how to convert html to jpg

As dM already pointed out, it's

PrtScr = Whole Desktop
Alt+PrtScr = Active Window

The Ctrl key doesn't feature in either of the shortcuts.

Cheers,
Dave

A good html to jpg, png images converter is the one from hiqpdf

I think there are many software convert html to jpg. you can capture and save images.

There is no difference between "alt+prtscr and crtl+alt+prtscr". To Convert complete page into JPEG it is better to install virtual printing drivers such as "Virtual Image Printer driver" or "Zan Image Printer"

if you are using firefox, they have a few add ons (can't remember the exact name) that copy the whole page, including the offscreen sections, which you can then paste into photoshop.