Understanding bit depth

8-bit, 16-bit, 32-bit… What does bit depth mean, and what is a good bit depth to use?

In this class, Karl answers these questions as he explains what bit depth is and why it’s an important concept to understand in photography.

Quite simply, bit depth (also known as colour depth) refers to how much colour, brightness, and saturation can be displayed in a single pixel. Karl explains this in further detail throughout this class as he shows the visual differences between an 8-bit image and a 16-bit image. He also discusses the advantages and disadvantages of larger bit depths and why it’s still important to choose the right one and explains what bit depth is used for printing and why a higher bit depth is the best option for retouching.

This class covers the following:

  • What is bit depth/colour depth
  • How to change the bit depth of an image
  • How bit depth affects image quality — 8-bit vs 16-bit
  • The advantages and disadvantages of larger bit depths
  • How to determine colour depth
  • What is the best bit depth for retouching
  • What is the best bit depth for printing images

If you haven’t already, we recommend watching our ‘Fundamentals of post-production’ live show to better understand some of the concepts discussed in this class.

Other classes you may find of interest include:

If you have any questions about this class please post in the comment section below.

Comments

  1. It is worth noting, that the reason printers accept 8 bits – is due to the whole matter being even more complicated because printers use CMYK colour representation – which literally adds another dimension to the whole matter.

    Trouble with trying to show banding in videos is the compression. You’re editing the image in 16bit in photoshop, monitors can only display 10bit per pixel (P3) – but the screen grab saves it in a movie file that is even less than 8 bits per channel. So there’s a lot of interpolation and translation between different colour spaces going on.

    I used to work in music editing when I was younger, and I think some people prefer to edit and master photos (and music) in the format that these will be consumed in. So for instance, some retouchers will start working in 8 bit jpeg from the start – because that’s what the image will be consumed as. This was known as “working against” in music. Probably the same thing applies in photography.

    1. I don’t agree. The final image will be 8 bits of course, but the process of editing is completely different in 16bit. Is the same reason than I shoot 10bit video and export in 8 bit, I have more to play and deliver a better image.

  2. Great explanation, Karl. In my workflow, I usually reduce from 16 to 8 after I have finished retouching. Then I save it and the file size becomes smaller and more manageable. Question: can you go back from 8 to 16 if you would want to? Meaning is it destructive the 16 to 8 reduction?

    Cheers from sunny Buenos Aires,

    Jorge

    1. Hi Jorge, thanks but yes it would be destructive, after you’ve gone from 16 to 8 and save the file and close it then you won’t be going back to the same 16 bit if you decided to change from 8 back to 16 because it would only be continuing as 16 from that point onwards and any more subtle tones may have been lost. But to be honest if the retouching is finished, it’s finished and unlikely that any subtleties would matter! Tim Flach works mostly in 8bit for everything and look how great his work looks!

      1. Understood. To be honest with you, I cannot see any differences between 8 and 16. It could be that my monitor is not a calibrated one.

        Thanks a lot Karl.

        Indeed Tim photos look amazing.

        1. Hi Jorge, I don’t think it is the monitor, to be honest I can’t see any differences even on an Eizo. The only thing I occasionally notice is better banding on gradations with 16bit, but it is better practise if you are doing things like creating gradients or airbrushing new colour and B&D work to do that in 16bit so that you have those extra ‘steps’ of tones available. But I agree often it is difficult to notice any difference.

  3. Very clear explanation with sound recommendations for how to handle image bit depth from camera to print. Flawless presentation as usual Karl. Thank you!

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