Image-Dired is a facility for browsing image files. It provides viewing the images either as thumbnails or in full size, either inside Emacs or through an external viewer.
To enter Image-Dired, mark the image files you want to look at in
the Dired buffer, using m as usual. Then type C-t d
(image-dired-display-thumbs). This creates and switches to a
buffer containing image-dired, corresponding to the marked files.
You can also enter Image-Dired directly by typing M-x
image-dired. This prompts for a directory; specify one that has
image files. This creates thumbnails for all the images in that
directory, and displays them all in the “thumbnail buffer”. This
takes a long time if the directory contains many image files, and it
asks for confirmation if the number of image files exceeds
image-dired-show-all-from-dir-max-files.
With point in the thumbnail buffer, you can type <RET>
(image-dired-display-thumbnail-original-image) to display a
sized version of it in another window. This sizes the image to fit
the window. Use the arrow keys to move around in the buffer. For
easy browsing, use <SPC>
(image-dired-display-next-thumbnail-original) to advance and
display the next image. Typing <DEL>
(image-dired-display-previous-thumbnail-original) backs up to
the previous thumbnail and displays that instead.
To view and the image in its original size, either provide a prefix
argument (C-u) before pressing <RET>, or type
C-<RET> (image-dired-thumbnail-display-external) to
display the image in an external viewer. You must first configure
image-dired-external-viewer.
You can delete images through Image-Dired also. Type d
(image-dired-flag-thumb-original-file) to flag the image file
for deletion in the Dired buffer. You can also delete the thumbnail
image from the thumbnail buffer with C-d
(image-dired-delete-char).
More advanced features include image tags, which are metadata
used to categorize image files. The tags are stored in a plain text
file configured by image-dired-db-file.
To tag image files, mark them in the dired buffer (you can also mark
files in Dired from the thumbnail buffer by typing m) and type
C-t t (image-dired-tag-files). This reads the tag name
in the minibuffer. To mark files having a certain tag, type C-t f
(image-dired-mark-tagged-files). After marking image files
with a certain tag, you can use C-t d to view them.
You can also tag a file directly from the thumbnail buffer by typing
t t and you can remove a tag by typing t r. There is also
a special “tag” called “comment” for each file (it is not a tag in
the exact same sense as the other tags, it is handled slightly
different). That is used to enter a comment or description about the
image. You comment a file from the thumbnail buffer by typing
c. You will be prompted for a comment. Type C-t c to add
a comment from Dired (image-dired-dired-comment-files).
Image-Dired also provides simple image manipulation. In the thumbnail buffer, type L to rotate the original image 90 degrees anti clockwise, and R to rotate it 90 degrees clockwise. This rotation is lossless, and uses an external utility called JpegTRAN.