INSTRUCTOR: xtine ...AIM Screen Name: hereisxtine

DAY/TIME: Wednesday 12:45 - 5pm

OFFICE HOURS: Tuesday 3:30 - 5:30

Home

Syllabus

Assignments

Links

10/12/05

This week we critiqued the DADA montages and then we completed chapter 6 on using Quick Mask and creating Alpha Channels.

Alpha Channels and QuickMask

Use QuickMask to create a selection with a paintbrush. The advantage is that you can get a soft edge around your selection--it is great for creating a selection on an image that you will want to blend with other images.

*Tip: create a quick selection, even if it is tiny, before entering QuickMask. I usually use the Magic Wand first.

Enter QuickMask by hitting the icon for QuickMask at the bottom of your tool palette (directly underneath the color chips), or press the letter Q on your keyboard.

All masks are editable with black, white and shades of gray loaded on your paintbrush (or

other drawing tool). Now, I always get this wrong:) but black paint on a mask will add to the mask and hide the image while white paint on a mask will subtract from the mask and show the image. When I paint on a mask I just click once with whatever is in the foreground color chip (it's always either black or white) and if it's not what I want, I hit X on the keypad and correct my mistake.

You can get out of QuickMask mode at any time by clicking on the icon next to QuickMask (lower left under the color chips) or by hitting the letter Q on your keypad (again). Q Q Q Q - into QuickMask, out of QuickMask, into QuickMask, out of QuickMask...get it?

It's a good idea to go in and out of QuickMask while you are working so that you can see what the selection edges are looking like.

Once you are done creating the selection, exit QuickMask and save the selection.

Saving Selections

If you spent a long time making the perfect selection and then your computer crashed, you will have lost that selection unless you bothered to save it. Selections are only saved when you save the selection--and then save the file.

There are a few ways to save a selection. You can choose Select Menu: Save Selection, name the selection and then hit OK. Alternatively, you can look in the Channel palette and click the icon at the bottom left of the palette for "Save selection as Channel". Once a selection is saved, it is always stored in the Channel palette.

Alpha Channels

All saved selections are called "Alpha Channels". Alpha channels are not only used in the medium of print, but also in video and animation. They are very important to the multimedia industry! Alpha channels are black, white and gray.

The Channel Palette

In your channel palette, if you want to correct an alpha channel (add to it by painting with

white or black) you can load just the alpha channel by clicking on its name. Always select an alpha channel by clicking on its name and NOT on its eyeball. Whatever you do, avoid clicking the eyeballs in the Channel palette. To get back to "normal" or standard editing mode, click the word: "RGB" in the channel palette. Clicking on

RGB in the channel palette selects the RGB composite channels (meaning that the RGB channel, the red channel, the green channel, and the blue channel are all highlighted and all of their eyeballs are on AND no other eyeballs are on AND no other alpha channels are highlighted).

Hot Keys:

Q Enter and Exit QuickMask

D Sets default foreground/background color chips

to black/white

X Switches the foreground and background colors

B Selects the paintbrush

[   Selects a smaller brush size

]   Selects a larger brush size

command+ C: copy

command + V: paste

command + Shift + V: paste into

command-click on an alpha channel (on the name,

not the eyeball): loads a selection

command-click on a layer: loads a selection of

everything on that layer