Bitmap or Grayscale Masks
You can also use Fireworks objects to mask bitmap images. This lets you create a vignette or a non-rectangular shape around the scanned image.
To use objects to mask a scanned image:
Choose Modify > Exit Bitmap Mode. This ensures that you are working with the image as an object, not as a bitmap image (Figure 11).
An object can also be used to mask a scanned image.
Create the items you want to act as the mask.
Use the Feather command in the Fill panel to add a softer edge to the mask.
Select the items and choose Edit > Cut.
Use the Pointer tool to select the image.
Choose Edit > Paste as Mask. The scanned image appears inside the mask (Figure 12).
The feathered edge of the mask makes the edge of the scanned image fade.
You can also use the grayscale values of a vector object to create the mask. Dark colors make the mask more transparent. Lighter colors make the mask less transparent.
Use this technique with gradient fills to create an image that fades from full strength to invisible.
To create a vector object grayscale mask:
Position the vector object to be used as a mask on top of the objects to be masked.
Select all of the objects.
Choose Modify > Mask > Group as Mask. This sets the top object as a grayscale mask and groups the other objects (Figure 13).
The Grayscale Appearance uses the black and white areas of the gradient inside the ellipse as the mask of the starfish image.
Just because you originally created a mask set to Path Outline doesn't mean it has to stay that way.
To convert a mask into a grayscale mask:
Use the Pointer tool or click the Mask Thumbnail to select the mask.
Choose Window > Object to open the Object panel.
Check Grayscale Appearance (Figure 14). The grayscale values of the image control the visibility of the masking objects.
The Vector Mask settings in the Object panel.
Just as you can use a gradient's grayscale values as a mask, you can also create a very sophisticated effect by using a bitmap image's grayscale values as a mask (Figure 15).
The effect of using a bitmapped image as a mask. Here the image of the clock is used as the grayscale mask for the image of the building.
To mask to an image's grayscale value:
Position the bitmap image you want to use as the grayscale mask over the objects or images that you want to be masked.
Select all the objects.
Choose Modify > Mask > Group as Mask. This sets the top object as a grayscale mask and groups the other objects The bitmapped image appears in the Mask Thumbnail (Figure 16).
A bitmapped image as a mask as seen in the Layers panel. The mask thumbnail shows that the image is automatically inverted.
Stop Destroying Innocent Pixels One of the most important reasons to mask a scanned image, rather than cutting or cropping, is that you preserve the original pixels in the image. The benefit of the mask is that you still have the original image to go back to - not so if you delete.
There's one last option for using a bitmap image as a mask - use the alpha channel transparency as the mask shape. This is very useful when you have a bitmap image with a unique shape on a transparent background. You can use the image's shape to mask other objects.
To mask to an image's alpha channel:
Position the image you want to use as the grayscale mask over the objects that are to be masked (Figure 17).
A bitmap image is positioned over objects in preparation for creating an alpha channel mask. Notice there is an alpha channel transparency around the shape of the butterfly.
Choose Modify > Mask > Group as Mask. This converts the image as a mask set for Grayscale Appearance.
Click the Mask Thumbnail in the Layers panel. This selects the bitmap image.
The Alpha Channel setting lets you use the transparent areas of a bitmap image as a mask.
The result of applying the Alpha Channel as a mask. Notice that the objects can be seen only within the shape of the bitmap image.