Converting 32-bit to 8 bit images

[Dr Adam Cliffe]

Hi Everyone,

I'm trying to do some spectral unmixing using Joachim Walter's Spectral Unmixing plugin. I can get it to work fine, and at the end it produces 2 32-bit stacks. My problem is converting these back to 8-bit images.  The 32-bit image has a range of -330.8  to +577.82. The range I'd like to keep in the 8-bit image is from say -40 to +353. (as seen by adjusting the max/min range.

I've tried setting this range, then hitting 'Apply' in the Brightness/contrast window. Whatever I do, when I convert to 8-bit, I get the same image as if I convert the original 32-bit image.

Can anyone tell me where I'm going wrong or offer any good advice for converting 32-bit to 8-bit?

thanks

Adam
 


Dr Adam Cliffe
Research Scientist, Rorth Lab

Institute of Molecular and Cell Biology
61 Biopolis Drive
Proteos
Singapore 138673

tel: [phone]

[Daniel James White]

Hi Adam,

On Sep 27, 2011, at 6:00 AM, IMAGEJ automatic digest system wrote:

> Date:    Tue, 27 Sep 2011 11:22:41 +0800
> From:    Dr Adam Cliffe <[hidden email]>
> Subject: Converting 32-bit to 8 bit images
>
> Hi Everyone,
>
> I'm trying to do some spectral unmixing using Joachim Walter's Spectral Unmixing plugin. I can get it to work fine, and at the end it produces 2 32-bit stacks. My problem is converting these back to 8-bit images.  The 32-bit image has a range of -330.8  to +577.82. The range I'd like to keep in the 8-bit image is from say -40 to +353. (as seen by adjusting the max/min range.
>
> I've tried setting this range, then hitting 'Apply' in the Brightness/contrast window. Whatever I do, when I convert to 8-bit, I get the same image as if I convert the original 32-bit image.
>
> Can anyone tell me where I'm going wrong or offer any good advice for converting 32-bit to 8-bit?

In imageJ, 8 bit always means the range is 0-255
it can not be -40 to +353

but, if in the contrast / brightness tool you set max and min to -40 and 353 (use the set button to enter the numbers manually into the max and min fields)
then convert to 8 bit, you should get that which you desire.

you don't click Apply, rather one uses Set.

THe imageJ manual should explain why!

Dan

>  
>
> thanks
>
> Adam
>
>
>
> Dr Adam Cliffe
> Research Scientist, Rorth Lab
>
> Institute of Molecular and Cell Biology
> 61 Biopolis Drive
> Proteos
> Singapore 138673
>
> tel: [phone]

Dr. Daniel James White BSc. (Hons.) PhD

Leader - Image Processing Facility,
Senior Microscopist,
Light Microscopy Facility.

Max Planck Institute of Molecular Cell Biology and Genetics
Pfotenhauerstrasse 108
01307 DRESDEN
Germany

[phone] (German Mobile)
[phone] (Work phone at MPI-CBG)
[phone] (Fax MPI-CBG LMF)
chalkie666 Skype
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https://ifn.mpi-cbg.de  Biopolis Dresden Imaging Platform (BioDIP)
dan (at) chalkie.org.uk
( white (at) mpi-cbg.de )

[Prodanov Dimiter]

Hi Adam,

In general it is not possible to have such raw values. The 8bit is unsigned so you have values from 0 to 255. What you can calibrate the imge to the specified dynamic range and the. Use the calibrated values for further calculations.

Best regards,

Dimiter Prodanov

-----Original Message-----
From: Dr Adam Cliffe [mailto:[hidden email]]
Sent: Tuesday 27 September 2011 05:23
Subject: Converting 32-bit to 8 bit images

Hi Everyone,

I'm trying to do some spectral unmixing using Joachim Walter's Spectral Unmixing plugin. I can get it to work fine, and at the end it produces 2 32-bit stacks. My problem is converting these back to 8-bit images.  The 32-bit image has a range of -330.8  to +577.82. The range I'd like to keep in the 8-bit image is from say -40 to +353. (as seen by adjusting the max/min range.

I've tried setting this range, then hitting 'Apply' in the Brightness/contrast window. Whatever I do, when I convert to 8-bit, I get the same image as if I convert the original 32-bit image.

Can anyone tell me where I'm going wrong or offer any good advice for converting 32-bit to 8-bit?

thanks

Adam
 


Dr Adam Cliffe
Research Scientist, Rorth Lab

Institute of Molecular and Cell Biology
61 Biopolis Drive
Proteos
Singapore 138673

tel: [phone]

[Antoinette]

Hi, can anyone give me the detailed tutorial on how to convert image from 36 bit to 8bit?  My Visual .NET image converter just do the conversion from image to image and image to document.