What is the benefit of 16 bit over 8 bit?

[Ilovemycam]

Lightroom has 2 options to save as a Tiff file, 8 bit or 16 bit. I tried both and can't see any difference. The 16 bit doubles the file size. What is the benefit of 16 bit?

 

[480sparky]

You retain more of the data. For printing, exporting, emailing etc, an 8-bit would be just fine. But for further editing, you want to keep that 16-bit data.

 

[KmH]

Photo Editing Tutorials

8-bits can only represent 256 gradations of color/tone.

Photoshop actually only uses 15 of 16-bits but 15-bits can represent 32,768 gradations of color/tone.

8-bit images have little, if any editing headroom. Gradients are problematic because with only 256 gradations of color/tone banding and posterization can become visible.

Some of the tools in Photoshop would require an unacceptable length of time to do all the calculations necessary for the tool to be available as a 16-bit depth tool. So those tools are 'grayed out' and unavailable for use when editing 16-bit depth images.

Camera Raw/Develop Module (ACR) is a parametric editor while Photoshop is a raster graphics editor that also has some vector graphics tools/functions, so they work differently.

8 digital bits = 11111111
Each place can only be a 1 or a 0 (binary (digital) or Base 2 numbering system).

From left to right each 'place' has the following values when the place is a 1 • 128, 64, 32, 16, 8, 4, 2, 1 • added together they = 255. Add 0 (00000000), and 8-bits can only represent 256 discrete values.

10010111 = 128 + 16 + 4 + 2 + 1 = 151

 

[Ilovemycam]

Thanks for the info.

For 6 x 6 BW scans is 8 bit OK or should I be doing it in 16? If I'm dodging and burning a lot, will the 16 bit have more room for this?

That color gaduation chart at the link is a nice learning tool KmH. Would it work the same with BW? Or do you need more bits for color graduations and not for BW?

 

[480sparky]

Color or grayscale.... bits are bits, and shades are shades. With color, you get three sets.... one with grayscales. Again, the more data you keep, the more editing options you have in the future. Just convert to JPEG when you're ready to print or upload.