The thing is when you use display the result of curl in a browser, it is the browser that goes off and gets the images from the storage location -- not curl. I was thinking of modifying all the different img directives (and there are a lot of different ones mainly due to different colors, etc) to use one simple image that I could include as an attachment to the email. I would also then want the report to actually be in the body of the email message so the email client would know how to embed the simple image properly.
The other possibility is to completely replace the img and modify the table cells with different background colors. The graphs would have the different colors but it would look flat.
Creating a PDF from the report might be another idea but I need to check for scripts out there that can render HTML into a PDF.
I might find time to work on this again this weekend... then again nice weather tends to pull me outside