Can we use a binary mask to embed a watermark in the roi?

Inorder to embed a watermark in roi of an image, can we create a mask and on obtaining it can we embed it.

Answer 1

[Walter Roberson]

Let I, R, W be binary. Then consider

I or (R and W)

[as825]

is it a complete code?

[Walter Roberson]

No, it is pseudo-code. You will need to think about what it does and then adopt the ideas into your MATLAB code.

[as825]

is there any way to embed the watermark into the roi without mask?

[Walter Roberson]

Yes, if you have a way of defining the ROI that does not involve selecting pixel-by-pixel through a mask.

[Image Analyst]

akila: mask and ROI are often used interchangeably. Both are "maps" of where to process the image and where not to touch the image. How are you defining them? What's the difference?

[Walter Roberson]

ROI can be in abstract form, whereas mask is almost always in binary form.

[Image Analyst]

I don't know what abstract form is. I'm envisioning either a list of x,y coordinates, or a logical image. In my work, either ROI or mask could be either form. ROIs are often simple shapes (boxes, circles) that are sometimes manually specified, though they don't have to be (they can have weird shapes). Masks can also be that, or they could be automatically generated irregularly shaped things, like you might get from thresholding. I don't think there's any general hard and fast definition but some people may have their own definitions. So I still don't know what akila means by "into the roi without mask".

[Walter Roberson]

For example specifying a center and a radius of a circle is an abstraction compared to specifying on a pixel-by-pixel basis whether the pixel is in the ROI or not. But ultimately for any given pixel there must be a decision procedure to decide whether it is in the ROI or not, but that decision procedure does not have to be in the form of a logical matrix.

Answer 2

[Image Analyst]

See my demo, attached below.

[as825]

the code that you ve provided is for the whole image. how can we use the fcode to embed only in the roi

[Walter Roberson]

find() the locations of the parts of the matrix that are within the roi. Then, when you are considering the K'th bit to be written, store it into the matrix indexed at the K'th location found.

[as825]

i ve used a circular roi. now i need to embed a image into it how is that possible

[Image Analyst]

It was meant for you to adapt, which it looks like you've done. To embed a circular portion of one gray scale image, defined by a binary image mask, into a different grayscale image, do this:

outputImage(binaryImage) = inputImage(binaryImage);

[as825]

I ve the roi circle's X coordinate, Y coordinate and radius of circle. How can I embed watermark with these values?

[Image Analyst]

Use poly2mask() to turn those coordinates into a binary image.

binaryImage = poly2mask(x, y, rows, columns);

Then use the code I gave you above.

outputImage(binaryImage) = inputImage(binaryImage);

[Walter Roberson]

The non-mask way of doing it would be to use inpoly() on a vectorized approximation of the outline of the circle.