Snippet and Theme Settings to for converting a Shopify CDN image path into an Imgix path. Snippet allows for the passing of Imgix filters.

imgix-theme-settings.json

{
    "name": "Imgix",
    "settings": [
      {
        "type": "paragraph",
        "content": "For more info on these theme settings refer to the original [blog post](http:\/\/freakdesign.com.au\/blogs\/news\/91099207)"
      },
      {
        "type": "checkbox",
        "id": "enableImgix",
        "label": "Enable Imgix",
        "info":"Toggle the imgix feature"
      },
      {
        "type": "text",
        "id": "imgixUrl",
        "label": "Imgix Subdomain",
        "info":"The subdomain you set within Imgix. eg: '//foo.imgix.net'."
      },
      {
        "type": "text",
        "id": "imgixShopifyUrl",
        "label": "Shopify CDN domain",
        "default":"//cdn.shopify.com",
        "info":"No changes should be need here unless you have a proxy in place. Not sure? Leave as is."
      }
    ]
  }

imgix.liquid

{% capture IMGIX %}
{% comment %}
<!--

 _                 _
(_)_ __ ___   __ _(_)_  __
| | '_ ` _ \ / _` | \ \/ /
| | | | | | | (_| | |>  <
|_|_| |_| |_|\__, |_/_/\_\
             |___/

Convert a Shopify CDN path into an Imgix path, with fiters.
Snippet by Jason @ freakdesign.

###########################################

Usage:
{% assign productImage = product | img_url: 'grande' %}
<img src="{% include 'imgix' src:productImage gam:100 con:23 shad:-100 %}" />

Refer to the original blog post for more info about this:
http://freakdesign.com.au/blogs/news/91099207

Also refer to the imgix docs for info on the filters available:
https://www.imgix.com/docs/reference

-->
{% endcomment %}
{% if settings.enableImgix %}
	{% for i in (1..1) %}

		{% comment %}
		<!-- Check to make sure the src exists, and that imgix url theme settings is not blank. If blank, stop! -->
		{% endcomment %}
		{% unless src or settings.imgixUrl != blank %}{{ src }}{% break %}{% endunless %}


		{% comment %}
		<!-- Check to make sure the src has the Shopify CDN url in it. If it doesn't this does not need to run any further -->
		{% endcomment %}
		{% assign cdnUrl = settings.imgixShopifyUrl | strip %}
		{% unless src contains cdnUrl %}{{ src }}{% break %}{% endunless %}


		{% assign imgixUrl = settings.imgixUrl | strip %}


		{% comment %}
		<!-- Create a list of all the imgix filters we want to use -->
		{% endcomment %}
		{% assign filters = 'bri,con,exp,gam,high,hue,invert,sat,shad,sharp,usm,usmrad,vib,auto,bg,blend,bm,ba,balph,bp,bw,bh,bf,bc,bs,bx,by,border,pad,faceindex,facepad,faces,ch,chromasub,colorquant,dl,dpi,fm,lossless,q,mask,nr,nrs,colors,palette,prefix,dpr,flip,or,rot,crop,fit,h,rect,w,blur,htn,mono,px,sepia,txt,txtalign,txtclip,txtclr,txtfit,txtfont,txtline,txtlineclr,txtpad,txtshad,txtsize,txtwidth,trim,trimcolor,trimmd,trimsd,trimtol,mark,markalign,markalpha,markbase,markfit,markh,markpad,markscale,markw,markx,marky' | split:',' %}


		{% comment %}
		<!-- Build up the list of filters to add to the url -->
		{% endcomment %}
		{% assign imgWithQuerystring = "?" %}
		{% if src contains '?' %}{% assign imgWithQuerystring = '&' %}{% endif %}
		{% for _filter in filters %}
			{% if [_filter] %}
				{% assign imgWithQuerystring = imgWithQuerystring | append:_filter | append:'=' | append:[_filter] | append:'&' %}
			{% endif %}
		{% endfor %}
		
		{% assign newSrc = src | strip | replace:cdnUrl,imgixUrl | append:imgWithQuerystring %}

	{% endfor %}
	{{ newSrc | default:src }}
{% else %}
	{{ src }}
{% endif %}
{% endcapture %}{{ IMGIX | strip | replace:'	' | strip_newlines }}