Photoshop Gradient Tool: Blending Images
jean miele | Software Techniques | Published Mar 10, 2013
|This image was created from two separate photos, using Photoshop’s Gradient tool.|
Photoshop's Gradient tool may not be on most users' lists of go-to editing options. But it should be. In combination with layer masks, the Gradient tool lets you create natural-looking composite images. In this tutorial I'll show you how to combine a compelling foreground element with an interesting sky to create a seamless, believable landscape image.
In an upcoming article we'll explore how to use the Gradient tool to modify layer mask-enabled adjustments to brightness, contrast and toning. But first things first. Here, I'll show you how to make two separate images blend seamlessly into one.
When two is better than one
If your instinct is to resist the whole notion of composite imagery because it feels like 'cheating', you should know that the idea of combining pictures together has a long photographic tradition. Swedish photographer Oscar Gustave Rejlander pioneered the photomontage a.k.a. 'combination printing' in the 1850s! In addition to solving the problem of capturing both sky and foreground on the low-latitude, blue-insensitive emulsions of the day, many 19th century masters appreciated that combination printing is a wonderful way for photographic artists to realize their personal vision, just as painters do.
Here our goal is to seamlessly blend the two images below into a the single image shown at the start of the article. Since we're combining two images, you may be wondering why I don't just use the Quick Selection tool to cut the sky out of one image and paste it over the existing sky in the other image.
The problem is that masking or silhouetting the horizon line is much harder than you may think. The roofline won’t be a problem, and the soft edges of the mountains at the horizon are do-able, but those tree limbs and leaves will be a source of heartbreak! Chances are, even after hours of careful work using Channels, Image Calculations or the Pen tools, something will still look 'funny' around those trees.
So let’s just skip all that. Using the Gradient tool in a layer mask is fun, effective, and best of all, speedy. Of course, there are some projects that need a complex silhouette, but when you're blending things like sky and clouds, using a gradient is not only easier, but produces better results.
Layer masks and gradients explained
The concept of layer masks can be hard to grasp, even for experienced Photoshop users. So before we go any further, here’s a good, simple way to think about them. Masks have only one job: they hide stuff. A mask on a pixel layer makes it possible to hide parts of that layer without destroying any pixels. By using masks instead of the Eraser or History brushes, you can always change your mind about any edits because you're never deleting pixels, only changing their visibility. Better still, you can restore the visibility of any hidden items even after the image file has been saved, closed, and reopened.
When a layer mask is white, it reveals the layer to which it is attached. A black layer mask does just the opposite. It hides the layer to which it is attached. But of course, a mask does not have to be filled completely with black or white. And that's where gradients come in.
When making a gradient inside a layer mask, the thing to remember is that a black-to-white gradient means 'hidden-to-revealed' or 'invisible-to-visible'. A white-to-black gradient means exactly the opposite: 'revealed-to-hidden' or 'visible-to-invisible'.
Gradient tool options
When you select the Gradient tool there are two options you need to set: the gradient's colors and its shape.
|You can set the Gradient options to display as thumbnails or in a list view, at a choice of sizes. You can even opt for a text-only view to save room if you're working on a small monitor.|
In this tutorial we'll be using the Black, White option to fill in the layer mask. These are the colors we want to use to hide and reveal parts of the layer. The Black, White option is, by default the third item in the Gradient flyout menu shown above. Note that if you set Photoshop's foreground/background swatches to their defaults, (keyboard shortcut: D), then choosing the Foreground to Background option in the Gradient flyout menu will give the same effect.
You also want to make sure to select a Linear Gradient in the options bar. In a followup article on gradient masking, I’ll be using both the Radial and Reflected Gradients. (If anyone can tell me a practical use for the Angle or Diamond Gradients, I’d love to hear from you.)
|Once the Gradient tool is selected you can decide the shape of your gradient. You can apply it as a straight-line (linear), radial or reflected blend (shown here). For this tutorial only the Linear Gradient will be employed.|
I'll be honest, it takes a little practice to get the hang of using the Gradient tool and its options, but the idea is pretty straightforward. The Gradient tool (unlike a Gradient Fill or Gradient Map Adjustment Layer) is similar to the Brush tool. As with brushes, the color black in a mask hides stuff; white makes it visible. And as I'll demonstrate later, gray partially hides a layer.
