Bypassing of the filepath for creating thumbnails for images in s3 bucket simultaneously

My requirement is to create three images of different sizes simultaneously on a S3 bucket. I found a node module namely node-s3-uploader which suits my requirement. As per the documentation, if I want to upload an image, I need to provide the image path. But I am uploading a file not from my local disk but I am posting it through Advanced Rest Client a Chrome Plugin. Can somebody Suggest me how can bypass the image path description for the node-s3-uploader?

If it is not possible, is their another mechanism that I need to follow?