adjustment Layer -> Hue/Saturation or adding it from the options at the bottom of the layers palette). The box below should appear.
What we want to do now is, using the Saturation (and possibly the Brightness) scale, desaturate all of a particular color fringing that is causing us grief, e.g. purple. “Master” refers to the entire image so lowering the saturation will desaturate the everything – not what we want! Click edit and change it any other colour, it doesn’t really matter which one since we’ll be choosing the colour we want directly from the image using the eyedropper – make sure the first one is selected in the Hue/Saturation box (see above) and select the colour we want to desaturate. You might have to zoom in first. Alter the brightness also if the desaturation is too bright.
Once this step is complete a mask layer might be necessary if any desirable purples in the image were unintentionally desaturated. In the Hue/Saturation layer to the right we can see a second blank box. This is the mask layer and will negate the effect of the adjustment layer that it’s attached to – it masks it, geddit? There’s more to masks but for the moment all we have to do is select the paintbrush, choose black as the paint colour and brush over any region in our image that we don’t want to be affected by the adjustment layer (it’s a good idea to turn on and off the adjustment layer using the eye symbol beside the layer to see what parts of the image were affected and which parts we have to mask).
Once this step is complete a mask layer might be necessary if any desirable purples in the image were unintentionally desaturated. In the Hue/Saturation layer to the right we can see a second blank box. This is the mask layer and will negate the effect of the adjustment layer that it’s attached to – it masks it, geddit? There’s more to masks but for the moment all we have to do is select the paintbrush, choose black as the paint colour and brush over any region in our image that we don’t want to be affected by the adjustment layer (it’s a good idea to turn on and off the adjustment layer using the eye symbol beside the layer to see what parts of the image were affected and which parts we have to mask).
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