Why doesn't Windows XP open 16-bit/48-bit files?

[John C Murphy]

I run Windows XP Home 2002 edition on my PC and the Windows Picture and Fax Viewer won't open 16-bit grayscale or 48-bit color files from my scanner. Photoshop has no problem with them. Why is this? Do I need to upgrade?

[John_4185]

You are saving as TIFF, is my guess. In any event, that's the way it goes with the greater bit-depth images.

You need a different viewer. Go to GOOGLE and type 'download irfanview', go to twocows.com, install it and be happy.

[Stan. Laurenson-Batten]

Many thanks John.

This bit depth problem has baffled me for some time. Stan.

[Donald Qualls]

The simple answer is that, at the time Windows XP shipped, there were probably only a few hundred people in the US scanning at 16 bits per channel; there certainly weren't a lot of scanner models that operated at that level (some, yes -- I have one that's nine years old and outputs 16 bpc). No reasonably common display hardware supports 16 bits per channel (32 bit color is the highest I've seen), and images aren't commonly distributed in 48-bit even if they're scanned and stored that way now.

Microsoft doesn't spend money supporting stuff that a) hardly anyone has, and b) isn't being or about to be offered by one of their "business partners".

The simple way around this is to change the file association for TIFF to an application that can handle 16 bits per channel.

[Mike Kovacs]

More importantly, video cards and computer monitors are 8 bit per channel devices. Even what photoshop is displaying on the screen is not truly 16 bit, but of course all of the extra data is in the file.

I don't think any printers really handle 16 bit files as well. The real utility is to have the extra data editing overhead.