http://imagej.273.s1.nabble.com/Specific-color-channel-to-retrieve-from-an-image-in-a-plugin-tp5004950p5005068.html
brightness etc comment. The perils of copy and paste.
more modern processor with multiple cores. this only gives substantial
> Hi,
> getPixelValue is not particularly fast. The fastest way of going
> through an image pixel by pixel is using the 1-dimensional array
> access methods.
>
> Here is a code snippet:
>
> int[] colPixels = (int[]) ip.getPixels();
> PixelCount = ip.getPixelCount();
>
> for (int x = 0; x < PixelCount; x++) {
> //get brightness from shading image
> int pixVal = colPixels [x];
> //get red , green and blue values from pixVal
> int redVal = (pixVal & 0xff0000) >> 16;
> int greenVal = (pixVal & 0x00ff00) >> 8;
> int blueVal = (pixVal & 0x0000ff);
>
> if (blueVal <redVal &&blueVal <greenVal )
> blueVal =0;
> }
> }
>
> Hope this helps,
>
> Rob
>
>
>
> On 07/10/2013 11:26, Herbie wrote:
>> Philippe,
>>
>> you say you need to inspect every pixel of your image and that this
>> is slow.
>>
>> Sorry, but I don't think it is slow but it simply takes time,
>> especially if your images are big. Don't you agree?
>>
>> If you do the loop over all pixels in Java, I see little chance to
>> speed up the desired process.
>>
>> Best
>>
>> Herbie
>> _________________________________________
>> On 07.10.13 10:16, Philippe GENDRE wrote:
>>> Dear List,
>>>
>>> Recently, I posted a question to this list to retrieve a specific color
>>> channel (the red one for example) from a RGB image. The answer
>>> (ImageProcessor red = ((ColorProcessor)ip).getChannel(1, null);) is
>>> perfect
>>> but I have realized that it is not what I need. In fact I need to
>>> retrieve
>>> a specific color of pixel for example the blue ones and not the
>>> intensity
>>> of the channel. According to that I wrote the following code:
>>> ImageProcessor ipR=((ColorProcessor)ip).getChannel(1,null);
>>> ImageProcessor ipG=((ColorProcessor)ip).getChannel(2,null);
>>> ImageProcessor ipB=((ColorProcessor)ip).getChannel(3,null);
>>>
>>> for (int x=0; x<frame_width; x++){
>>> for (int y=0; y<frame_height; y++){
>>> if
>>> (ipB.getPixelValue(x,y)<ipR.getPixelValue(x,y)&&ipB.getPixelValue(x,y)<ipG.getPixelValue(x,y))
>>>
>>> ipB.set(x,y,0);
>>> }
>>> }
>>> That sounds good but slow. How to speed up this ?
>>>
>>> Best regards,
>>>
>>> Philippe
>>>
>>>
>>> 2013/9/26 Philippe GENDRE <
[hidden email]>
>>>
>>>> ImageProcessor red = ((ColorProcessor)ip).getChannel(1, null) is
>>>> exactly
>>>> what I needed.
>>>>
>>>> This list is a marvel. Thanks a lot.
>>>>
>>>> Philippe
>>>>
>>>>
>>>> 2013/9/26 Rasband, Wayne (NIH/NIMH) [E] <
[hidden email]>
>>>>
>>>> On Sep 26, 2013, at 1:02 PM, Philippe GENDRE wrote:
>>>>>
>>>>>> Dear List,
>>>>>>
>>>>>> I need to retrieve the red channel of an RGB image plus object as an
>>>>> image
>>>>>> processor in a plugin.
>>>>>>
>>>>>> What is the best solution ?
>>>>>
>>>>> Use the ImageProcessor.getChannel() method. Here is a JavaScript
>>>>> example:
>>>>>
>>>>> imp = IJ.openImage("
http://imagej.nih.gov/ij/images/clown.jpg");
>>>>> ip = imp.getProcessor();
>>>>> red = ip.getChannel(1, null);
>>>>> new ImagePlus("Red Channel", red).show();
>>>>>
>>>>> In a plugin, it would look like this:
>>>>>
>>>>> ImagePlus imp = IJ.openImage("
>>>>>
http://imagej.nih.gov/ij/images/clown.jpg");
>>>>> ImageProcessor ip = imp.getProcessor();
>>>>> ImageProcessor red = ((ColorProcessor)ip).getChannel(1, null);
>>>>> new ImagePlus("Red Channel", red).show();
>>>>>
>>>>> -wayne
>>>>>
>>>>> --
>>>>> ImageJ mailing list:
http://imagej.nih.gov/ij/list.html>>>>>
>>>>
>>>>
>>>
>>> --
>>> ImageJ mailing list:
http://imagej.nih.gov/ij/list.html>>>
>>
>> --
>> ImageJ mailing list:
http://imagej.nih.gov/ij/list.html>>
>
Dr. Rob van 't Hof