# Imagemagick, Rmagick hsla problem **URL:** \ **Category:** Ruby\ **Created:** [August 9, 2009, 5:35pm UTC](https://www.ruby-forum.com/t/imagemagick-rmagick-hsla-problem/173455 "2009-08-09T17:35:20Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![vtphysguy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/77aa72/32.png) [@vtphysguy](https://www.ruby-forum.com/u/vtphysguy)\ **Post date:** [August 9, 2009, 5:35pm UTC](https://www.ruby-forum.com/t/imagemagick-rmagick-hsla-problem/173455/1 "2009-08-09T17:35:20Z")
For any imagemagick users out there, I’m having trouble getting Rmagick’s hsl functions to work for me. I use the following code: @canvas.background\_color = Magick::Pixel.from\_hsla(80, 100, 50, 1) To try and set a HSLA background color for my image, but it keeps coming out white. Any idea why? The image is made okay, no errors are thrown in the ruby code. Ruby version: 1.8.6 ImageMagick Version: 6.5.3 Q8 Rmagick Version: rmagick-2.10.0-x86-mswin32 OS: Windows Vista ---
**Author:** ![vtphysguy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/77aa72/32.png) [@vtphysguy](https://www.ruby-forum.com/u/vtphysguy)\ **Post date:** [August 9, 2009, 5:50pm UTC](https://www.ruby-forum.com/t/imagemagick-rmagick-hsla-problem/173455/2 "2009-08-09T17:50:40Z")
Justin Bl wrote: > Ruby version: 1.8.6 > ImageMagick Version: 6.5.3 Q8 > Rmagick Version: rmagick-2.10.0-x86-mswin32 > OS: Windows Vista I don’t think the problem is with the from\_hsla method. This produces a nice sorta lime-green 200x200 image for me. Why don’t you post a complete script that reproduces the problem? irb(main):001:0\> p = Magick::Pixel.from\_hsla(80, 100, 50, 1) =\> red=170, green=255, blue=0, opacity=0 irb(main):002:0\> img = Magick::Image.new(200,200) { self.background\_color = p} =\> 200x200 DirectClass 8-bit irb(main):003:0\> img.display =\> 200x200 DirectClass 8-bit ---
**Author:** ![vtphysguy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/77aa72/32.png) [@vtphysguy](https://www.ruby-forum.com/u/vtphysguy)\ **Post date:** [August 9, 2009, 6:12pm UTC](https://www.ruby-forum.com/t/imagemagick-rmagick-hsla-problem/173455/3 "2009-08-09T18:12:14Z")
Tim H. wrote: > Justin Bl wrote: > > > Ruby version: 1.8.6 > > ImageMagick Version: 6.5.3 Q8 > > Rmagick Version: rmagick-2.10.0-x86-mswin32 > > OS: Windows Vista > > I don’t think the problem is with the from\_hsla method. This produces a > nice sorta lime-green 200x200 image for me. Why don’t you post a > complete script that reproduces the problem? > > irb(main):001:0\> p = Magick::Pixel.from\_hsla(80, 100, 50, 1) > =\> red=170, green=255, blue=0, opacity=0 > irb(main):002:0\> img = Magick::Image.new(200,200) { > self.background\_color = p} > =\> 200x200 DirectClass 8-bit > irb(main):003:0\> img.display > =\> 200x200 DirectClass 8-bit Tim, Full source code is below: require ‘rubygems’ require ‘rvg/rvg’ include Magick class MyImage def initialize (job\_id, width, height) @job\_id = job\_id.to\_s; @width = width.to\_i; @height = height.to\_i; @canvas = Magick::Image.new(@width, @height) #@canvas.colorspace = HSLColorspace @canvas.background\_color = Magick::Pixel.from\_hsla(80, 100, 50, 1) #it will make the pixel but it will not make it the right color end def draw () # choose random color and put it in a pixel #@canvas.each\_pixel {|pixel, c, r| #ind = rand(5) #pixel = $colors[ind] #} #@canvas.pixel\_color(x, y[, new\_color]) -\> pixel end def finalize (type=“gif”) @canvas.write("#{@job\_id}.#{type}") end end x = 500 y = 500 increm = 360/5 $colors = Array.new $colors = [ [0,100,50,1], [72,100,50,1], [144,100,50,1], [216,100,50,1], [288,100,50,1] ] # initial array is just the h s l a values $colors = $colors.map { |xx| Magick::Pixel.from\_hsla(xx[0], xx[1], xx[2], x[3]) } # convert it to array of pixels puts $colors[0].class img = MyImage.new(“hsl\_test”, x, y) img.draw() img.finalize(‘png’) ---
**Author:** ![vtphysguy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/77aa72/32.png) [@vtphysguy](https://www.ruby-forum.com/u/vtphysguy)\ **Post date:** [August 9, 2009, 6:19pm UTC](https://www.ruby-forum.com/t/imagemagick-rmagick-hsla-problem/173455/4 "2009-08-09T18:19:56Z")
Justin Bl wrote: > > irb(main):001:0\> p = Magick::Pixel.from\_hsla(80, 100, 50, 1) > > require ‘rubygems’ > > #@canvas.colorspace = HSLColorspace > > $colors = Array.new > > # convert it to array of pixels > > puts $colors[0].class > > img = MyImage.new(“hsl\_test”, x, y) > img.draw() > img.finalize(‘png’) The color of a new image is set when the image is created. Do this: @canvas = Magick::Image.new(@width, @height) do self.background\_color = Magick::Pixel.from\_hsla(80, 100, 50, 1) end Setting the background\_color attribute _after_ creating the image only changes the value of the background\_color attribute. It doesn’t actually change the color of the image. ---
**Author:** ![vtphysguy](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/v/77aa72/32.png) [@vtphysguy](https://www.ruby-forum.com/u/vtphysguy)\ **Post date:** [August 9, 2009, 6:40pm UTC](https://www.ruby-forum.com/t/imagemagick-rmagick-hsla-problem/173455/5 "2009-08-09T18:40:11Z")
Tim, Thanks very much for your help. The code you posted works. Tim H. wrote: > Justin Bl wrote: > > > > irb(main):001:0\> p = Magick::Pixel.from\_hsla(80, 100, 50, 1) > > > require ‘rubygems’ > > > #@canvas.colorspace = HSLColorspace > > > > $colors = Array.new > > > > # convert it to array of pixels > > > > puts $colors[0].class > > > > img = MyImage.new(“hsl\_test”, x, y) > > img.draw() > > img.finalize(‘png’) > > The color of a new image is set when the image is created. Do this: > > @canvas = Magick::Image.new(@width, @height) do > self.background\_color = Magick::Pixel.from\_hsla(80, 100, 50, 1) > end > > Setting the background\_color attribute _after_ creating the image only > changes the value of the background\_color attribute. It doesn’t actually > change the color of the image.