Reference Glossary
Bit depth
The number of bits used to record each colour channel's tonal value per pixel, most commonly 8-bit (256 levels per channel) or 16-bit (65,536 levels per channel).
Why it matters in a DAM
Archival masters in a DAM are often stored at 16-bit rather than 8-bit because heavy colour correction on an 8-bit file can cause visible banding in gradients like skies, while a 16-bit file has enough intermediate tonal values to absorb the same edit smoothly. Once a file has been flattened and saved at 8-bit, the discarded intermediate values can't be recovered by later re-editing, so a DAM's master-retention policy should protect the highest bit depth version available, not just the finished delivery file.
A worked example
Common mistake
Archiving only the flattened 8-bit JPEG derivative as the permanent master and discarding the 16-bit RAW or TIFF, losing the tonal headroom needed for future heavy retouching or colour grading.
Bit depth sets how many distinct brightness levels each colour channel can record. An 8-bit channel has 256 possible values; a 16-bit channel has 65,536. Combined across red, green, and blue, an 8-bit image can represent about 16.7 million colours total — plenty for a finished, unedited photo, but a much shallower well to draw from once significant colour correction is applied.
The practical consequence for archiving shows up in gradients: push the shadows or highlights of an 8-bit sky enough and the limited number of intermediate values can produce visible banding, because there simply aren’t enough distinct tones to smooth the transition. A 16-bit master has far more values to redistribute during editing, which is why RAW and 16-bit TIFF are the preferred master formats for assets expected to undergo significant post-processing, with 8-bit reserved for finished delivery derivatives where file size matters more than editing headroom.
Frequently asked
What is bit depth?
The number of bits used to record each colour channel's tonal value per pixel, most commonly 8-bit (256 levels per channel) or 16-bit (65,536 levels per channel).
Why do DAM archival masters often use 16-bit rather than 8-bit?
Heavy colour correction on an 8-bit file can cause visible banding in gradients like skies, while a 16-bit file has enough intermediate tonal values to absorb the same edit smoothly.
How many total colours can an 8-bit RGB image represent?
About 16.7 million (256 x 256 x 256 combined across red, green, and blue) — plenty for a finished, unedited photo, but a much shallower well once significant colour correction is applied.
What's the risk of archiving only the flattened 8-bit derivative?
It discards the tonal headroom of the original 16-bit RAW or TIFF, losing what's needed for future heavy retouching or colour grading, since those intermediate values can't be recovered by later re-editing.
Why does banding appear in gradients?
Pushing the shadows or highlights of an 8-bit sky enough exhausts the limited number of intermediate values, so there aren't enough distinct tones left to smooth the transition.
Which bit depth should a DAM's master-retention policy protect?
The highest bit depth version available, RAW or 16-bit TIFF, reserving 8-bit for finished delivery derivatives where file size matters more than editing headroom.
Sources
- An 8-bit-per-channel image supports 256 tonal values per channel; a 16-bit-per-channel image supports 65,536. checked 2026-08-07 — Photography Life