Image tags in "Twitterfeed-Ping.fm-Blogger" are eliminated?

Sorry,
I wonder, why pinging from Twitterfeed to Ping.fm, to a Blogger network, eliminate all <img> tag and some other HTML tags? (except first image which is added to the end.)

Does this elimination occur at Ping.fm side, or at Twitterfeed side?

(1) This is not happened when the feed item is sent to Ping.fm contained only "summary" section.
The image tag and formatting tags in "entry.summary" feed's element will be delivered well to the Blogger.

e.g. feed item from Engadget.com's RSS:


(2) But, in case a feed item contained "entry.content" feed's element, then image tags and some other formatting tags will be eliminated.

e.g. feed item from Mashable.com's RSS:

(first image tag - retweet - is added to the end)

Original feed content:


CMIIW, TIA.