Technique - How to Cut Out an Object in a Photograph.

example of a car partly cut out from its background. Introduction
Even if youíre not a Photoshop guru, there will come a time when you need to cut something out of an image. If you are a guru then cutting out will be second-nature and you can stop reading right here but if youíre taking your first steps in to the world of the digital eraser then read on. To cut out is to take an image file and remove, or erase, all of the unwanted detail around an object in the image so we end up with the object alone. We can then place that object against a new background such as pure white, as we did here in our example, or any you think appropriate for your project. Sounds simple and for the most part it is, requiring only bags of patience as you make your way around the object. However itís not simply a case of picking a tool and deleting the unwanted bits, so lets take a look at how we cut out.

The most important component of this process is the photo editing software youíll use to do the cutting out. I use Corelís Paintshop Pro but the tools are fairly standard across most editors youíll come across. Note though the names of the tools may vary. My go-to tool is the eraser.

Hard eraser shape example The Eraser
Place this tool over any part of the image, click the mouse and it will remove whatís underneath. Because the bits you want to erase could be a big or indeed small part of the image, the size of the eraser is configurable. When you activate the tool youíll be presented with the toolís options, one of which will be size. Stating the obvious here, but the more you want to delete, the bigger the tool should be made. If you have huge swathes of image to delete, use the bigger setting and if only a small portion is to be removed, use a smaller setting. There are other settings for the tool and weíll come to those shortly.

Once any large swathes of unwanted background have been eliminated, so begins the actual cutting out of the object against itís edges. To make the erase, the tool has to be placed in the area to be removed and against the edge of the object in the picture which is being retained. Click the mouse and the part of the image under the tool is removed. Whatís revealed below is important at this point. Photo editors use layers, think pages of a book laying on top of each other, but for now weíll park that and come back to layers later.

Configuring the Eraser
Whilst itís natural to think that at this stage we simply work our way around the object and continue to place the eraser tool in the right place and click, the erase tool may have to be reconfigured to match the exact erase action required.

Not only can the eraserís size be changed but so can the shape and harshness of the edge of the erase action. Chances are the default shape is round, but adjust the thickness and this shape can be reduced to that of a Rugby or American Football ball or reduce it further and it becomes even thinner and with more of a point. When it comes to the nooks and crannies around the object, the varying shape and size allows the tool to fit in to those spaces to make the erase.

If you have long, straight sections to cut, as I did on the top of back of the car, the eraser tool shape can be changed to give a flat edge by using the square-shaped eraser. By rotating the eraser it can be aligned with the straight edge to give an accurate cut along the flat section. All thats required is a steady hand to keep the cut in exact alignment with the last one to avoid a jagged edge. As we work our way around, the unwanted background is slowly removed the tool will continually be adjusted to best fit the erase area. example of a softer erase edge

Another important configuration is the Ďedgeí of the erase. This sets the hardness of the erase. Perhaps the best way to imagine how this might be used is to look at an object in an image to see how some parts are sharper than others. If youíre cutting out a particularly sharp part, then the edge of the eraser needs to be equally sharp to maintain that edge but if the part about to be erased is of a softer sharpness then the edge should be softened to match that softer edge. See the example where we have shown what a hard erase looks like compared to a softer edge. In our car image example, the front of the car was very sharp and so required that harder edge to the erase action but at the back of the car, which wasnít as sharply focussed, I needed the softer option.

Another useful feature is the rotate option. If the thickness of the eraser has been adjusted, then rotating it places the shape at different angles around 360 degrees. This means the tool can be positioned at precisely the right angle to fit those little corners.

reshaped eraser example Layers
Layers have many uses and Iím not covering those here but you should be aware of the effect of the layer when cutting out. (This applies to my experience of using Corelís Paintshop Pro, perhaps other editors deal with this differently).

When I bring an image in to the editor itís default layer is Background. If I start to erase a part of it, the editor prompts me to promote the Background to a full layer. This is not a big deal and it does allow you to add other layers which could be your new preferred background. As you can see in the before/after image, I have added a white background layer. In the final image, below, I also added some shadow under the car to make it look like it was actually standing on the white rather than as a floating object. The shadow is also on a layer. The beauty of layers is they can be switched on or off, moved up or down the layer stack, change opacity or even apply effects to layers below. Very useful. However all of those qualities will have to be explored another day.

final cut out image Other Things to Think About.
An objectís edges will always have an element of the original backgroundís colour so that has to be factored in. When applying the object to a new background, the colour of the edge may not look quite right.

Some things will look better than others when cut out. Try cutting out someone with long hair and you'll see how tricky this is. The whispy edge of the strands can be lost under heavy-handed eraser use. Itís not easy to tell if cutting out is going to work so I always try a little erasing first to see how those edges look. Completing a cut-out can be time-consuming so I want to be sure itís worth the effort.

There are other techniques to use when erasing which can speed up the process a little. My editor has a Ďmagic wandí selection tool which can be configured to pick the background and then make deleting it as easy as one click. This technique though works for some things better than others so again test to see if itís of any use.

Its useful to view the erasing process at 100% to see the erase edge. Viewing at less than 100% risks missing errors in our cutting out and missing the exact points to work on in the fine detail.

In the finished image, the car is fully cut out and set against a white background layer. To make the image more interesting and indeed more realistic, I added some shadow underneath the car. This gives the appearance of the car as if 'parked' there. Had I not added the shadow it would have looked like it was floating, which is of course fine for some situations, but here the 'parked' look was better.

Because there will always be occasions when we want an object but not the background, cutting out is a useful skill to learn. The eraser tool offers lots of functionality to make that task as easy as possible, requiring only a delicate touch, precision and patience.

To become proficient at its use, try cutting some things out, using all of the options to see how they work and indeed what doesnít work in various situations. A poorly cut out object is always obvious and looks bad. If weíre going to cut out something it should never look like itís been removed from another image and applied to a new background. It should look like it was always there and to make that work the cutting out must be top-notch. Remember, itís all about the edge and practice makes perfect.

All images © 2017 Peter Hatter and used with permission.

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