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Zoom In on the Best Image: Removing Backgrounds
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Similar backgrounds can help to unite images in a series.
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Removing backgrounds has been one of the more difficult tasks for graphic
artists since long before computers entered the art preparation equation.
 The
reason is obvious ... it just plain looks more professional, more energetic
to have a cutaway image on your page. Compare the image at the right
with the one at the left. Although the apple is identical, the one on
the right looks far more lifelike, and seems to blend right into the
text. The one at the left is much more static, even though it is still
an attractive image.
There are times when it is not appropriate to cut the background away.
A series of images is often better in a rectangular format to provide
consistency and relation. A circular image and a nearly rectangular
image will have very different visual weights, even if exactly the same
size, and may not look good together as part of a series. A similar
rectangular background can help to equalize visual difference. Note
how the image of three smaller apples is still tied to the single apple
image through the background.
Having said that it is not always necessary to cut the background away,
I gave an example that is better with no background so that you can
put your choice of background behind images. I suppose if I really tell
the truth, unless you are working with scenery shots, which of course
show a scene, usually, I cut the background away so that I can have
total freedom.
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Third Party Filters
Let me slip aside to discuss third party filters. I have nothing against
filters that promise to create perfect selections every time, letting
you remove backgrounds with one click. In my experience, unless you
are working with stripping backgrounds every day, I think you are better
to learn the manual techniques, for two very important reasons. First,
in order to be really successful with a filter, you usually must know
how to do the technique manually. Second, and even more important, is
that you use the techniques required to strip backgrounds for much more
than just that one act. Learn a plug-in, and you have ... learned a
plug-in. Learn the manual method and you have increased your selection
skill, perhaps your mask skill and have worked with many of the most
powerful Photoshop features.
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Cutting Backgrounds
You should also refer to several previous articles to get a full picture
of Photoshop selections and masks. Masks
Are Easy ... Really! discusses masks and how to use them. Pay special
attention to the Quick Mask section of this article. Photoshop
Selections: Back to Basics or
Paint Shop Pro Selections are
primers devoted to nothing but creating perfect selections in the respective
programs. PS and PSP Channels: What, When
and Why? will introduce you to channels, which can help you
to make easy selections in order to strip backgrounds.
So what exactly do you need to do to strip out a background? The simple
answer is: Select your background, apply a slight feathering effect
to the selection and press your delete key. As usual, reality is a little
different. The sneaky part of that simple description is the line: Select
your background. Easy to say. Often very difficult to do.
I start by looking at what part of the image is most selectable. I
prefer to work with the Magic Wand whenever possible. In fact, I usually
start by finding a Magic Wand setting that will select most of the pixels
in the background. I will then use my Shift key to select more areas
of differing colors until I have most of the background selected. Let's
step through selecting the background on a simple image. I have merged
the layers on the multiple apples image above and will select the textured
background to once again leave just the apples.
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Layer duplicated and original layer filled with new
background color.
Final selection to remove background.
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I start by duplicating the layer, and filling the background with the
eventual background color, in this case, white. As you strip the background
away, the white, or whatever your background will be will show progress
clearly.
 The
next step is the big one, stripping the background away. In this example,
the texture did cause some problems, as the texture is created by varied
colors. Magic Wand selection works by selecting similar colors. The
closer the subject colors are to the background colors, the more difficult
that the selection will be. In this case, the bottom right apple shadow
area is very similar to the background dark color.
The selection shown here is the result of several Shift selections
with the Magic Wand tolerance set for 30, with antialiasing turned on.
I will now use the other selection tools, with the Shift key to add
to the selection and collect the little areas in the background, and
with the Alt key (subtraction) to remove any stray selection areas on
the apple (see the lightest apple edge). The image at the left shows
a magnified view of one edge with the selection in place. Don't forget
to pick up any background that may be showing through the center of
the image. In this case, there is a tiny piece of green at the top of
the right apple.
Note: I also tried selecting the apples in this image. If they
had been easier to select, I could have inverted that selection. However,
it was no easier to select the apples than it was the background.
I suggest that you stop to save your selection at this point, or even
sooner in the process. Once you have invested many minutes of work into
the selection, save it and continue to update the saved selection as
you work. Photoshop Selections: Back to
Basics or
Paint Shop Pro Selections describe
how to save and retrieve a selection. You may never use the saved selection,
but it is such a simple process to save it, there is no reason not to
give yourself that little bit of insurance.
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Edge pixels still hold some background color.
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Often, you will find that there is a ghost of the current background
color all around the edge of the objects, the result of antialiasing
in the original image. See the image at the left, which shows a heavily
magnified edge with the background removed. If you will be placing the
object on a similarity colored background, this will cause no problem.
For this image, however, I intend to place it on a light background,
so the dark green edge must go. In many cases, this edge can be removed
by increasing the selection size by one pixel. This image can afford
to lose one pixel all around. You will have to try it with your image
to see if that is enough to solve the problem.
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Dodge and Burn tools (top) and Blur and Sharpen tools
in Photoshop.
Retouch Tool Options window in Paint Shop Pro.
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Once you have your selection perfect, you must soften the edge a little.
If you simply delete your image, you will find that the edges are hard,
and the photo looks like it was cut out. Usually, feathering the selection
by one pixel will accomplish the trick. Finally, delete the background.
Cleaning Up
There are several tools you can use to clean up any stubborn edges on
your image. Occasionally, a few pixels of the background color remain,
or even with feathering, the edge seems to hard. Apply the following
techniques with a light hand and a small, soft brush.
Blur tool: Use the blur tool to run along edges that are too
crisp, or are not blending well with their neighbors.
Sharpen: Once in a while one edge becomes a little too blurry.
Running over the edge with the sharpen tool will affect only that area.
Dodge tool: The color may be fine, but the edge pixels just
a little too dark. The Dodge tool magically lightens only the edges
you touch with the brush.
Burn tool: If the edge pixels in one area are a little to light,
call on the burn tool. Only the pixels you paint will be darkened.
Like most graphics techniques, there are no rules for photo composition
and enhancing. The only true way to build your knowledge and expertise
is to practice. Before long, the most difficult and confusing methods
become second nature, but you must put in the time. Use the methods
in this article as a guide and put that mouse to work.
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Back to start
Zoom In on the Best Image: Tutorial Index
Photo Composition for the Web
Know Thine Resolution
Taking Advantage of Resolution
Finding the Right Portion of an Image
Removing Backgrounds
 
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