Selecting Pixels in Images

When a paint object is in Edit mode, any filters, commands, and painting tools that you apply can affect the entire image. When you have selected pixels in the image, the effect of a tool, filter, or other adjustment is confined to the selected pixels.

You can select areas in an image using painting tools or menu commands. For example, you can make rectangular selections by dragging the Marquee tool in an image, and you can use the Color Range command to select groups of pixels based on color similarity.

Selection Borders

The selected pixels in an image are referred to collectively as a selection. When you make a selection, Canvas X Draw surrounds the selected pixels with a moving dashed border. You can hide and display the border without affecting the selection.

To Hide the Border:

Choose Image | Select | Hide Edges.

To Display the Selection Border:

Choose Image | Select | Show Edges.

Deselecting an Image Selection

When you use a selection tool in normal mode, making a new selection replaces any existing selection in an image.

To Deselect Pixels without Making a New Selection:

Choose Image | Select | None. You can also press Esc to deselect a selection. If a selection is floating, pressing Esc once defloats the selection; pressing Esc again deselects all pixels.

Selecting All Pixels in an Image

You can apply painting tools and filters to an entire image without first making a selection. But you can also select all the pixels in an image when you want to work with them as a selection.

To Select All Pixels, with a Paint Object in Edit Mode:

Choose Image | Select | All. A selection border appears around the entire image.

Using Pixel Selection Tools

Use the Marquee, Oval Marquee, Row Selection, Column Selection, and Lasso tools to select areas in images. In the Painting tools (click the Paintbrush tool), select the Marquee tool to access the Pixel Selection tools.

You can view the dimensions of your selection in the Status bar.

The Marquee tool selects rectangular areas. The Oval Marquee tool selects oval areas. The Column Selection tool selects a single vertical column of pixels. The Row Selection tool selects a single horizontal row of pixels. The Lasso tools selects odd-shaped areas.

The Marquee, Oval Marquee, Row Selection, and Column Selection tools are located in a tool palette within the Painting tool palette. The Lasso tools are separate icons in the Painting tool palette.

These selection tools let you select any part of an image, from one pixel to all the pixels in the image. By using modifier keys with these tools, you can add to and subtract from selections, and select the overlapping area of two selections.

By subtracting a circle from a larger circle, for example, you can make a ring-shaped selection with an unselected area inside. See Modifying Selections.

To Select Rectangular or Oval Areas:

1. Place the paint object into Edit mode.
2. Select the Marquee tool or the Oval Marquee tool.
3. Drag diagonally in the image; a selection rectangle or oval expands as you drag away from the starting point. When you release the mouse button, a dashed border outlines the selected area.

To Make a Square Selection:

If no selection exists, press Shift and drag the Marquee tool in an image. If a selection exists in the image, pressing Shift adds to the selection.

To Make a Circular Selection:

If no selection exists, press Shift and drag the Oval Marquee tool in an image. If a selection exists in the image, pressing Shift adds to the selection.

To Expand a Selection Marquee from the Center:

If no selection exists, press Ctrl and drag the Marquee or Oval Marquee tool. You can press Ctrl+Shift to constrain the selection marquee and expand it from the center.

To Select Single Rows or Columns:

1. Select the Row Selection tool or the Column Selection tool. If the paint object isn’t in Edit mode, click it.
2. Click a single pixel to select all pixels in the same row or column in the image. A dashed border outlines the selected row or column. Or, press and hold the mouse button to see a selection outline, and move the pointer to position the selection outline. Release the mouse button to set the selection, and a dashed border outlines the selected row or column.

When working in high-resolution images, you can zoom to 400% magnification or higher to see the pixels you want to select.

To Select Areas with the Lasso Tools:

1. Place the paint object into Edit mode.
2. Select either Lasso tool.
3. Drag in the image to outline a selection. Canvas X Draw connects the starting and ending points with a straight line. A dashed border outlines the selected areas.

Lasso Options

To set options before using the Lasso tools, use the settings in the Properties bar.

Modifying Selections

After you make a selection using any selection technique, you can use modifier keys to alter the selection with the Marquee, Oval Marquee, Row Selection, Column Selection, and Lasso tools.

To Add to a Selection:

Press Shift when you use a selection tool. A “+” symbol indicates that the tool will add the new selection to the existing selection.

To Subtract from a Selection:

Press Ctrl when you use a selection tool. A “-” symbol indicates that the tool will subtract the new selection from the existing selection.

To Select Part of a Selection:

Press Shift+Ctrl when you use a selection tool. An “x” symbol indicates that the area you select in the existing selection will remain selected. If none of the new selection is part of the existing selection, Canvas X Draw deselects all pixels.

You can also use Shift or Ctrl to constrain a selection when you add, subtract, or intersect a selection. To do this, press the keys to add, subtract, or intersect and begin dragging. While still pressing the mouse button, release the keys and then press the constraint keys and continue dragging.

See also:

• Working with Image Selections