在原有代码的基础上更进一步，能够在按Tab展开headline后自动显示当前subtree的图片。
;;; Only display inline images under current subtree.
(defun org-display-subtree-inline-images (&optional state)
"Toggle the display of inline images under current subtree.
INCLUDE-LINKED is passed to `org-display-inline-images'."
(interactive)
(save-excursion
(save-restriction
(org-narrow-to-subtree)
(let* ((beg (point-min))
(end (point-max))
(image-overlays (cl-intersection
org-inline-image-overlays
(overlays-in beg end)))
(display-inline-images-local
(lambda ()
(org-display-inline-images t t beg end)
(setq image-overlays (cl-intersection
org-inline-image-overlays
(overlays-in beg end)))
(if (and (org-called-interactively-p) image-overlays)
(message "%d images displayed inline"
(length image-overlays)))))
(hide-inline-images-local
(lambda ()
(org-remove-inline-images)
(message "Inline image display turned off"))))
(if state
(pcase state
('subtree
(funcall display-inline-images-local))
('folded
(funcall hide-inline-images-local)))
(if image-overlays
(funcall display-inline-images-local)
(funcall hide-inline-images-local)))))))
(define-key org-mode-map (kbd "C-c C-x C-v") 'org-display-subtree-inline-images)
;;; auto display inline images on Org TAB cycle expand headlines.
(add-hook 'org-cycle-hook #'org-display-subtree-inline-images)