[PD] [GEM] Problem with alpha masks

[Daniel Heckenberg]

Hi,

On 14/5/03 10:25 AM, "arm pdlist" <arm_pdlist at yahoo.co.uk> wrote:

> Anyone, please?
> 
> --- arm pdlist <arm_pdlist at yahoo.co.uk> wrote: > I've
> been trying to do some alpha masks with the
>> "alpha" object and some images and videos. I have
>> two
>> images where all the black is ignored and the other
>> colors appear (just like i wanted). But around the
>> edges of a pic where i have black and some other
>> color, there is some "noise" in the mask...

I understand the problem.

>> Do you know how i can eliminate or minimize this
>> "noise"? I've tried "pix_mask", but since in this
>> project i use video too, my system crashes (i'm
>> using
>> xin xp). Is there any way to resolve this?

I'll try to fix the pix_mask crash, but I don't think that will solve this
problem.

You need to ensure that the alpha channel of your image mask is feathered at
the edges: it's not just 0 or 1 but has a smooth transition at the mask
edges.  By far the easiest way to do this for static images is to use an
image editor that can feather in the alpha channel and save the image with
alpha.  

I believe that JPEGs can store alpha, but you're likely to get some
chunkiness in the feathering unless you use quite high quality levels.
Otherwise you can use TIFF of course.

Daniel