What happens to the size and intensity of the image if a part of a lens is covered ?

When a part of a lens is covered, every point of the remaining uncovered portion still contributes to forming the complete image. Therefore, the size and position of the image remain unchanged because these depend on the focal length and object distance, not on the aperture of the lens.

However, since less light passes through the lens, the intensity (brightness) of the image decreases.