System, device, and method of image processing, particularly utilizing machine learning and computer vision. A computerized method includes: obtaining a user-image of a user of an electronic device; generating a user-mask image that corresponds to the user-image processed to exclude background image-data of that user-image; receiving a product-image of a particular product; generating from the product-image a product-mask image that corresponds to the product-image processed to exclude background image-data of the product-image; receiving the product-mask image and the user-mask image, and generating from them a combined or composite user-and-product image which depicts that particular user engaging with that particular product.