Grayscale output as RGB?

[hansm]

My Sony Bravia TV does not accept for display jpeg's with only one gray channel but instead needs rgb-pictures, albeit with all three channels the same.
It seems most efficient to scan and store the black&white negatives as 16bit HDR then convert them with 16->8, formatted for the TV-dimensions. But a further step in an image processing program is then needed to change the mode from grayscale to rgb and save the picture again.
I tried to circumvent the second step by doing output in HDR8 as rgb-mode pictures by choosing 48->24 but this did not result in the structure needed. Is there a manner to get this done in HDR8, thereby circumventing the second step in another program?

[LSI_Ketelhohn]

Dear customer,

You would already have to scan the images in 48bit HDR to be able to keep the RGB channels.
When they are saved in 16bit HDR the key channel is the only one kept.
I am afraid expanding an 16 bit image to 48 bit again is not a workflow we have anticipated.

Kind regards,
Arne Ketelhohn.