I have a mystery for one very smart individual when it comes to dp?

While I was adding a watermark to this picture, I noticed that the resolution is 200 dpi and not 72 dpi like all the others. I have an hp photosmart 435 3.2 megapixel digital camera. Normally, I would use the automatic settings except for the white balance and ev. On this day I changed the iso to 200 for fast moving objects (the waves crashing on the beach). I also noticed that because of the higher resolution this picture does not pixalate nearly as much and the image seems sharper. When I edited the image I had to increase the contrast by 50% and darken it by 10 or 20% to get the desired result. I don't get it. I went back and took some pictures at iso 200 but still, the same thing, 72 dpi. There is a noticeable difference between the quality of this picture and my other pictures. I don't know how to explain it. I have taken thousands of pictures with this camera and read the users manual more times...
http://f3.yahoofs.com/blog/44ed12f5z1288...

http://f7.yahoofs.com/users/S3sIG2jSawCp...

I DON'T KNOW WHAT YOU DID, BUT THE PHOTO IS BEAUTIFUL. DID YOU HAPPEN TO SHOOT THE PHOTO IN A DIFFERENT MODE, SUCH AS UNCOMPRESSED?

To edit, did you convert it to a data file? If so that is probably the source of the difference.

ok..
setting is 72 as apposed to 200 dpi , on computer,...
the camera,
Photosmart 435
http://h10010.www1.hp.com/wwpc/us/en/sm/...
pdf manual:1.6 mb save as
http://h10032.www1.hp.com/ctg/Manual/bpy...
pg 30...
check image quality is on high, better or best,
good is for internet (72 dpi),
if not, then after taken, editing can not undo dpi,
you can add dpi to image size in photo editor,
and may turn off constrain proportions when increasing image size, so image stays ~5x6", but pixels increase only,
but quality may not be there...

http://en.wikipedia.org/wiki/Film_speed#...
http://webpages.charter.net/bbiggers/DCE...
..