Re: How to work with color images?

Posted by Juanjo Vega on May 26, 2011; 10:31am
URL: http://imagej.273.s1.nabble.com/How-to-work-with-color-images-tp3684447p3684449.html

Thanks guys!

I just discovered:

ImagePlus.getPixel(i, j): int[]

It returns RGB values as an int array, so you don't need to mask the pixel value.

I'm not sure, but I think it may be a good apporach when you need to access pixels here and there, but for processing entire images, I think the bitmasking method would be faster.

The "split channels" is ok, but I want to do it in background, not showing the splitted channels. It has more to do with my other message about how o avoid showing results when running stuff programmatically.

Sincerely,

Juanjo.

On May 25, 2011, at 8:30 PM, Curtis Rueden wrote:

> Hi Juan,
>
> So, do I have to convert every pixel like that before working with them? Is
>> there no API for RGB images? Maybe a method to split the image in three
>> different gray scale images and to merge them after being processed, would
>> be helpful.
>>
>
> There are many different ways of dealing with it. To split into three
> different grayscale images first, use a command such as:
>
>  IJ.run(imp, "Split Channels", "");
>
> (This is what the macro recorder produces when executing the command Image >
> Color > Split Channels.)
>
> But just using the bitmasking code you mentioned is fine too.
>
> Regards,
> Curtis
>
> On Wed, May 25, 2011 at 5:09 AM, Juanjo Vega <[hidden email]> wrote:
>
>> Hello everyone,
>>
>> I need to work with colour images in a plugin I'm developing, and as it is
>> my first time and I'm pretty confused.
>>
>> I had a look into the "Color Threshold" plugin and found this:
>>
>> int c, r, g, b;
>>
>> ...
>>
>> c=ip.getPixel(x,y);
>>
>> r = ((c&0xff0000)>>16);//R
>> g = ((c&0x00ff00)>>8);//G
>> b = ( c&0x0000ff); //B
>>
>> So, do I have to convert every pixel like that before working with them? Is
>> there no API for RGB images? Maybe a method to split the image in three
>> different gray scale images and to merge them after being processed, would
>> be helpful.
>>
>> Any help will he welcome, plugins, API reference, etc. :)
>>
>> Sincerely,
>>
>> Juanjo.
>>
>> ------------------------------------------------------------
>> Juanjo Vega ([hidden email])
>>
>> Unidad de Biocomputación. Laboratorio B-13.
>> Centro Nacional de Biotecnología. CNB-CSIC.
>> C\ Darwin, 3. Campus de Cantoblanco.
>> Universidad Autónoma de Madrid.
>> 28049, Madrid, Spain.
>>
>> http://www.cnb.csic.es
>> http://www.biocomp.cnb.csic.es
>>
>> [phone]
>>
>> "Las mejores almas son capaces de los mayores vicios como de las mayores
>> virtudes, y aquellos que caminan despacio por el camino recto pueden
>> llegar más lejos que los que corren pero se apartan de él." - Discurso
>> del Método, René Descartes.
>>

------------------------------------------------------------
Juanjo Vega ([hidden email])

Unidad de Biocomputación. Laboratorio B-13.
Centro Nacional de Biotecnología. CNB-CSIC.
C\ Darwin, 3. Campus de Cantoblanco.
Universidad Autónoma de Madrid.
28049, Madrid, Spain.

http://www.cnb.csic.es
http://www.biocomp.cnb.csic.es

[phone]

"Las mejores almas son capaces de los mayores vicios como de las mayores
virtudes, y aquellos que caminan despacio por el camino recto pueden
llegar más lejos que los que corren pero se apartan de él." - Discurso
del Método, René Descartes.