W3C home > Mailing lists > Public > www-svg@w3.org > October 2010

Need to add <feColorRamp> to SVG

From: <kitfox@golden.net>
Date: Tue, 5 Oct 2010 09:30:27 -0400
Message-ID: <d3cd573085411c1319499aba247e9725.squirrel@www.webmail.execulink.com>
To: www-svg@w3.org
I'd like to propose adding an <feColorRamp> filter element to SVG.  This
is  a simple filter that takes selects a channel from an input image and
uses the intensity of a particular pixel to lookup a color value in a
gradient.

Reasons:

At the moment, the SVG filtering system provides ways to perturb images in
their domain (feDisplacementMap), but has only limited ability to remap
their range (feColorMatrix is probably the best existing option).  To use
fractal noise and turbulence to produce natural effects such as fire,
clouds, marble or wood, the intensity of the noise needs to be mapped to a
color ramp (gradient).  (See Ken Perlin's 'Making Noise'
http://www.noisemachine.com/talk1/)

Proposal:

A new filter element should be added to svg called <feColorRamp>.  It
would have the following attributes:

in: "SourceGraphic | SourceAlpha | BackgroundImage | BackgroundAlpha  |
FillPaint | StrokePaint | <filter-primitive-reference>"
	- Choose input image

channelSelector: "R | G | B | A"
	- Determines channel of input image that is remapped

ramp: <gradient>
	- The gradient that is used for remapping intensity values in the input
channel


Please let me know if you think this is a good idea, and where I should
submit this proposal if this list is not the best place.


Mark McKay


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Received on Tuesday, 5 October 2010 13:30:55 GMT

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