I found another colorized photo of Twain and used it in a blog post (July 2012) which can be found here:http://proartz.blogspot.com/2012/07/connections-non-fiction.html
It was taken by art photographer Alvin Langdon Coburn (1882-1966) at Stormfield. Coburn's autochromes where among the first colored photos. 
When I searched today (in an attempt to remember where I originally found that image) I found other colored Twain photos with a google search: https://www.google.com/search?q=alvin+langdon+coburn+photograph+of+Mark+Twain&client=safari&rls=en&tbm=isch&tbo=u&source=univ&sa=X&ei=W_0bU-rYM8T50AG6nYGoBg&ved=0CCgQsAQ&biw=1345&bih=975
Not all the photos at that last link were by Coburn, but the ones of Twain in bed and the ones by the window seem to look similar in photographic style. 
I noticed that there are images there for the exact same photo in a mirror image of the one on my blog, so I'm not sure which one is the correct one. I am thinking, however, that Twain might have smoked his cigars left-handed so he could write with his right hand, so the orientation on the one I posted may be correct.  (I saw a couple of photos at that link with Twain holding a pipe in his left hand.)
I also found a book "Mark Twain with photographs by Alvin Langdon Coburn" by Archibald Henderson for $19.10 (Barnes and Noble) in paperback: http://www.barnesandnoble.com/w/mark-twain-with-photographs-by-alvin-langdon-coburn-archibald-henderson/1026603531?ean=9781290953719
or for $22.49 (Amazon):http://www.amazon.com/Twain-photographs-Alvin-Langdon-Coburn/dp/B00AU6MVQA/ref=sr_1_2?ie=UTF8&qid=1394344080&sr=8-2&keywords=Mark+Twain+with+photographs+by+Alvin+Langdon+Coburn
(You cannot view the photos at either site.)
Apparently this is a reproduction of a book published some time before 1923.
Carol
========== “Life should not be a journey to the grave with the intention of arriving safely in an attractive and well-preserved body, but rather to skid in sideways, chocolate in one hand, wine in the other, body thoroughly used up, totally worn out, and screaming 'Woo Hoo! What a ride!'" -Unknown