"compressed bits/pixel" term in JPEG/EXIF data

[xpatUSA]

Is it possible to edit the Compressed bit per pixel?
I try to use exiftool to add certain details in Compressed bit per pixel, but I don't get the right command to edit it.

Nope. These 'bits per pixel' (bpp) are different from color-depth bits e.g 8 bpc.

The bpp is calculated from the file size in bits and the image size in pixels (H x W), so trying to edit it might not work.

For example Stack Overflow says that, for a ~20Kb image 425x282px:

"Bits per pixel = Bits/Pixel, 1 Byte = 8 Bits
=> JPG (20635 * 8 bits) / (425 * 282 pixels) => 1.38 bits per pixel

Also, don't mix this up with the term "bits per pixel" that is used for the color depth of an image which should be 24 bits per pixel (meaning 8 bits for each red, green and blue)."

1.38 bpp ain't all that good, by the way . . anything over 5 or 6 is pretty good image quality-wise.