Selections are a big deal in Adobe Photoshop. If your boss says to you, "Can we cut out this person and put them against a different background?", there is no way that you can tell the program to do this. As far as a computer is concerned, your image is just a series of pixels. How easy or difficult it is to select the person will depend on how much contrast there is between them (or more likely their clothes) and the background scene behind them.
It is often the case that, having made a selection, you will often need to transform it in some way. Photoshop selections can be transformed in a manner not dissimilar to the way that objects are transformed in the vector environment. One key thing to remember is that in order for this transformation to work, one of the selection tools has to be active. If the Move tool is active, the pixels inside the selection will also be transformed.
Moving a selection is probably the simplest form of transformation. This can be done either by placing the cursor inside the selection and dragging or by using one of the cursor keys on the keyboard. Each time a cursor key is pressed, the selection will move one pixel in the direction specified. If the Shift key is held down while a cursor key is pressed, the selection will move 10 pixels in the given direction.
To resize and rotate a selection, choose Transform Selection from the Select menu. A bounding rectangle will then be displayed around the selection with handles similar to those found in vector drawing programs. You can drag the handles to resize the selection or drag just outside the handles to rotate. You can even hold down the Control key and drag the handles to distort your selection.
As well as transforming a selection by manipulating it, Photoshop's Select menu also contains a number of automatic transformation commands. One of the most commonly used is feathering: Select - Feather. Feathering blurs the edges of a selection enabling the selected area to blend into the non-selected parts of the image. To access the other options go to the Select - Modify sub-menu. For example, the command Select-Modify-Expand allows you to increase the size of the selection by the number of pixels you specify. Naturally, there is also the reverse command: Select-Modify-Contract.
It is often the case that, having made a selection, you will often need to transform it in some way. Photoshop selections can be transformed in a manner not dissimilar to the way that objects are transformed in the vector environment. One key thing to remember is that in order for this transformation to work, one of the selection tools has to be active. If the Move tool is active, the pixels inside the selection will also be transformed.
Moving a selection is probably the simplest form of transformation. This can be done either by placing the cursor inside the selection and dragging or by using one of the cursor keys on the keyboard. Each time a cursor key is pressed, the selection will move one pixel in the direction specified. If the Shift key is held down while a cursor key is pressed, the selection will move 10 pixels in the given direction.
To resize and rotate a selection, choose Transform Selection from the Select menu. A bounding rectangle will then be displayed around the selection with handles similar to those found in vector drawing programs. You can drag the handles to resize the selection or drag just outside the handles to rotate. You can even hold down the Control key and drag the handles to distort your selection.
As well as transforming a selection by manipulating it, Photoshop's Select menu also contains a number of automatic transformation commands. One of the most commonly used is feathering: Select - Feather. Feathering blurs the edges of a selection enabling the selected area to blend into the non-selected parts of the image. To access the other options go to the Select - Modify sub-menu. For example, the command Select-Modify-Expand allows you to increase the size of the selection by the number of pixels you specify. Naturally, there is also the reverse command: Select-Modify-Contract.
About the Author:
The author is a training consultant with a UK IT training company offering Adobe Photoshop classes as well as Adobe Acrobat training at their central London training centre.
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