Re: Tiff with mask
Re: Tiff with mask
- Subject: Re: Tiff with mask
- From: Isaiah <email@hidden>
- Date: Wed, 20 Feb 2002 07:47:27 -0800
You can save images as premultiplied TIFF files from Photoshop -- they just
use a different word for it (Save Image Pyramid).
1. Open the preferences->Saving Files dialog.
2. Click the "Enable advanced TIFF save options" checkbox and then click
OK.
3. Choose Save As... This will bring up the Save As... dialog.
4. Choose TIFF from the pop-up menu and click OK. This will bring up the
TIFF Options dialog.
5. Click "Save Image Pyramid" and then OK.
"Save Image Pyramid" is the same as premultiplying.
You might also want to "Save Transparency." This converts the transparency
of your Photoshop file into the correct Alpha channel -- so you don't have
to do that part by hand either.
Hope this helps,
Isaiah
on 2/18/02 2:41 PM, email@hidden at email@hidden said:
>
> Would someone explain premultiplication in this context. If I make a PS
>
> file with an alpha channel
>
> and save it as a tif I get the results I expect (used as icons in
>
> buttons for instance). Am I implicitly
>
> premultplying when I do this?
>
>
PS could save the TIFF premultiplied (but I believe PS does not do
>
that). So yes, you are implicitly premultiplying, on the load of your
>
image. You may be seeing a console log that is due to this, announcing
>
that your image has been premultiplied. The point of premultiplying
>
your images is largely to get rid of that log; the actual benefits in
>
terms of the performance of your app is pretty negligible (apart from
>
the overhead of the logging, which is probably significant :->). I wish
>
Apple would just take out the log and treat nonpremultiplied images as
>
"equal citizens", but so far they don't seem inclined to do that...
>
>
Ben Haller
>
Stick Software
>
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--
Isaiah
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