I found here an example:
http://blog.corunet.com/english/the-definitive-heatmap
it works, but it use external ImageMagick convert program

@opacity = "0.50"
@path = './'
transparency = "convert "<<@path<<'image.png -channel A -fx 
"A*'<<@opacity<<'"  '<<@path<<'image_transparent.png'
system(transparency)

How can I transform this in ruby rmagick code?


Chris Lowis wrote:
>> I use rmagick to create a new image.
>> How can I make this image with 50% transparency?
> 
> Take a look at the tutorials on the rmagick website ( 
> http://rmagick.rubyforge.org/ ). This one features transparency/opacity 
> :
> 
> http://rmagick.rubyforge.org/Polaroid/polaroid.html
> 
> I don't use rmagick very much, but I found these by googling "rmagick 
> transparent".
> 
> Hope this helps,
> 
> Chris

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