Bit Depth for Adjustments


Today’s Question: Would it be better to apply routine adjustments to an image while the file is still 16-bit per channel mode?

Tim’s Quick Answer: Yes! I always recommend working in the 16-bit per channel mode for your “master” image, only using the 8-bit per channel mode to save derivative copies of the photo.

More Detail: When you share a photo online or produce a print of a photo, you really only need 8-bit per channel color. That translates into more than 16.7 million possible color and tonal values, which happens to be about the same number of values the human visual system is estimated to be capable of seeing.

However, there are advantages to having some additional “headroom” for your adjustments. When you apply an adjustment to a photo, you will often lose a degree of detail in the process. For example, a strong increase in contrast might cause a reduction in the level of detail in the brightest highlights and the darkest shadows.

When working with an image in the 16-bit per channel mode, you have more than 281 trillion possible color and tonal values available. Thus, even with very strong adjustments you will likely still have more than enough information to support the 8-bit per channel mode that represents a baseline in terms of how much information you need to share an image with optimal quality.

Therefore, I highly recommend always working with your “master” image in the 16-bit per channel mode. The 8-bit per channel mode should only be used for saving copies of an image for sharing with others.

It should be noted, by the way, that converting an 8-bit per channel image to the 16-bit per channel mode does not provide the benefits available for true 16-bit per channel images. In other words, you’ll need to start with a RAW capture in order to retain the full bit depth of the original capture. Then, working in 16-bit per channel mode will ensure maximum flexibility for your master image, so you’ll be able to share that image with the best quality possible.