Selection

Note: Photoshop tools and menus are used here as examples which may be different from other image editing programs.

Selection

Selection is used to protect an area outside the selection border. You can then perform many different tasks to only selected areas without affecting other parts of the image. You can move, copy, sharpen, adjust brightness and contrast, paint, or apply other effects to the isolated area. A selected area or marquee is indicated by a dotted border. There are different tools to make selections for bitmap and vector images, which are two different image data. Bitmap selection tools include the rectangle marquee tool, elliptical marquee tool, lasso tool, polygonal lasso tool, and magnetic lasso tool. Vector selection tools include the shape selection tool and the magic wand tool.

Selection tools

rectangle marquee tool
elliptical marquee tool
magic wand tool
lasso tool
polygonal lasso tool
magnetic lasso tool
shape selection tool

You can select an area of an image by dragging with the marquee tools or lasso tools, or by isolating color areas with the magic wand tool. You can also add or subtract from an existing selection. You use commands in the select menu to select all pixels, to deselect, or to reselect.

1- To select all pixels:

Select the active layer in the Layers palette.
Choose Select > All.

2- To deselect selections:

Choose Select > Deselect.

If you are using the rectangle marquee, elliptical marquee, or lasso tool, click anywhere in the image outside the selected area.

3- To reselect the most recent selection:

Choose Select > Reselect.

Marquee tools

The marquee tools draw rectangular and elliptical selection borders.

Select a marquee tool:

Rectangle marquee to make a rectangular selection.

Elliptical marquee to make an elliptical selection.

1- In the options bar, you can specify whether to create a new selection, add to a selection, subtract from a selection, or select an area intersected by other selections.
2- You can specify a feathering setting in the options bar. Feathering controls the sharpness of a selection’s edges. It produces a smooth transition between a selection and the surrounding area. A higher feathering value creates softer edges by feathering more pixels. Feathering is useful when pasting a selection. The fading helps the selection blend into the background and appear more natural.

3- Turn anti-aliasing on or off for the elliptical marquee. Antialiasing is similar to feathering, but more precise. It produces a smooth-edged selection by partially filling in pixels along the edge, making them semi-transparent. If antialiasing is not applied, the edges of a selection can appear jagged. Antialiasing is useful when combining images and when working with text.

Lasso, polygonal lasso, and magnetic lasso tools

The lasso and polygonal lasso tools let you draw both straight-edged and freehand selection border. With the magnetic lasso tool, the border snaps to the edges of areas in the image.

1- To use the lasso tool:

Select the lasso tool.
Drag to draw a freehand selection border.
To draw a straight-edged selection border, hold down Alt (Windows) or Option (Mac OS), and click where segments should begin and end. You can switch between drawing freehand and straight-edged segments.
To close the selection border, release the mouse without holding down Alt (Windows) or Option (Mac OS).

2- To use the polygonal lasso tool:

Select the polygonal lasso tool.
Click in the image to set the starting point.
To draw a straight segment, position the pointer where you want the first straight segment to end, and click. Continue clicking to set endpoints for subsequent segments.
To draw a freehand segment, hold down Alt (Windows) or Option (Mac OS), and drag. When finished, release Alt or Option and the mouse button.
To erase recently drawn straight segments, press the Delete key.

3- To close the selection border:

Position the polygonal lasso tool pointer over the starting point (a closed circle appears next to the pointer), and click.
If the pointer is not over the starting point, double-click the polygonal lasso tool pointer, or Ctrl-click (Windows) or Command-click (Mac OS).

4- To use the magnetic lasso tool:

Select the magnetic lasso tool.
Click in the image to set the first fastening point. Fastening points anchor the selection border in place.
To draw a freehand segment, move the pointer along the edge you want to trace. (You can also drag with the mouse button depressed.)

The most recent segment of the selection border remains active. As you move the pointer, the active segment snaps to the strongest edge in the image, based on the detection Width set in the options bar. Periodically, the magnetic lasso tool adds fastening points to the selection border to anchor previous segments.

If the border doesn't snap to the desired edge, click once to add a fastening point manually. Continue to trace the edge, and add fastening points as needed.

