[magick-users] How to change the color of an transparent png

[Anthony Thyssen]

froesi on  wrote...
| Hi guys,
| 
| I've a vector graphic with a single color as an png file.
|
That is not posible,

It is posible to have a vector graphic RENDERED as a PNG image file.

| To look smooth the graphic has  an anti aliasement.  I tried something
| like this
| 
| -fuzz 4 % -fill "#FFFFFF" -opaque "#000000", but the thing is, that
| not every pixel of the graphic will be conerted to the new color.  I
| need something like this
| 
| http://www.lsus.edu/sc/math/rmabry/imagemagick/multireplace
| ->>"Replace black with blue #0000ff:"
| 
| I've no idea how to get this. It would be really great, if someone can
| give me a hint.  Thank you,
| 
If the document only has a gradient of two colors and no other colors
involved.  Then the solution is simple, if not then you need something
like multi-replace.

First convert the image to greyscale, and normalize it to maximised the color
gradient.  Do not use -normalize as it has some clipping add for handling
JPEG images....

   -colorspace gray -contrast-stretch 0

See
   http://imagemagick.org/Usage/color/#grayscale
   http://imagemagick.org/Usage/color/#contrast-stretch

You could also extract a color channel, and normalize (stretch) that
image...
   http://imagemagick.org/Usage/channels/#separate

now use either color gradient replacement or a mathematically
re-coloring method.  Lots of these are shown in IM examples, Color
Modifications
    http://imagemagick.org/Usage/color/

Alturnativally have two images of the colors (or pattern) wanted for
each end of the gradient, and use the normalized image as a mask
using a three image composite...
   http://imagemagick.org/Usage/compose/#mask


  Anthony Thyssen ( System Programmer )    <A.Thyssen at griffith.edu.au>
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   "Oh, the pain... the pain of it all!"  -- Doctor Smith, Lost in Space
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     Anthony's Home is his Castle     http://www.cit.gu.edu.au/~anthony/