Here's where gradients differ though. You create one by click-dragging. A longer click+drag results in a more gradual transition, a shorter click-drag creates a more abrupt transition. To experiment with the Gradient tool I suggest creating a new, blank canvas (File>New) and drawing different gradients on the white Background layer. It’s a great way to make sense of this very useful tool.
For this tutorial I've provided moderate-resolution JPEGs of both images you see below so that you can follow along each step of the way. Simply right-click on each to save it to your computer. Throughout the tutorial I'll refer to the image with the foreground homestead as Photo 1 and the image of the dramatic clouds as Photo 2.
|Photo 1||Photo 2|
These JPEGs are derived from Raw files which I edited so the overall contrast looked good and the color of the two skies was compatible. You'll want similar flexibility when you try this technique on your own images as well, so I highly recommend using Raw files as the basis for any composite work.
Bring the two images together as layers in a single file, with Photo 1 on the bottom and Photo 2 on top. An easy way to do this is to open both images in Photoshop in adjacent windows. Select the Move tool and, while holding the Shift key, click-drag Photo 2 onto Photo 1. Tip: Holding the Shift key until after you release the mouse will center align the image you're dragging.
Reduce the layer opacity of Photo 2 (here I chose 74%). Use the Move tool to adjust Photo 2 up and down to see how the two images look in relationship to each other. Once the alignment looks good (no mountains in the sky, and the clouds working together nicely), restore the opacity of the Photo 2 layer back to 100%.
|Here the two layers are being aligned, with the opacity of the top layer reduced to 74%, so that Photo 2 can be seen as a semi-transparent overlay atop the bottom layer. This allows you to position it properly.|
With the Photo 2 layer selected, add a layer mask to it by going to Layer>LayerMask>Reveal All. The resulting layer mask will be filled with white.
|A layer mask has been added to the top layer. Because the entire mask is white, the Photo 2 layer is still completely visible.|
If you’ve used brushes in masks before, using the Gradient tool follows the same idea. First, select the Gradient tool (keyboard shortcut: G) and in the Control panel set it to the Black, White option (see below). If you've skipped the first page of this article and jumped straight to Step 1, make sure you've read my earlier explanation of the Gradient tool.
|Choosing the Black, White option (circled above) means that any gradient you draw on a layer mask will first hide, then reveal the contents of the attached layer.|
With the Photo 2 layer active (meaning it's highlighted in blue), click-drag in the canvas, from above the house towards the top of the image. This will create a black-to-white gradient inside the mask. Since in a mask, black conceals and white reveals, the bottom of Photo 2 will be hidden and the top will remain visible.
I applied the gradient several times, at slightly different angles, dragging a bit further or a bit less until I created just the right gradient in the Mask. This is something you'll want to experiment with yourself over several attempts. Keep in mind, however, that gradients on a single layer are not cumulative. Drawing a new gradient immediately replaces the previous one.
|After the gradient is drawn on the layer mask, the bottom region of Photo 2 (the layer on top), becomes invisible, seamlessly blending with the Photo 1 layer beneath it.|
The great thing about using the Gradient tool is that the transition is smooth and gradual. Why? Because the gradient is not only applying black and white areas to the layer mask. It also introduces shades of gray in-between them to feather the blend. Gray values partially hide or reveal areas, allowing for a natural, subtle transition between the two layers.
Of course, I could have used selections for this job, or brushes, but a Linear Gradient is the perfect tool to mask a more interesting sky onto a great foreground. In fact, Linear and Radial Gradients mimic the makeshift cardboard tools we used for burning & dodging in traditional, chemical black-and-white darkrooms; they provide feathered, believable transitions – especially effective when used in Masks.
And with just three simple steps you can create a seamless blend like you see below. Spend just a little time practicing with the Gradient tool and you'll have a fast, easy technique for making composite images.
|Here's our 'combination-print' landscape, before and after.|
This is the first of a two-part tutorial so stay tuned for Part 2. We’ll do the 'darkroom' work this picture needs using the gradient tool with Adjustment Layers – and explore some of the Gradient tool’s advanced features.
Jean Miele has been digitally editing images for over 15 years. A working commercial photographer and highly sought after Photoshop instructor, his fine art images and workshop schedule can be seen at jeanmiele.com. You can also follow him on Facebook.