5- To switch temporarily to the other lasso tools:

To activate the lasso tool, hold down Alt (Windows) or Option (Mac OS), and drag with the mouse button depressed.
To activate the polygonal lasso tool, hold down Alt (Windows) or Option (Mac OS), and click.

5- To erase recently drawn segments and fastening points, press the Delete key until you've erased the fastening points for the desired segment.

6- Close the selection border:

To close the border with a freehand magnetic segment, double-click, press Enter or Return, or click anywhere outside the document window.
To close the border with a straight segment, hold down Alt (Windows) or Option (Mac OS), and double-click.
To close the border, drag back over the starting point and click.
To close the border, click anywhere outside the active window.

7- The lasso tool options let you customize how the different lasso tools detect and select edges.

To set options for the lasso tools:

Select the tool.
In the options bar, specify whether to create a new selection, add to an existing selection, subtract from a selection , or select an area intersected by other selections.

Specify feather and anti-aliasing options.

For the magnetic lasso tool, set any of these options:

To specify a detection width, enter a pixel value between 1 and 40 for Width. The magnetic lasso detects edges only within the specified distance from the pointer.

To specify the lasso's sensitivity to edges in the image, enter a value between 1% and 100% for Edge Contrast. A higher value detects only edges that contrast sharply with their surroundings; a lower value detects lower-contrast edges.

To specify the rate at which the lasso sets fastening points, enter a value between 0 and 100 for Frequency. A higher value anchors the selection border in place more quickly.

Note: While creating a selection, you can press ] to increase the magnetic lasso edge width by 1 pixel; press [ to decrease the width by 1 pixel.

The magic wand tool

The magic wand tool lets you select a colored area. It uses four types of values for making selections:· RGB value, hue, brightness, all opaque, and opacity. You specify the color range, or tolerance, for the magic wand tool's selection.

With RGB Value, it selects pixels based on the amount of Red, Green, and Blue.
With Hue, it selects pixels based on the position in the color wheel of the hues.
With Brightness, it selects pixels based on the amount of white they contain.
With All Opaque, it selects only areas containing pixels. No transparent areas are selected.
With Opacity, it selects pixels based on the opacity of the current pixel vs. the others.

To use the magic wand tool:

Select the magic wand tool
In the options bar, specify whether to create a new selection, add to an existing selection, subtract from a selection, or select an area intersected by other selections. The magic wand cursor changes depending on which option is selected.
For Tolerance, enter a range of pixel values, ranging from 0 to 255. Enter a low value to select colors very similar to the pixel you click, or enter a higher value to select a broader range of colors.
To define a smooth edge, select Anti-aliased.

To select only adjacent areas using the same colors, select Contiguous. Otherwise, all pixels using the same colors will be selected.

To select colors using data from all the visible layers, select Use All Layers. Otherwise, the magic wand tool selects colors from the active layer only.

In the image, click the color you want to select. If Contiguous is selected, all adjacent pixels within the tolerance range are selected.

Moving, hiding, or inverting a selection

At times, the easiest way to isolate an area is to select the part of the image you don’t want and then reverse the selection. For example, if you have an image where the background is one color and the foreground contains several colors, you can select the background and then invert the selection.

You can move a selection or hide a selection so the unselected part of the image is selected. Move tool

1- To move a selection border:

Using any selection tool, select new selection from the options bar, and position the pointer inside an existing selection border. The pointer changes to indicate that you can move the selection
Drag the border to enclose a different area of the image. You can drag a selection border partly beyond the canvas boundaries. When you drag it back, the original border reappears intact. You can also drag the selection border to another image window.

2- To control the movement of a selection:

To constrain the direction to multiples of 45° , begin dragging, and then hold down Shift as you continue to drag.

To move the selection in 1-pixel increments, use an arrow key.

To move the selection in 10-pixel increments, hold down Shift, and use an arrow key.

To select the unselected parts of an image:

Choose Select > Inverse.

3- The move tool lets you drag a selection or layer to a new location in the image.

Select the move tool
Move the pointer inside the selection border, and drag the selection to a new position. If you have selected multiple areas, all move as you drag.
Select the layer you want to move. Then drag the layer to a new position in the Layers palette.

