You can replace an image in the template file with dynamic content by writing the following expression after the image in the document:
{%=replaceImage(data)%}
The value of data should be Base64-encoded data URI string.
The expression replaces the content of image preceding this expression, therefore, it should be placed immediately after the image we want to modify.
When the image data is not valid value, the following error is printed:
Image data should be in valid base64-encoded data uri format!
The following error tells you that the marker expression is placed in a wrong position (perhaps before instead of after the image tag):
Did not find image to replace. The location of target image must precede the replaceImage() function call location.