Composite Function for difference btw images

[Pranjal]

Hello all,

I was able to solve the difference problem using pixel level values in C++, but after Anthony mentioned use of composite command for the same, I've been trying to figure out how I could do that in C++. I've tried the following :

Code: Select all

 backframe.composite(inframe,0,0,DifferenceCompositeOp);

But this places the difference btw backframe and inframe over backframe. I was looking at getting just the difference into a new image. Is there a way around this?

Thanks
Pranjal

[anthony]

Make a clone of the original (backframe) image first.

[Pranjal]

Hi Anthony,

Thanks for that quick reply. Like you said, I tried making a clone of the backframe image. I was not able to do it using CloneImage(), so I instead copied the pixels of backframe into an image called cloneback. But how do I proceed from there?

Thanks again,
Pranjal

[anthony]

Now use the clone instead of the original for the composite.

[Pranjal]

Hi again,

Sorry to keep returning wih the same question again. But after cloning and using the new image, I still seem to get the esults into this new image. All I want is the difference between two images and the results as a new image by itself. The composite function seems to overwrite on the exsisting image pixels. I'm doing something wrong, and am not able to figure what.

Please help.
Thanks,
Pranjal

[anthony]

the composite function will always overwrite the destination image, that is is job.
If you want to keep the original destination image, you have two choices, either make a clone of that image, or read/create that image again.

[Pranjal]

Hi again,

I've tried the following -

Code: Select all

      Image inframe;
      inframe.read("image1.jpg");
      inframe.type(GrayscaleType);
      Image incopy = inframe;
            
      inframe.display();
      inframe.composite(incopy,0,0,DifferenceCompositeOp);
      inframe.display();

The result shows the original "image1.jpg". I was hoping it would be a "blank" image as the difference is "0". If that's not what Composite does, could you please tell me what will.

Please help.

Thanks,
-Pranjal

[anthony]

That is not a clone. You need to call CloneImage

Something like...
incopy = CloneImage(inframe);

I can't be certain as I don't use Magick++

[Pranjal]

Thanks for that quick reply. Looks like Magick++ doesn't recognize CloneImage(). I've even tried the following -

Code: Select all

      Image inframe;
      Image backframe;
      inframe.read("image1.jpg");
      backframe.read("background.jpg");
      
      inframe.quantizeColorSpace(GRAYColorspace);
      backframe.quantizeColorSpace(GRAYColorspace);
      inframe.quantizeColors(2);
      backframe.quantizeColors(2);
      inframe.quantizeDither(false);
      backframe.quantizeDither(false);

      inframe.display();
      backframe.display();

And nothing seems to change in the images.(??!!)

-Pranjal

[anthony]

I'll have to leave this then. outside my expertise.

[Pranjal]

Hmm...

That's not good news for me...