convert uint16 image to uint8 image in ImageJ

[Marko Usaj]

Hello!

I have the following questions:

In what way is in app. ImageJ performs this task: convert uint16 to uint8
image? i am specially interesting in intensity rescaling from [0 65535] to
[0 255].

thank you!!

Marko

[Albert Cardona]

> In what way is in app. ImageJ performs this task: convert uint16 to uint8
> image? i am specially interesting in intensity rescaling from [0 65535] to
> [0 255].
>  


ImagePlus imp = IJ.getImage()
imp.setProcessor(null, imp.getProcessor().convertToByte(true));


The above is equivalent to the menu command:  Image / type / 8-bit
which you can run as:

IJ.run("8-bit");


--
Albert Cardona
http://www.mcdb.ucla.edu/Research/Hartenstein/acardona

[Marko Usaj]

Thank you for you replay...

Have you already also now the algorithm which perform that?

Probably 16BPP intensity value is Divided by 65535 and then multiplied
by 255...and the is performing some rounding the number...in what way?
Floor? Near neighbor?...etc.  

Thank you!

Marko
-----Original Message-----
From: ImageJ Interest Group [mailto:[hidden email]] On Behalf Of
Albert Cardona
Sent: 6. december 2007 1:41
To: [hidden email]
Subject: Re: convert uint16 image to uint8 image in ImageJ

> In what way is in app. ImageJ performs this task: convert uint16 to
uint8
> image? i am specially interesting in intensity rescaling from [0
65535] to
> [0 255].
>  


ImagePlus imp = IJ.getImage()
imp.setProcessor(null, imp.getProcessor().convertToByte(true));


The above is equivalent to the menu command:  Image / type / 8-bit
which you can run as:

IJ.run("8-bit");


--
Albert Cardona
http://www.mcdb.ucla.edu/Research/Hartenstein/acardona

[Joachim Wesner]

Hi there,

I am pretty sure there is actually no complicated magic involved, simply
bit shifting, which can be achieved like that (especially if you only want
to scale from 65536 to 256)

      pixels8[i] = (byte)((pixels16[i] & 0xffff) >> 8);

(Due to the shifting it makes no difference if you AND with 0xffff or
0xff00)

Look up the short sections on casting and simulating unsigned types in Java
in the Writing ImageJ Plugins Tutorial!!

http://mtd.fh-hagenberg.at/depot/imaging/imagej/tutorial171.pdf


Mit freundlichen Grüßen / Best regards

Joachim

Ernst Leitz Strasse 17-37 | 35578 Wetzlar (Germany)
Tel.  [phone] | Fax [phone]

____________________________________________

Leica Microsystems CMS GmbH | GmbH mit Sitz in Wetzlar | Amtsgericht
Wetzlar  HRB 2432
Geschäftsführer: Dr. Martin Haase | Colin Davis | Dr. Wolf-Otto Reuter


                                                                           
             Marko Usaj                                                    
             <[hidden email]                                            
             I-LJ.SI>                                                   An
             Gesendet von:              [hidden email]                
             ImageJ Interest                                         Kopie
             Group                                                        
             <[hidden email].                                       Thema
             GOV>                       Re: convert uint16 image to uint8  
                                        image in ImageJ                    
                                                                           
             06.12.2007 02:01                                              
                                                                           
                                                                           
              Bitte antworten                                              
                    an                                                    
              ImageJ Interest                                              
                   Group                                                  
             <[hidden email].                                            
                   GOV>                                                    
                                                                           
                                                                           




Thank you for you replay...

Have you already also now the algorithm which perform that?

Probably 16BPP intensity value is Divided by 65535 and then multiplied
by 255...and the is performing some rounding the number...in what way?
Floor? Near neighbor?...etc.

Thank you!

Marko
-----Original Message-----
From: ImageJ Interest Group [mailto:[hidden email]] On Behalf Of
Albert Cardona
Sent: 6. december 2007 1:41
To: [hidden email]
Subject: Re: convert uint16 image to uint8 image in ImageJ

> In what way is in app. ImageJ performs this task: convert uint16 to
uint8
> image? i am specially interesting in intensity rescaling from [0
65535] to
> [0 255].
>


ImagePlus imp = IJ.getImage()
imp.setProcessor(null, imp.getProcessor().convertToByte(true));


The above is equivalent to the menu command:  Image / type / 8-bit
which you can run as:

IJ.run("8-bit");


--
Albert Cardona
http://www.mcdb.ucla.edu/Research/Hartenstein/acardona



______________________________________________________________________
This email has been scanned by the MessageLabs Email Security System.
For more information please visit http://www.messagelabs.com/email 
______________________________________________________________________