Expert: LizaL - 6/22/2005

Question
-------------------------
Followup To
Question -
I am an artist.  I am using Photoshop CS for creating digital art and
illustrations.
I want to use the Alpha Channel (into which I have added a radial
gradient) to darken (shadow effect) a part of the background.  
There is a light source (fire) that I have painted in and I need the
extra "shadow" to create more perspective.
How do I use the Alpha Channel to do this?
Answer -
Hi Jennifer,

I would suggest using Curves to adjust the shadows area of your
gradient. In your channels
palette, select your alpha channel, and just use Curves as you normally
would on any layer.
Curves is the best way I know to add shadow to any image, regardless
of whether it's in a color
layer, or an alpha channel.

I created a test gradient in an alpha shadow and adjusted it with
Curves to show you what I
mean:
http://little-works.com/all_experts/alpha_test.mov

What I did was create the alpha channel, add a gradient, then I used
Curves to bring up the
darkest area of the gradient. The gradient, BTW, is a red-to-yellow one
I created. At the end of
the little movie I'm turning on and off the alpha channel to show you
the difference.

But the best way for me to understand if this is what you need is for
me to actually see your
image.

We can go about this two ways, either email or uploading. If you have a
place for uploading files,
could you upload this file for me to download and look at?

Or -- can you send me your image, and let me take a look at it? I'll give
you two email addresses
for this:
lizal@little-works.com

lizal_ae@hotmail.com

That said, my Web host is having trouble with the email account on the
first address, and if I
don't answer fairly soon, you'll know I didn't receive your mail. But if
the file isn't huge, HotMail
can probably handle it.

Hope this helps, and if not, please either post back and provide a little
more description as to
what you're doing, send me your file, or post your file where I can
download it.

Thanks!

Lisa

Lisa,

Thank you for trying to offer assistance, but I have researched the
Adobe site and found the
information I was looking for.

You failed to address using the Alpha Channel in your response. I
looked at your example. First,
you ignored the fact that I used a "radial gradient", second you simply
"changed the channel
characteristics already present - you did not "load a new channel into a
layer", background or
otherwise.

You did tell me about Curves (a correction tool for customized,
accurate image corrections by
applying mathematical input to adjust everything from contrast/
brightness to color balance etc.).  
Understanding and using the Curves adjustment is "fundamental
Photoshop" technique.  

You should be aware that your use of Curves in your demo is amateur
- Curves should be
adjusted with one or many "reference points" and maintain either a
concave or convex form. Your curve adjustment pulls down in the
selection, then flattens out - creating an input variable
of 89 and an output value of 0 - this is not a good example of using
Curves.

I wanted to know how to load the Alpha Channel I had already created
(and corrected for my
image) into my background layer/s. I discovered that I simply load the
channel into the
background layer and use the transparency slider to adjust it for the
amount of shadow/darkness
I desired.  I learned that I did not need to make an additonal layer or
use the "multiply" option to
allow the Alpha Gradient to become effective.

I visited your websites; your page layout skills are good.  Your
knowledge of Photoshop does not
appear to reach beyond the basics.

Thank you for your effort.
Jennifer  

Answer
Jennifer,

In my career, it's been seldom, fortunately, that I have run across those people who are so insecure that they can only criticize the knowledge and expertise of others. I would presume that you fall into that category, having taken the opportunity to try and demean me in a benign public forum such as All Experts.

Your overall criticism does not bother me; nor does it bother me that you choose to critique and comment on my advice or my work (i.e., my Web site). Believe me, you are not the first, nor will you be the last, to have an opinion. I've been a designer for many years, and have had no shortage of critiques.

I'm glad you found the answers you need. That, to me, is the ultimate goal of any good teacher.

However, from one artist to another, you should be able to understand that I can in no way determine what your Photoshop needs are from the short text description you first sent me. I offered you two email addresses to which you could send your files so that I could inspect them and offer concrete advice, but apparently you didn't see the need to take me up on my offer.

Good luck to you in your artistic endeavors.

Lisa