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Message-ID:  <[log in to unmask]>
Date:         Mon, 11 Aug 2003 17:09:34 -0400
Reply-To:     ImageJ Interest Group <[log in to unmask]>
Sender:       ImageJ Interest Group <[log in to unmask]>
From:         Wayne Rasband <[log in to unmask]>
Subject:      Re: Why is 16->8 bit image conversion done this way?
In-Reply-To:  <[log in to unmask]>

> We are doing some quantitative analysis on images (both 8-bit and
> 16-bit) and wanted to set thresholds which were similar in both image
> sets.
>
> I originally thought that the bit depths just scaled linearly. When I
> noticed it didn't, I poked around in the code and saw the Calibration
> class.

ImageJ does linear 16-bit to 8 bit conversion. It scales from min-max
to 0-255 when "Scale When Converting" is checked in
Edit>Option>Miscellaneous, otherwise it scales from 0-65535 to 0-255.
Can you provide a simple example that shows otherwise?

> I'm just curious what is the history behind this chunk of code.

The Calibration class, which stores spatial and density calibration
information, is not used when converting from 16-bit to 8-bits.

-wayne

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