Why would someone convert a RAW file to an 8-bit TIFF for Photoshop retouching?
Asked 8/17/2014
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I saw a Photoshop retouching tutorial where the instructor converts a RAW file to an 8-bit TIFF before doing frequency separation. Since RAW files typically contain 12–14 bits of data, why would an experienced editor choose 8-bit TIFF instead of keeping more bit depth? Is there any technical advantage, or is it mainly for compatibility and smaller files?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
11y ago
2 Answers
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The only advantages to saving your RAW files as 8-bit is for memory conservation or if certain tools only work with 8-bit images. There is no advantage from a quality point of view, if you're going to do a lot of editing especially in a wide colour space then you may get posterisation when working with only 8 bits.
Regarding colour spaces, it is advisable to use the widest space possible when editing, even if it is wider than your target colour space. This is because you might do something that moves the colours outside the narrow gamut only to perform a later step that moves them back in. If you were editing in that narrow gamut space the colours would get clipped and the final result would be different.
Originally by user1375. Source · Licensed CC BY-SA 4.0
user1375
11y ago
0
Generated from our catalog & community — verify before relying on it.
Usually, there’s no image-quality advantage to converting a RAW file to 8-bit TIFF before editing. The main practical reasons are:
- smaller files / lower memory use
- faster performance
- compatibility with tools or workflows that only support 8-bit
For heavy editing, 16-bit is generally safer. Big exposure, contrast, or curve changes can cause posterization or banding more easily in 8-bit, especially in wide color spaces like ProPhoto RGB.
Why 8-bit can still be acceptable in some workflows:
- after demosaicing and gamma encoding, 8-bit can be visually sufficient for moderate edits
- many final outputs (web, many print workflows, displays) don’t benefit much from higher bit depth
- if the retoucher already has the RAW conversion where they want it, the remaining Photoshop work may not stress the file enough to show 8-bit limits
So the short answer: it’s usually a workflow/performance choice, not a quality upgrade. If you expect aggressive adjustments, keep the file in 16-bit TIFF/PSD as long as possible; if edits are modest, 8-bit may be fine.
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