Errors when converting from 32-bit uncompressed TIF to 16- or 8-bit?

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Errors when converting from 32-bit uncompressed TIF to 16- or 8-bit?

Leonardo Guizzetti
Hello all,

I think this message belongs here. I've noticed that when I generated an
uncompressed 32-bit TIF using Python, then open it in FIJI, the image will
eventually be converted (in FIJI) to a 16-bit. However, in a test image
which only has pixels valued at 0 or 100, when I downsample, the dynamic
range is expanded to fill the new bit-depth. My pixel values now max out at
65535 or 256. Is this an error, or if not, what is the proper way to shrink
the bit-depth of my images?

I have uploaded a sample image using FIJI, called "points.tif" which you
can use to verify the problem.

Thanks,

Lenny

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Re: Errors when converting from 32-bit uncompressed TIF to 16- or 8-bit?

ctrueden
Hi Lenny,

> I've noticed that when I generated an uncompressed 32-bit TIF using
> Python, then open it in FIJI, the image will eventually be converted
> (in FIJI) to a 16-bit.

I cannot reproduce the behavior you describe.

With the SCIFIO option [1] turned on or off, using File > Import >
Image..., using File > Import > Bio-Formats, all yield a 32-bit TIFF with a
zero background and single pixel points with value 100.0.

Can you describe the exact steps you used to import this image into Fiji?
Is your Fiji up to date? [2]

Regards,
Curtis

[1] http://imagej.net/SCIFIO
[2]
http://imagej.net/FAQ#How_can_I_verify_that_my_ImageJ_is_really_100.25_up_to_date.3F

On Fri, Sep 12, 2014 at 7:14 PM, Leonardo Guizzetti <
[hidden email]> wrote:

> Hello all,
>
> I think this message belongs here. I've noticed that when I generated an
> uncompressed 32-bit TIF using Python, then open it in FIJI, the image will
> eventually be converted (in FIJI) to a 16-bit. However, in a test image
> which only has pixels valued at 0 or 100, when I downsample, the dynamic
> range is expanded to fill the new bit-depth. My pixel values now max out at
> 65535 or 256. Is this an error, or if not, what is the proper way to shrink
> the bit-depth of my images?
>
> I have uploaded a sample image using FIJI, called "points.tif" which you
> can use to verify the problem.
>
> Thanks,
>
> Lenny
>
> --
> ImageJ mailing list: http://imagej.nih.gov/ij/list.html
>

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ImageJ mailing list: http://imagej.nih.gov/ij/list.html