Scanner "bits" - What's the Deal

[carney2]

In checking the Nikon Coolscan V Ed scanner vs. the 5000 ED, I find that a major difference seems to be "14 bits" for the Coolscan V vs. "16 bits" for the Coolscan 5000. Besides speed (not a major concern for me), what does this mean?

[Trevor Ash]

Wow. I didn't know they made film scanners yet that actually utilized 16 bits of color information. The difference between 14 and 16 in numbers is significant, but when it comes to the actual results I wouldn't think it be be a very noticeble difference. Keep in mind I haven't actually compared them myself so this is speculation.

What the 14 and 16 bits means is simply how much differences in red, green, and blue color they can capture, and save to. Some scanners can probably "see" greater than 8 bit color but they aren't capable of producing anything greater than 8 bit images.

With today's software, you're either going to work in 8 bit mode or 16 bit mode. There's no inbetween as concerns the software because it'll just use the 14 bits of information in a 16 bit world.

Each pixel in an RGB image is comprised of a real absolute value for each of the three colors Red (R), Green (G), and Blue (B).

The amount of color values possible in an 8 bit image: 256
The amount of color values possible in a 14 bit image: 16,384
The amount of color values possible in a 16 bit image: 65,536

Keep in mind, 16 bit images are MUCH LARGER in filesize than their 8 bit counterparts.

I hope this helps some.

[Franglais]

In checking the Nikon Coolscan V Ed scanner vs. the 5000 ED, I find that a major difference seems to be "14 bits" for the Coolscan V vs. "16 bits" for the Coolscan 5000. Besides speed (not a major concern for me), what does this mean?

My understanding - I may be wrong on this - is that the Coolscan 5000 has greater dynamic range than the Coolscan V i.e. it can read the deep shadow detail in a very dense, contrasty slide which the Coolscan V would see as black.. The extra bits are used to record the additional information.

However most slides and all colour negatives never reach this level of density and even on the Coolscan V the full 14 bits of information is rarely used. The Coolscan V is enough for most people.

Note also that you can't actually do anything with a 16-bit image except keep it as a TIFF and look at it in Photoshop. As soon as you convert it to a JPG or do anything with it in Windows it gets transformed into an 8-bit image. An 8-bit image can represent 256x256x256 = 16 million colours, which is much more than the eye can distinguish anyway.

Charles