I'd like a tutorial on Gradiated (sp?) alpha channels.

[pixeltickler]

I'd like a tutorial on Gradiated (sp?) alpha channels, like the one Jim Johnston did for his Glamour puss retouch (#12). I know Jim gave a description of what he did, but I guess I'm either too dense or too inexperienced to make heads or tails of his directions. So is anyone out there up to making a tut on how to make that kind of alpha channel? OH and while I'm thinking of it. Maybe one on making masks/alpha channels when the background it is two-hued. All the tuts I've come across assume your background that you are masking off is all the same but what if it's not? What if it's both black and tan? Then what do you do?

Thanks in advance,
Diane

[roger_ele]

Hi,

I am replying for the opportunity to learn something and to show my ignorance ...

My understanding of all channels is that they are greyscale images. Red is a grey channel, blue and green also, for each layer. A layer mask is a grey channel attached to that layer only. Alpha channels are a storage device for those greyscale images that are not attached to anything. They can be used to create a selection and then create a mask from the selection, or in Apply Image or Calculations and I am sure in other ways ...

To create a gradiated Alpha mask i guess you would (I havn't done this before) create a layer or a mask, fill the layer or mask with a gradation with the gradation tool, Select the luminosity of that layer or that mask, save your selection as an alpha channel. Or maybe you can just create a new channel in the channels window and paint a gradation on the image???

If you had multiple colors the do different things you would need a channel for each seperateley if you wanted to affect the things they did seperately, or create a selection based on the combined colors and save that selection as an alpha channel.

I am sure I got part of this right, and for any I got wrong we will all learn double
Roger