Originally Posted by John Wheeler
The client is King so I now understand you issue. I think you have a good workaround. I will poke around and see if there is another easily accessible JPEG converter that will do a better job.
Do you use a Windows or Mac machine? Not all options are supported on both.
No luck with other JPEG options. IrfanView had the least compression including an option to avoid subsampling yet found out that even with the option checked, the chroma channels still had sub-sampling applied. I concluded other workarounds would be better at this point such as your approach with PNGs.
However, another option if you client accepts them is a JPEG with a Clipping Path. That is a very common way to have a JPEG file with an effective embedded mask (its actually a Vector Path) so the image overlays with whatever the background is on the web page. Clipping paths are supported in Photoshop so thought I would mention this option.