Why is there masses of hidden data in some JPEGs?

i guess, not precisely photoshop question, although photoshop cc 2015.5.1 i'm using. download product photos provided equipment makers. they're in png format. resize, crop, alter canvas size appropriately nice look, making sure end 760 pixels wide, , save jpg @ '8' on scale (medium). results in file of 50kb 150kb depending on complexity of image. point snappy website performance.

 

but every (maybe 5% of time), when file size ... 2.4mb or equally ridiculous. we're talking 8 bit rgb here, no weird channels or paths or anything. 2.4mb 1 saved (using workaround) 46.2kb. experimenting quality slider, still 2.4mb @ '0'. @ '12' 2.5mb. suggests there's 2.4mb of unnecessary data hidden in file somewhere.

 

workaround save bmp (this strips away bmp doesn't support, except picture data itself), open , re-save jpg. works enough , it's not burdensome, fascinated hidden data might , why jpg encoder doesn't eliminate it. incidentally, if open original file in windows paint, resize , save jpg, ends small file size.

 

i can provide sample image if required.

https://forums.adobe.com/search.jspa?place=%2fplaces%2f1413024&sort=updateddesc&q=ancestor +metadata

More discussions in Photoshop

adobe