4- To activate the move tool when another tool is selected, hold down Ctrl (Windows) or Command (Mac OS).

You can use the move tool to copy selections as you drag them within or between images, or you can copy and move selections using the Copy, Copy Merged, Cut, and Paste commands.

The Copy command copies the selected area on the active layer.

The Copy Merged command makes a merged copy of all the layers in the selected area.

The Paste command pastes a cut or copied selection into the center of the image or into another image as a new layer.

The Paste Into command pastes a cut or copied selection as a floating selection in the existing layer.

To copy a selection:

Select the area you want to copy.
Choose Edit > Copy to copy the selection to the Clipboard.

Choose Edit > Copy Merged to copy all layers in the selected area to the Clipboard.

To copy a selection while dragging:

Select the move tool, or hold down Ctrl (Windows) or Command (Mac OS)
Hold down Alt (Windows) or Option (Mac OS), and drag the selection you want to copy and move.

To paste one selection into another:

Cut or copy the part of the image you want to paste.
Select the part of the image into which you want to paste the selection as a floating selection. Note that the pasted image will only appear in the selected area. If you move the pasted image out of the selection, it is not visible.
Choose Edit > Paste Into.
Select the move tool, then drag the pasted image to the proper location.

Plug-ins

There are several third party software that can be installed under Photoshop, or all photo editing software that accept Photoshop compatible plug-ins. Two highly sophisticated programs are designed for making selections or masks. They are Extensis Mask Pro and Corel Knock Out. These programs make the job of masking much easier, faster, and more precise than the tools included in Photoshop and other high end software. I'll discuss Mask Pro here since this is a plug-in I use the most.

Mask Pro: Extensis Mask Pro is a powerful plug-in for Photoshop and other sophisticated editing software such as Corel Photo-Paint, Ulead PhotoImpact, and Jasc Paint Shop Pro. With Mask Pro you can create complex cutouts and selections for image composition, isolations, color corrections, and more. Innovative color controls produce superior masking results, and masking with Mask Pro is far easier than using conventional methods and tools. Mask Pro involves removing a narrow area all the way around the object to be masked, eliminating any stray pixels that might cause a leak or hole in the mask, then filling the rest of the area to be masked. Mask Pro provides you with some tools you're already familiar with (like the Brush, Bucket, Zoom and Hand tools) and also adds an array of specially developed Photoshop-like tools to make the masking process easy. Some of the features include:

EdgeBlender—Reduces or eliminates halos by replacing the color in partially transparent pixels along the edge of the mask, allowing masked images to blend better with new backgrounds.
PrecisionEdge Magic Pen Tool—Speeds normal Pen tool selections by automatically fitting path to the closest edge.
IntelliBrush and IntelliWand—Allows you to quickly start masking without selecting Keep and Drop colors. Simply click on the background and Mask Pro determines what to keep or drop—automatically!
Erase Only/Restore Only Mode—Allows you to erase or restore specific colors in your image.
Global Choke/Spread—User-definable choke/spread values allow you to tighten or loosen the entire mask.
Selection Filter—Gives you the option of creating a selection from your image, rather than dropping out the background.
Mask Pro Composite View—Lets you view your mask against background layers in the original image.
Full Stroke Undo—Enhances the already powerful incremental Undo/Redo by including a full-stroke undo, allowing you to undo an entire brush stroke at once.
Specify Background—Additional "view modes" let you view your masked image in QuickMask mode, or against a background color of your choice.
Apply to Entire Image—Adds the ability to apply tool functions to an entire image.
Revert—Lets you restore the original image prior to any masking that was done. Helpful when you want to start over from the beginning.
Clipping Path Generation—Ability to create clipping paths from selections as well as masks.
Clipping Path Proxy Preview—Visually indicates the effects of the Choke and Tolerance value settings before applying.
Tool and Palette Enhancements
Reset function restores all Palettes to a user-defined default.
(+) and (-) indicators added to tools to easily determine whether you're working in Erase or Restore mode.
Additional key commands to make tools, functions, and palettes easy to access.
Crosshair functionality for precise cursor positioning. Modified palette sliders now move independently.
Pen Tool now uses industry standard pen tool functions (exactly like Photoshop and Illustrator).
Hot Help gives you the name and functionality of tools and controls when the cursor is placed over them.

