How 2, use the Alpha channels

[Mike Bailey]

Hi Folks, this little How 2 is for those who have never played with the alpha channels,

Think of it like this, You are an airbrush artist, you want to put a coating on your canvas that will protect it. Then you can remove areas of the coating where you want to put some paint. Alpha= a mask with any name you choose to put in place of alpha.

Channels, lets see..... its like watching TV, if you want to see something different you change channels. So if you want to use a different mask you switch to that alpha channel.

Using the channels gives you the capability to draw and edit a mask with pinpoint accuracy down to the pixel with any of Photo paints drawing tools, if you use grayscale on a mask it will have shading capabilities like a screen, you can apply filters and effects to them, you can use a single mask to create multiple copies of an object, if you import black and white or grey scale vector art into Photo paint you can use it to make a mask, you can make a bunch of them to use at your disposal over and over, you can save them to disk, etc..etc....


So to get started, open Photo paint. I'm using Photo paint 7 but it shouldn't matter

[This message was edited by Mike Bailey on March 08, 2002 at 04:01.]

[Mike Bailey]

Hi Folks, this little How 2 is for those who have never played with the alpha channels,

Think of it like this, You are an airbrush artist, you want to put a coating on your canvas that will protect it. Then you can remove areas of the coating where you want to put some paint. Alpha= a mask with any name you choose to put in place of alpha.

Channels, lets see..... its like watching TV, if you want to see something different you change channels. So if you want to use a different mask you switch to that alpha channel.

Using the channels gives you the capability to draw and edit a mask with pinpoint accuracy down to the pixel with any of Photo paints drawing tools, if you use grayscale on a mask it will have shading capabilities like a screen, you can apply filters and effects to them, you can use a single mask to create multiple copies of an object, if you import black and white or grey scale vector art into Photo paint you can use it to make a mask, you can make a bunch of them to use at your disposal over and over, you can save them to disk, etc..etc....


So to get started, open Photo paint. I'm using Photo paint 7 but it shouldn't matter

[This message was edited by Mike Bailey on March 08, 2002 at 04:01.]

[Mike Bailey]

Navigate as follows:
1.Open a new image,
2.Menu / Tools / Roll-up groups / Objects/Channels
(the Objects /Channels window opens) make sure the little thumb take is down so it will stay open.
3.CTRL+A or Menu / Mask / Select all
4.Objects/Channels roll-up/ Channels

You should see the channels in the roll-up like the image below, except you do not have an alpha channel yet. The first 4 or 5 depending on the color model you are using are the color channels, then you have the current mask channel, Ok the current mask channel is on because you selected all in step 3 and made a mask on your image, you must have a current mask channel to make an alpha channel which is a copy of the current mask. On the bottom of the Channels roll-up you will see 4 buttons,

Step 5 click the 2nd from the left button to save the current mask as a channel.

You will see a new alpha 1 channel on the list below the current mask channel, it will be outlined in red.

Ok, I need to explain a some stuff about this channel window so you will know how to navigate now that you have an alpha channel.
The first column of icons represent what is in the channel.

The second column that look like eyes represent what you see in the image window.

The third column has a pencil in the color model channel at the top of the list, this column is where you change from one channel to another as if you were changing channels on a TV, the channel you select with the pencil becomes visible by default and is editable.

So if at any time if you are experiencing problems check that the pencil is on the channel you wish to edit and that the eyes are on the channels you wish to view, if you switch back to the objects window the channels you have selected are what you get.

So now that you know all that, make as many alpha channels as you wish, I think there is a limit of 17 that you can have loaded at a time

[This message was edited by Mike Bailey on March 06, 2002 at 02:53.]

[Mike Bailey]

Ok you have an alpha channel and your ready to rock and roll now.

Get rid of the current mask with CTRL+D or click the remove mask button.
Put the pencil icon on the alpha channel, you will see that the image is white, all the eyes in column 2 are subdued except the alpha channel that you have turned on. The image is white because you have not coated it with your protective coating, get the fill tool and select black as the fill color and fill the image. The color Black level 0 is your protective coating. Any other shade of grey will let paint pass through the mask to some degree, white is no protection at all and paint will pass through full strength. Now click the Color model eye icon to view that channel at the same time as you are viewing and editing the alpha channel, notice that the black fill is now a shade of red, If there is an image on the color channel it will show thru your mask.

Grab the eraser and erase some of your mask, get the paint brush and paint some white paint on it. If you don't like what you have done, paint some black to cover it up. Use any tool you want. You can use the mask tools on it as well, apply some effects or filtering to see what happens.

When you are ready to use your alpha channel mask, if you have a mask on the current channel get rid of it. Then go to the bottom of the channels roll-up and click the left most button to make the alpha channel the current mask channel. Put the pencil back onto the color model channel (RGB or CMYK) turn off the eye icon on the alpha channel. Your new mask is now on your image ready for use. If you have several alpha channels the red border indicates which one is active and will be channeled onto the current mask channel. Only move the pencil icon onto a channel you want to edit, to select an alpha channel to use as a mask just click on the icon in the first column and the red border will move to that channel indicating that its active. Then you can channel it onto the current mask channel.

[This message was edited by Mike Bailey on March 06, 2002 at 03:16.]

[Mike Bailey]

[img]/infopop/emoticons/icon_cool.gif[/img]

[Mike Bailey]

[img]/infopop/emoticons/icon_smile.gif[/img]

[This message was edited by Mike Bailey on March 06, 2002 at 23:14.]

[Mike Bailey]

Example gray scale image used as a mask, this mask is from a poser model I worked on some time ago.

[This message was edited by Mike Bailey on March 06, 2002 at 23:21.]

[Mike Bailey]

Here's the image I made with the mask, Its mostly fills, I did a little editing but not to much.

I think I am done with this now.
Hope you get some use of it.

Best wishes to ya.