Evaluate the form below, the deleted image remains displayed partially
in the window.
In my environment, (window-pixel-height)=>560, (frame-char-height)=>16.

The attached image is the screenshot of the result.

(let* ((buf (generate-new-buffer "tmp"))
       (w 512)
       (h 512)
       (pbm (concat (format "P4\n%d %d\n" w h)
                    (make-string (* (/ w 8) h) ?U))))
  (switch-to-buffer buf)
  (dotimes (i 50)
    (insert-char ?X i)
    (insert ?\n))
  (goto-char (point-min))
  (redisplay t)
  (insert-image (create-image pbm 'pbm t :scale 1))
  (redisplay t)
  (delete-char -1))