Sunday, October 17, 2010

Marquees Based selection

The most basic way of making a selection in photoshop is to use one of the standard shaped marquees. The standard shapes are: elliptical and rectangular.

There are also two marquees that select either horizontal or vertical rows that are one pixel wide. These are useful for drawing one pixel wide lines and creating 'pixel stretch' effects. See ourpixel stretch tutorial here.

In this tutorial we will be selecting the wheel of a car using the marquee tool.

Note that to remove a selection after it is no longer required (or in order to make a new selection) use the 'deselect' option on the 'select' menu [ ctrl - D ] . Also on the 'select' menu you can use the 'inverse' option to select the inverse of the current selection.


Choose the elliptical marquee from the top left of the toolbar. You may have to click and hold the tool to bring up the menu of marquee tools.



Once the elliptical marquee tool is selected draw an oval selection over the wheel. The easiest way to do this is to hold down the [ Alt ] key after you have started drawing (this will enable you to begin drawing from the centre of the wheel rather than from the top left). Another good tip is to hold down the spacebar while you are holding down the left mouse button. This will enable you to draw and move the selection at the same time.



Having selected the wheel of the car you will want to do something with the selected area. To copy or move it to a new layer, simply select 'New' from the 'Layer' menu and choose either 'Layer via copy' [ ctrl - J ] or 'Layer via cut' [ shift - ctrl - J ]. Thus the selected area of the image will be copied/cut onto a new layer.

Once you have made a selection you can create another selection that subtracts from the original.



Once you have selected the wheel you can remove the centre of the wheel from the selection. Just hold down [ Alt ] while selecting the wheel's centre.



You can also add areas to the original selection. Hold down [ shift ] while selecting the top ring of the Audi logo.



When you have finished adding/removing areas from the original selection you can move the defined area to a new layer or simply shift the selection to a new area on the same layer. To move the selection to a location on the same layer just hold down [ ctrl ] while dragging the selected area. To copy the selection to somewhere on the same layer hold down [ alt ] while dragging the selected area. If you do not hold down [ ctrl ] or [ alt ] you will simply move the location of the selection.

Having made a selection it is possible to create another selection that intersects the original by holding down both the [ alt ] and [ shift ] keys at the same time while drawing the second selection.



Start by selecting the wheel with the elliptical marquee tool. Then hold down the [ alt ] and [ shift ] keys together while drawing a rectangular marquee ( you will need to switch to the rectangular marquee tool) that intersects the original selection. Note: intersection is the default behaviour after a selection has been made, thus holding down [ alt ] and [ shift ] together is optional.


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