[CREATE] Questions and reflections about gradients

[Sven Langkamp]

On Thu, Nov 4, 2010 at 12:19 AM, Olivier BERTEN <olivier.berten at gmail.com>wrote:

> Hi!
>
> Still going on with SwatchBooker, I'm now analysing gradients file
> formats <http://www.selapa.net/swatches/gradients/fileformats.php> and
> as I was thinking at my own format for these, there were some things
> triggering me... And I'd really like to have some other's opinions about
> them...
>
> * I don't see the point in Foreground/Background colors
> <http://www.mail-archive.com/create@lists.freedesktop.org/msg01272.html>
> ;-) I see even less the point in having gradients swatches defined with
> Foreground/Background colors... This is a "feature" you can find in
> Photoshop and Gimp gradients. For sure I don't see how it would be
> useful in an exchange format...
>

The feature itself makes sense (I recently added it to Krita on request).
That is mostly used for foreground-transparent and foreground-background
gradients that are handled by the applications internally but not exported.


> * In my idea, a gradient is defined by stops and the way to go from one
> to the other. All other things like shape, angle, center, etc. are how
> you use the gradient, not the gradient itself. Which means I would leave
> out these features when importing from OpenOffice.org or Flash.
>

Agreed.


> * I think the "segment" concept of Gimp isn't really interesting since
> the position of a segment start has to be the same as the end of the
> previous one, and in 99% of the cases, the color is the same too. For
> the 1% left, you can create another stop at the same position.
>

The main difference of the segmented gradients is that can have different
interpolations per segment. There are interpolations like sinus and color
interpolations like HSV. Of course in probably 99% of the cases just linear
is used. For the application it doesn't really matter if the gradient comes
as stop or segment gradient. In Krita we can use can use both types and for
Karbon we convert Gimp gradients to stop gradients (with potential loss of
some features).


> * I'm not sure yet how to deal with transparency. My first option would
> be to say: we're talking about color gradient and transparency isn't a
> color attribute, it's an object or painter attribute, so we leave it out
> completely. There's the Adobe's option to have a transparency gradient
> next to the color gradient but then again, why not really differentiate
> things and really separate them... But at least it would cover that
> feature because I really think including transparency into the color
> definition is wrong.
>

Transparency is at least needed for the stops, so it's linked to the stop
color anyway. The application can still decide if it wants to use the
transparency or not.


> * Is there any free software dealing with noise gradients?
>
> Even though I thought a lot about these things, I really appreciate
> contradiction so start shooting ;-)
>
> Olivier
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