These images are taken from a receipt printed with a thermal printer. The up-down axis of the receipt is horizontal here. A careful observation reveals vertical lines along the length of the receipt. These lines are printed using heated elements on a cylinder. As can be seen from the image, each character is created with 25 to 30 vertical lines. These lines are broken at precise locations to imprint the shape. The resolution of the line breaks is also limited. This limited step like resolution of the line breaks can be seen in the last image where the character W is shown.