Apple Numbers '09 - Manual (Page 198)

8 To change the size or position of the mask or the image within it, select the masked
image, and then click Edit Mask.
Repeat the steps above as needed.
9 To unmask the image, click Unmask in the toolbar (or choose Format > Unmask).
If you mask a very large image file and you need to use only the smaller version in
your spreadsheet, you can have Numbers keep only the smaller copy of the image,
thus reducing the overall size of your spreadsheet. See “Reducing Image File Sizes” on
page 198.
Reducing Image File Sizes
If you resized or masked a very large image file, and you want to save the image file
as part of your Numbers spreadsheet (so that you can easily transfer it to another
computer), but you want to keep the document size to a minimum, you can choose to
save only the smaller (cropped or shrunk) version of the image in your spreadsheet.
Before you reduce the image file size, you must save your document. For details about
how to do this, see “Saving a Spreadsheet” on page 32.
Here are ways to reduce the size of images:
To reduce the file size of an individual image that you masked or resized to a smaller
m
size, select the image and choose Format > Image > Reduce Image File Size.
To reduce the file size of all masked and resized (shrunk) images, deselect all elements
m
on the sheet, and then choose File > Reduce File Size.
Important: After you reduce the size of masked or shrunk image files, you won’t be
able to restore them to their original size. If you later want to restore their original size,
you must add the original image files to the document again.
Images used in image fills can’t be reduced in this way. Some types of image files also
may not be reducible.
To learn about reducing the size of audio and movie files, see “Reducing the Size of
Media Files” on page 212.
Removing the Background or Unwanted Elements from an Image
The Instant Alpha tool lets you to make parts of an image transparent in order to
remove the image background.
You get the best results removing solid colors with clear boundaries around them.
To remove areas that are less distinct, select a smaller area and repeat the process.
To remove unwanted elements:
1 Select the image.
2 Choose Format > Instant Alpha.
198 Chapter 9 Working with Shapes, Graphics, and Other Objects