Zoom In on the Best Image pg 5: Production Graphics with Wendy Peck at webreference.com | WebReference

Zoom In on the Best Image pg 5: Production Graphics with Wendy Peck at webreference.com


Zoom In on the Best Image: Removing Backgrounds

Similar backgrounds can help to unite images in a series.

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.


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.

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.


Layer duplicated and original layer filled with new background color.


Final selection to remove background.

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.



Edge pixels still hold some background color.

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.


Dodge and Burn tools (top) and Blur and Sharpen tools in Photoshop.

Retouch Tool Options window in Paint Shop Pro.

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.



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

Front page2345

Created by Wendy Peck,
URL: http://www.webreference.com/graphics/column50/
Created: July 21, 2001
Revised: July 21, 2001