The hidden text area below contains the color-wheel image in base64 (a text format) that the javascript will convert to an actual image and display in the hotspot (div) above. Google "convert image to base64" to find a free tool that will convert your image to base64, like this one. (Using base64 is the only way I found to avoid cross-origin security failures when trying to access image data, so you can host it anywhere.)

The hotspot (div) below – that also runs the javascript OnLoad – will contain the image specified in base64 below. It needs to be the same size as the image specified in base64.

Click the color-picker.