Selecting (General)

Q1:	How can I adjust or alter a selection?
A1:	When using any selection tool with an existing selection, hold down Shift to add to the selection or press-and-hold Option (PC: Alt) to remove from the selection. From the Select menu, choose Similar, Grow, or choose Modify to Contract, Expand, etc. In Quick Mask mode (Q), paint with black to deselect (mask) and white to select. Use Transform Selection from the Select menu. * Remember, don't be afraid to switch between selection tools.
Q2:	How do I create an accurate circular selection? I'm trying to create a circular selection using the Elliptical Marquee, but I find it very difficult to know where to start dragging to get an accurate selection. Any hints?
A2:	With the Elliptical Marquee, make a circular selection of any size . Then from the Select menu, choose Transform Selection. This command will add "handles" that will let you resize the selection as much as you like. When you're happy, press Return (PC: Enter). ( Note: Do not use Free Transform because that command actually alters the pixels, whereas Transform Selection alters only the selection.) If you need to make a circular selection to a specific size, in the Options Bar, change the Style pop-up menu to Fixed Size and enter the sizes you need in the Width and Height fields. Then click-and-hold with the Marquee tool and drag to position the selection.
Q3:	How do I select the opposite of what I have selected?
A3:	From the Select menu choose Inverse, or press Command-Shift-I (PC: Control-Shift-I).
Q4:	How can I make a selection bigger? I've made a Marquee selection, but it's a little too small. Can I resize it, or do I have to start again?
A4:	You can use a function called Transform Selection (from the Select menu). This will add "handles" to a selection (made with any selection tool) that allow you to resize and rotate the existing selection. Press Return (PC: Enter) to finalize the transformation or Escape to cancel.
Q5:	What are the icons in the Options Bar for? The selection tools all have the same icons at the beginning of the Options Bar. What are those for?
A5:	The icons change the behavior of the selection tool: New Selection, Add to Selection, Subtract From Selection, or Intersect With Selection (meaning you want to select an area intersected by other selections). Choose one of the icons before you use the tool (and remember, this setting will now be the default until you change it).
Q6:	How can I make a selection slightly smaller?
A6:	From the Select menu, choose Modify> Contract and enter a number to make your selection that many pixels smaller.
Q7:	How can I make a selection slightly larger?
A7:	From the Select menu, choose Modify>Expand and enter a number to make your selection that many pixels larger.
Q8:	What is Quick Mask?
A8:	Quick Mask is a different way of viewing and working with a selection. After making a selection, click on the Quick Mask icon near the bottom of the Toolbox (or press Q) and the selection edges will be " replaced " with a colored overlay. The colored areas represent the areas that are not currently selected; the transparent areas represent the selection. To fine-tune the selection in Quick Mask, use the Brush tool (B) and paint with black to remove areas from the selection, or paint with white to add to the selection (you can toggle between the two colors by pressing X). To return to Standard viewing mode, press Q again.
Q9:	What is an Alpha channel?
A9:	Every document is made up of channelsa Grayscale image has one (Gray), RGB has four (RGB, Red, Green, and Blue), CMYK has five (CMYK, Cyan, Magenta, Yellow, and Black). Alpha channels are channels that are created in addition to these existing channels. Alpha channels contain grayscale information that is used for a number of purposes, most often to "store" selection information. For example, if you make a complex selection and want to use it again, use a command called Save Selection (from the Select menu). That will create an Alpha channel filled with white (where the selection is) and black (everywhere else). When the channel is loaded back into the image (Select>Load Selection), the black areas are ignored and the white areas are selected. Note: Alpha channels add to your file size, so you may want to delete extra Alpha channels once they've served their purpose.
Q10:	Why do I have so many Alpha channels? I had created an Alpha channel, and then thought I was updating it, but now I have a whole bunch of Alpha channels. How come?
A10:	Whenever you choose Select>Save Selection, the default in the Save Selection dialog is to make a new channel. So each time you chose Save Selection, you were creating a new Alpha channel. Instead, when you choose Save Selection, go to the Channel pop-up menu and choose your existing Alpha channel, rather than letting it create a new one each time.
Q11:	Is it possible to work with Alpha channels in the same way as Quick Mask? I like the way Quick Mask uses the colored overlay to work with selections. Is there a way to have Alpha channels display that way?
A11:	Yes, you can work with Alpha channels using the same kind of overlay as Quick Mask. In the Channels palette (Window>Channels), choose the Alpha channel you want to work with, then click on the Eye icon beside the RGB channel. The Alpha channel and the RGB channel will display (and work) just like Quick Mask.