Friday, August 21, 2009

Adobe Lasso Tools


You can use the Lasso tool to make freeform selections by clicking and dragging. It is a useful tool for selecting irregular areas and for quickly adding to or subtracting from selections made with the Magic Wand tool.



Select the Lasso tool. Set Feather and Anti-aliased options. Position your cursor on the image. The cursor changes to the lasso cursor. Click and drag around the part of the image you want to select. Make sure your cursor comes back to the start point. If you release before reaching the start point. Photoshop completes the selection with a straight line. A dotted marquee defines the selected area.



Polygon Lasso Tool
The Polygon Lasso tool creates a freeform selection with straight line segments.


Select the Polygon Lasso tool. Position your cursor on the image, then click; move the cursor, then click …. And so on, until you have defined the area you want to select. Click back at the start point to completed the selection. Alternatively, you can double-click to close the selection marquee.

The Magnetic Lasso Tool
The Magnetic Lasso tool is most useful when you want to select an object or an area of the image which contrasts strongly with the area surrounding it.



1. Select the Magnetic Lasso tool. Click on the edge of the object you want to select to place the first fastening point. Either, move the cursor along the edge of the object, or click and drag along the edge to draw a freehand segment. as you move along the edge of the object, the ‘active’ segment of the selection border snaps to the most clearly defined edge in the image near the cursor. Fastering points are added automatically, at intervals, as you drag.

2. To close the selection border, position your cursor on the start point, (s small circle at the cursor indicates that you are on the start point) then click. Alternatively, double-click, or press the Enter/Return key. Photoshop creates a segment from the point you have reached to the start point of the selection border. To close the selection border with a straight line segment, hold down Alt and double-click.



Lasso Width

The Magnetic Lasso tool detects edges only within the specified distance from the pointer. Enter a value between 1-40.

Frequency

This setting determines the rate at which fasterning points are set. Enter a value between 0-100. The higher the value you set, the more frequently fastening points are placed.

Edge Contrast

Enter a value between 1-100%. This value determines how sensitive the Magnetic Lasso tool is tool is to edges in the image. Higher values select edges that contrast strongly with their background. Lower values select edges that have smaller amounts of contrast.



Hot Tip –
1. Hold down Shift, then click and drag around an area to add it to the selection. Hold down Alt, then click and drag around an area to remove it from the selection.
2. When you return to the start point with the Polygon Lasso tool, a small circle appears at the bottom right of the cursor to indicate that you can close the selection by clicking once.
3. Click on the edge of the shape if you need to add a fastening point manually.
4. If the object you are trying to select has high contrast (i.e., well defined edges) use higher Lasso Width and Edge Contrast settings. For objects with less well defined edges, use lower Lasso Width and Edge Contrast settings.
Beware –
If you have a feather amount set in the Lasso options Bar. You will not end up with sharp corners on the selection
Don’t Forget –
A fastening point anchors the Selection Border in place as you create the selection, fastening points disappear when you close the selection border. The Magnetic Lasso tool adds fastening points at intervals to the selection border to another the segments.

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