Generating Color Palette Using ColdFusion & ImageMagick

I read Ben Nadel's recent ColdFusion post on Exploring Color Histograms In GraphicsMagick And Lucee CFML 5.2.9.31 and thought I'd compare it with ImageMagick.

ImageMagick returns a list of color data in a low-to-high order. I used ReMatch to identify the hex colors via regex, generated an array and then reversed it.

NOTE: I wanted to compare performance using Ben's script, but his "Lucee CFML" script wasn't written to be compatible with ColdFusion 2016. :(

Usage

colors = extractPalette(imagePath, numberOfColors);

Source Code

	<!--- 20200311 Extract Color Palette using ColdFusion and ImageMagick
	USAGE: extractPalette(filepath, numberOfColors)
	GIST: https://gist.github.com/JamoCA/d2814588b6f518c72713becb3625c5bb
	BLOG: https://dev.to/gamesover/generating-color-palette-using-coldfusion-imagemagick-25bp
	--->
	<cffunction name="extractPalette" returntype="array" output="no">
	<cfargument name="filepath" type="string" required="true">
	<cfargument name="numberOfColors" type="numeric" default="5" required="true">
	<cfargument name="EXEpath" default="c:\ImageMagick\convert.exe" type="string" required="true">
	<cfset var Temp = {raw="", response=[]}>
	<cfexecute name="#arguments.EXEpath#" arguments="#arguments.filepath# -resize 300x +dither -colors #VAL(Arguments.numberOfColors)# -define histogram:unique-colors=true -format ""%c"" histogram:info:" variable="Temp.Raw" timeout="5"></cfexecute>
	<cfscript>
	Temp.Colors = ReMatch("##([A-Fa-f0-9]{6}|[A-Fa-f0-9]{3})", Temp.Raw);
	for (Temp.color in Temp.Colors){
	for (temp.i=ArrayLen(Temp.Colors); temp.i GT 0; temp.i=temp.i-1){
	if (arrayLen(temp.response) GTE arguments.numberOfColors){break;}
	arrayAppend(temp.response, Temp.Colors[temp.i]);
	}
	}
	</cfscript>
	<cfreturn Temp.response>
	</cffunction>
	<cfset timeStart = GetTickCount()>
	<cfset Colors = extractPalette(imagePath, 5)>
	<cfoutput>
	<div><b>Time:</b> #NumberFormat(GetTickCount()-TimeStart)#ms</div>
	<cfloop array="#Colors#" index="thisColor">
	<div><span style="background-color:#ThisColor#; min-width:50px; display:inline-block;">&nbsp;</span> #thisColor#</div>
	</cfloop>
	</cfoutput>

view raw extractPalette.cfm hosted with ❤ by GitHub

Comments

[Ben Nadel]

I came across some similar things in various ImageMagick forums when I was looking into this. I wonder if the -define histogram:unique-colors=true is part of why I am not getting results that I love. GraphicsMagick doesn't seem to have an equivalent setting.

On various color palette posts, I did see that some people were calculating the "distance" between colors to help figure out a palette. But, I am not so good at maths ... or understanding color theory :D Part of me is like, let me just show the top 30 colors and let the user pick out whatever they like.