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"How can I capture an image with the blinkie background and the resultant after glow?"
If you mean you want to save to a file the blinkie image that shows on the LCD the answer would be you can't.
If that's not what you are asking provide the info indicated by Danny and clarify the question.
Display it on the LCD screen after you take the image and record a video with your phone maybe? Other than that you are asking the camera to create a video of exposure data of an image or video that may or may not have been recorded to a memory card. I don't see a huge demand for that ability.
"... I want to save the blinkie image to a file that shows on the LCD screen."
You want to put it back on the camera, too? I don't think that is possible but since I have never and have never wanted to, I have never tried. The back of the camera LCD screen is for facsimile display of what you are taking or what you just took as a photo.
This is a public forum mostly answered by users just like you and not Canon employees. So any suggestions for future features posted here will fall on deaf ears.