Scan Channel Isolation - Epson 4990 48bit Color Filters

[DigitalDude]

Recently, have been experimenting with BW scanning. Currently testing whether it is possible / preferable to scan BW in 48 bit RGB WITH channel isolation using Color Filters (General->Options->Special) separated for each channel?

I have scanned four BW files in 48bit RGB mode, one each with White, Red, Green and Blue--so it's a "selectable" feature. I am finding that with my CCD scanner (Epson 4990) and Silverfast Ai (v6.5.5), there are no perceptual differences between the four scanned files. The color filter/channel isolation feature DOES work in 16bit grayscale scans and delivers perceptual differences that one would expect.

I believe that BW scanning in 48 bit RGB is preferable to 16 bit grayscale in general. Therefore, I'm trying to determine if channel isolation at the scanning stage really does work in 48bit RGB mode with the Epson 4990 and Ai? And, would 48 bit scans with color filters provide obvious differences between the channels as in 16 bit scans?

Appreciate any thoughts...

[LSI_Muenier]

Dear DigitalDude,

the "Color Filter" is used in GrayScale mode, only.

Then, it determines which of the RGB channels to choose,
or to combine them in a weighted way in the case of "White".

When you do an RGB scan, then you get all three channels in one pass!
You can then simply choose Red, Green, or Blue from the resulting RGB image.

Best regards
Martin