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© 1999 by Mike Bresciani. All Rights Reserved.
Creating a selection around objects is rarely as simple as using a single 'magic' technique. Rather it usually involves a combination of various techniques, followed by some handwork to clean up a little. With that in mind this tutorial will add another masking technique to your toolbox. The idea is to make it easier for the masking tools to select the objects by increasing the contrast between the item you want to select and the rest of the photo.
Before using this technique you will need to examine your image to see if there is some difference in brightness between the foreground and the background. Sometimes there is just not enough to work with, and another technique will have to be used. If there is some you can increase the difference by adjusting a copy of the image. Use whatever tool works best such as Levels, Posterize, Tone Curve, or Brightness/Contrast/Intensity.
If the image doesn't have much difference, then we can look at other possibilities. Like the color channels. Sometimes one of the individual channels will have more contrast, and you can copy the channel and increase the contrast of the copy to make the masking easier. Another option is to convert the image to another color mode, such as CMYK or Lab. Then using one of those color channels create the mask. Once the mask is created you can save the mask and revert the image back to its most recent save.
That's the basic outline of the procedure. In case you want to follow along I used several stock photos off the Corel CDs. The first one is located at Photos\Crc_fair\721013.wi. That's on CD #2 for the standalone version and CD #3 for the CorelDRAW suite version.
A word of caution: Never make the adjustments with the original. Make a copy and paste the copy into the image as a new object. Then make the adjustments to the new object. That way when you are done, just remove the object and your mask will be in place. Or if you want to be very cautious, duplicate the image. Make the adjustments, create the mask, and save the mask to your disk. Then load the mask into the original image.
Start by examining the image. Look for a foreground object that is either darker or lighter than the background. Or has a difference in colors. Each of these conditions is approached differently.
For this image there is a difference in colors between the whales and the water, so Color Masking will probably work. In this case we can make it easier though, by Posterizing the image first. Start by making a copy of the image. Then paste it in as an object. Make sure the object is active. Select the filter under Image/Transform/Posterize. Set the slider to its lowest value. Then work up from there. Sometimes the lowest value works best (as in this case), and sometimes you will need a larger posterize value to clearly define the colors. Remember to make the adjustments to the object, not the background.
The posterizing left out some of the edge. Paint it back in using black. Also, since we intend to use Color Masking based on the blue colors, check the whales for any blue in them. Again, just paint over them with black. Now selecting the colors for our Color Mask becomes simple.
You can find the Color Mask under the Mask menu. Click Reset. Then click on the eyedropper. Use this to select the colors from your image. Make sure the mask mode is set to plus, then click on the two large areas of blue. If you are dealing with a larger range of colors you can increase the tolerance by changing the number in the 'N' column.
Click on the eye icon and you will see the mask as you are building it. The red areas are the areas that will be masked when you apply the Color Mask, and the areas where you can see the images color will be the selection. This makes it easy to see which colors need to be added to the selection.
The mask won't be perfect, since some of the dark colors are the same as in the whales. Instead of worrying about them apply the mask then set the mask mode to minus and use the rectangle or the freehand masking tool to remove large areas that are away from the whales. Then zoom in and use the mask brush to get rid of the ones close to the whales.
Remove the object, Invert the mask, and it's ready.
Here is a different technique that also involves modifying the image to make it easier to mask the object.
This one is located at Photos\Crc_fair\721009.wi.
What I want to do is mask just the girl. Start by making a copy and pasting it back in as an object.
Now open the Levels dialog. It's under the Image/Adjust menu. We will be working with the two sliders located just above the histogram.
Make sure you are working with the object, and not the background.
We are going to use the white areas to define the mask. So watch the image and drag the top right slider to the left until the whites start to wash out. If you drag it too far you will get whites in the background. Like the ones showing up around the man in the lower half of the image. Keep an eye on the edges also, or you will get ragged edges, like those shown in the second image.
Now drag the top left slider over to meet the other one. If you need to fine tune the image, use the spinners in the top section.
There are still a few black areas we want to fill with white. A quick, easy way to do this is with the Magic Wand. Set the Magic Wand to a low tolerance setting. Select the black area around her waist. Then click on 'Similar' on the property bar. This will select all the black in the image. Since we are only going to use the girl we want to be able to separate the girl from the man easily. So change the mask mode to minus, and click on the man's hair. Then set the fill color to white, and using Edit/Fill, fill the selection.
We almost have our area we want to mask defined. But we can do something more to make it even easier. Click on the channels tab on your docker window. Look at each of the channels by clicking on them. You will notice that the red channel is almost perfect for masking the girl. Copy this channel. You do that just as you would anything else, select the channel and click on Copy under the Edit menu.
Note: Before you leave the Channels tab, click on the channel labeled 'RGB Channels'. If you don't when you go back to the objects tab your image will still display the channel you had selected.
Now click on the Object tab to go back. Paste the copy of the red channel as a new object.
Using the paint brush, select white as the fill color. Paint over the few dark spots in the area where the girl is. After you are done with that, select the Magic Wand. Set the tolerance to a low value and click on the white area we just defined. Remove the two objects, or make them invisible, and there is our girl perfectly masked and ready to be used wherever we need her.
Before copying the object add a small feather to the mask. Use Mask\Shape\Feather, with a small setting of 2 to 5, depending on your resolution. Set the curve to inside. Then copy the object.
Just a few more quick examples.
The Angel (in the Photo\Celebrtn folder) had good contrast in the red channel. So I copied that channel, pasted it in as an object, and used the levels filter. I painted out a few small black areas, which left a nice maskable area.
This one came from the Photo\Sports folder. I converted the image to Lab. Since the b channel had fairly good contrast. I copied that channel. Then before I pasted it in, I reverted the image back to RGB. Then I pasted the b channel that was still on the clipboard in as an object. Applied Levels, and painted over the black areas such as her bikini bottom, the sunglasses, and the lettering. Click on the white with the magic wand, remove the object and you will have an almost perfect mask.
Using CorelDRAW to Make Quilting Blocks · Creating a Painted Effect from a Photograph · Using Grayscale Masks in Corel PHOTO-PAINT · Adding Color to Black and White Photos With Corel PHOTO-PAINT · Fun With Photos -- Selecting Objects Part II · Fun With Photos -- Selecting Objects · Using Corel PHOTO-PAINT's Image Sprayer · 3D Web Buttons with Rolled Edges Tutorial · 3D Web Button Tutorial
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