Convert 16bits to 8 bits

good morning! I would like to know how I can convert a 16-bit multichannel image to an 8-bit image without changing the intensity ratio in each channel

Hi @clara,

Welcome to the forum.

By default, conversion to 8-bit uses the min/max values of the brightness / contrast settings when quantizing, meaning that you’ll need to make sure the brightness / contrast for all your channels are the same before doing the conversion.

You can do this easily with

  • Image > Adjust > Brightness / Contrast
  • click Set
  • check the Propagate to the other # channels of this image
  • then convert to 8-bit.


Also check out the documentation here

Converts to 8-bit grayscale. ImageJ converts 16-bit and 32-bit images to 8-bit by linearly scaling from min–max to 0–255, where min and max are the two values displayed in the Image▷Adjust▷Brightness/Contrast… [C]↓. Image▷Show Info… [i]↓ displays these two values as Display range . Note that this scaling is not done if Scale When Converting is not checked in Edit▷Options▷Conversions…↑ …)

Hope that does the trick


Thank you very much, John.
I was answering an exam of the Fiji course, and the correct option to that question, was previously carried out the gray-scale images with which they were taken, eg. 10, 12 bits (this is serious so as not to vary the intensity ratio of each in each image.
Thank you very much for your response!