Hi Nehil,
It is not fully clear what you are trying to achieve.
A direct image cannot be attached to the attachments section of an email, although an image
file can be.
The Attachments collection of the Send Message action of the Email object only accepts a path so it does not allow to change it to an Image data type.
View attachment 961
If you would like to embed the image into the body of an email even then the file has to be first attached to the email and then pass its path as a HTML cid parameter.