Concept of projection in image processing

Hello, I am working on Image processing.Being new to this field , I don't know the concept of horizontal and vertical projection on an image. Can anyone please give a clear picture of projection in image processing as it would be very helpful for me to proceed forward.

Thanks in advance

Answer 1

[Image Analyst]

Do you mean just summing the image vertically and horizontally?

verticalProfile = sum(grayImage, 2);
horizontalProfile = sum(grayImage, 1);

[lotus whit]

could you please tell me , how calculate central and ring projection for binary image?

[Image Analyst]

Define what those are.

[lotus whit]

 Thank you for your response ,RP(ring projection)and CP(central projection) are
 methods for transforming 2-D pattern in to 1-D pattern , RP reduces the 
dimensionality by performing projection along circles with different  radius 
, while CP reduces the dimensionality by performing projection 
along lines with different polar angles.

[Image Analyst]

Sounds like radon() does what you call CP.