Japan's Submarine UB I-25 - Looking for an expert

I am gearing up for modelling the WW II Japanese submarine UB I-25, basing it off existing models of similar submarines (I-19, or I-26).

I picked up the original postcard issued in Japan commemorating the submarine:

Now, I have noticed that this image differs considerably in markings from the other artwork I have found of the sub, such as:

Notably, the lettering of the commemorative post card, which is confirmed as being original and from Japan, is dark and differs in content.  The post card was obviously of Japanese origin, the photo appearing to have been black and white and then colorized.  It is conceivable that the post photo may have originally been doctored, but to have the lettering drastically different is odd.

So, what is the real deal?  The lighter coloration and UBJ25 lettering in black, or the artist's conceptions?