Masking Steps with Mask Pro

There are three different modes in which Mask Pro can be opened:

Mask mode, which allows you to drop out the background of an image;
Select mode, which allows you to create a selection and keep the background;
Mask Composite, which is just like Mask mode, but adds the ability to view all visible layers as you mask.

Which mode you choose determines which command you use to open Mask Pro. Commands for all three modes are available from the Extensis > Mask Pro menu in the Photoshop menu bar.

Open the Mask Pro plug-in by selecting the desired mode from the Extensis menu: Mask..., Select..., or Mask Composite...
Select colors to Keep and Drop—or allow Mask Pro to make the Keep/Drop color decisions automatically.
Select the areas to mask away using painting and drawing tools like the Magic Brush, Magic Wand, and Magic Pen
Search for holes and complete the mask using tools like the Bucket Fill and Magic Fill
Save the mask and return to Photoshop.

The Toolbox Palette gives you quick access to all the tools needed to create your mask and navigate the image. At the top of the palette are the Keep and Drop Eyedroppers, which allow you to select colors in the image to mask away (drop) and colors in the image to preserve (keep). A Mode indicator at the bottom of the Toolbox allows you to switch quickly between Erase mode, where you'll be painting away the background; Restore mode, where painting will restore pixels removed in Erase mode; and the special Dual Erase/Restore mode, which is available when you use the Magic Brush and Magic Fill tools. The remaining tools are painting and navigating tools that behave similarly to ones you're familiar with in Photoshop.

Special Keep and Drop Palettes organize the colors you select with the Keep and Drop Eyedropper tools.

Use the Keep and Drop Eyedroppers () to select colors from the image to retain or mask away. Drag through an area to create an "average" color to Keep or Drop. You can add colors and sets of colors, and activate and deactivate them as needed. You might want to create color sets for distinctly different areas of color, or when similarly colored areas appear in different places along the edge. You only need to choose a few Keep and Drop colors—Mask Pro works best with between one and four colors total, divided between the Keep and Drop Palettes. Keep and Drop colors affect only the Magic Brush, Magic Wand, and Magic Fill tools. You can use the Magic Brush, Magic Wand, and Magic Pen tools to make quick work of any masking task. These tools magically remove pixels that would otherwise be time consuming to remove.

Magic Brush: Use the Magic Brush tool to erase pixels along the edge of the image that you want to mask. To use the Magic Brush, select it from the Toolbox, then select Dual Erase/Restore mode (half black/half checkerboard in front). Paint along the edge that you want to erase. Mask Pro will analyze the active colors in the Keep and Drop palettes and will determine which areas to mask and which to keep based on those colors.

Use the Brush Size and Edge Palette to change brush size and softness. Use the Threshold setting on the Threshold Palette to vary how much of the image to keep. Pixels similar to the Keep colors stay opaque and pixels similar to the Drop colors become transparent. The Transition setting determines the softness of the edge that the Magic Brush (or Magic Wand or Magic Pen) will produce in response to a smooth transition between the Drop and Keep colors.

Magic Pen: Use the Magic Pen tool to draw a closed path around an area to mask either the area inside or outside of the path. To use the Magic Pen, select it from the Toolbox, then select Erase mode. Drag the pen along the edge that you want to erase-the line will snap to the edge. Drag out into the background and close the loop (), then click inside or outside the enclosed area () to remove those pixels.

Magic Wand: Use the Magic Wand tool to mask simple backgrounds consisting of just a few colors. To use the Magic Wand tool, select it from the Toolbox, then select Erase mode. Click in the area that you want to erase.

To mask around smooth edges, you might want to use the standard Brush or Pen tool. These tools do not utilize the Keep and Drop colors. When the mask is complete you'll want to apply it to your image. Select "Save/Apply" from the File menu. If you opened Mask Pro using either Mask... or Mask Composite..., Mask Pro will discard the background and return your mask to the selected channel. If you opened Mask Pro using Select..., Mask Pro will return your masked image as a selection.