Challenge with big TIFs conversion

[Co60]

Hello,

I am having a challenge here, I tried to convert a 16Bit TIFF of 86 MB and 300dpi to a small, web-usable, JPG.
The goal would be a size of 1024x768 with a "normal" file-size of let's say up to 200kB.
But whatever I try the file-size stays between 1.5 and 2.3 MB .

-resize 1024x768 -quality 80 -sharpen 1.5 => 2.3 MB
-resample 72x72 -quality 50 -sharpen 1.5 => 1.9 MB (and slightly to big, too)
-resize 1024x768 -quality 50 -sharpen 1.5 => 1.7 MB
-resize 1024x768 -quality 10 (!) -sharpen 1.5 => 1.5 MB (and result unusable of course ...).

Can anybody point my nose on what I am missing here?

Thanks in advance!

P.S.: Version used is 6.3.6-3-Q16 Windoze

[Bonzo]

Try adding -strip to your code and see if that reduces the size further.

[Co60]

OK, some more tests ... found out that the TIFF is a CMYK so
the standard conversion procuded a 32 Bit CMYK JPEG ...

however
-resize 1024x768 -colorspace rgb -depth 24 -quality 85 -sharpen 1.5
still produces 1.65 MB ...
saving this result again with XNView Q85 gives the desired result ...
189 kB of 24 BIT JPG ...

Still taking your input on how to achieve the same with IM, pals !

[Co60]

WOHOOO!!! You're my man, Bonzo!!!

-colorspace rgb -depth 24 -resize 1024x768 -quality 85 -sharpen 1.5 -strip

Result is 185 kB ...

I was first thinking about IPTC or EXIF but those were both empty - so there
must have been some other "profiles or comments" in there.

Thanks a lot, Bonzo!

[Bonzo]

Glad to have been of help, as you say there is a lot of info hidden away in images.