Compositing Multiple Images in Photoshop
I’ve been using Photoshop for image manipulation and compositing since August 15, 1992. How do I know it was that day? I actually found the first image I did on a backup tape and the creation date on the file was 08-15-1992. I have to tell you, it was garbage, literally. It was an image done for Waste Management depicting a waste cleanup effort that I shot in my studio. I did the Photoshop imaging on a rental Mac IIci with 32 MB of RAM and an 80 MB hard drive. I worked on a 24 MB scan and it was painfully slow—saving the image took about 30 minutes (and it didn’t even have layers). It was done using Photoshop 2.0.1. I started on a Friday evening, and my wife woke me up on Monday morning—I had fallen asleep on my keyboard. Figure 5.28 shows the final manipulated and composited image. See, I told you it was garbage.
FIGURE 5.28 My first Photoshop job, from August 15, 1992.
That first job was enough to get me hooked on digital imaging. Throughout the 1990s, I continued to do digital imaging and compositing commercially. If you want to see more, you can visit my website (www.schewephoto.com).
Enough nostalgia—let’s get back to the here and now. The images I’ll composite are two shots I captured in the county of Dorset in the southwest of England. The first image is a shot of Corfe Castle in a village of the same name. It was shot in late afternoon light with my Phase One camera and back with a 75–150mm lens. It’s a nice enough shot, but there were no clouds in the sky (unusual for that locale), so I decided to add some. Ironically, I had taken a shot of the Portland Bill Lighthouse on the Isle of Portland the previous morning in very early light that had some very nice clouds. That was also shot with the Phase camera so the resolutions would match up pretty well. Figure 5.29 shows the original shots (the Corfe Castle shot is cropped a bit from the sides and bottom).
FIGURE 5.29 The two images to be composited.
Creating the Composite Mask
I used Color Range to select the sky in the castle shot and saved the selection as a channel. The Color Range selection unfortunately picked up quite a bit of ancillary bits from within the castle that needed touching up. Figure 5.30 shows the original sky channel and the adjustments to the channel.
FIGURE 5.30 The Color Range selection saved as a channel and adjusted.
You can see that Color Range got some extraneous parts of the castle in the selection that would need to be cleaned up. I zoomed in and used the Pencil tool to paint black inside the castle perimeters. I find it easier to use the Pencil tool because it’s less likely to accidentally paint outside the boundaries, as might happen with a Paintbrush tool. Plus, the Pencil tool paints really fast. The final step was to apply a 1-pixel blur using the Gaussian Blur filter.
Compositing the Sky
After preparing the sky channel, I copied and pasted the entire lighthouse image into the castle shot. I loaded the sky channel as a layer mask and prepared to use Free Transform to size the lighthouse sky for the castle image. To be able to transform a layer with a layer mask, you need to uncheck the layer mask link to the pixel layer. Figure 5.31 shows the link indicator. To unlink the layer and layer mask, just click the link icon.
FIGURE 5.31 Unlinking the layer from the layer mask.
Once the layer mask was unlinked, I selected the image layer and used Free Transform to resize the sky of the lighthouse image to fit correctly on the castle image. I intentionally distorted the lighthouse sky to give it more perspective, which was slightly ironic since the castle was shot with a 75mm normal lens, whereas the lighthouse was shot with a 28mm wide-angle lens. I positioned the lighthouse sky so the actual lighthouse was just invisible. In doing so, I had a touch of the English Channel showing beyond the castle in the far-left edge. I didn’t think seeing the English Channel beyond the castle would be a good idea, so I used the Paintbrush tool to paint black in the layer mask to blend the water out and the original castle clouds back in. Figure 5.32 shows the two steps.
FIGURE 5.32 Resizing the sky and adjusting the layer mask.
The composite looked pretty good, but I wanted to adjust the lighthouse sky tone and color. To do so, I needed to create a mask based on the luminance of the sky image. Luminance-based masks are very useful for tone and color correction and are something I use often. To create a luminance-based mask, you can Command+click (Mac) or Ctrl+click (Windows) on the combined RGB channel icon or use the slightly obscure keyboard shortcut of Command+Option+2 (Mac) or Ctrl+Alt+2 (Windows). Once the luminance selection was created, I saved the selection to a channel. I needed to remove the castle area from the channel. While the luminance selection was active, I used the Load Selection command, selected the Sky channel, inverted, and used the Subtract from Selection option as shown in Figure 5.33.
FIGURE 5.33 The Load Selection dialog box and the options selected.
The result of the Load Selection command is shown in Figure 5.34, as is the original luminance-based channel.
FIGURE 5.34 The luminance-based channel and the Sky Luminosity channel.
After loading the Sky Luminosity channel as a selection, I used a Curves adjustment layer to lighten the sky and tweak the color of the clouds to warm them up. I also created an additional channel to use as a gradient-based Curves adjustment layer to darken the top of the whole sky. I added a Hue/Saturation adjustment layer to brighten the green grass and a final Curves adjustment layer to lighten the entire image. Figure 5.35 shows the final Channels and Layers panel. Figure 5.36 is the final composited image.
FIGURE 5.35 The final Channels and Layers panels showing the adjustment layers.
FIGURE 5.36 The final Corfe Castle composite.