High Pass Filtering: Get It & Sharpen Image

[nao113]

Homework Statement

You studied that the delay-and-sum results in low-pass filtering of signal.
How can you realize high-pass filter function using similar processing?

Did I answer them correctly?

Relevant Equations

Theory

How can we get high pass filter? When we apply a low-pass filter to 𝑥 resulting in 𝑦 , then 𝑥−𝑦 should contain whatever is left over, this gives us a high-pass filter. In image processing, high-pass filter will increase the contrast between bright and dark pixel to produce a sharpen image.

 

[Baluncore]

You are correct about the subtraction.
But your comment on increased contrast is not needed.
A high-pass filter will highlight the edges of objects, but large areas of blacks and whites will become grey, which is not an increase of contrast. To get an increase in contrast, you must amplify the signal.

 

[nao113]

You are correct about the subtraction.
But your comment on increased contrast is not needed.
A high-pass filter will highlight the edges of objects, but large areas of blacks and whites will become grey, which is not an increase of contrast. To get an increase in contrast, you must amplify the signal.

so, I only need to answer like this `How can we get high pass filter? When we apply a low-pass filter to 𝑥 resulting in 𝑦 , then 𝑥−𝑦 should contain whatever is left over, this gives us a high-pass filter.` right?

 

[nao113]

You are correct about the subtraction.
But your comment on increased contrast is not needed.
A high-pass filter will highlight the edges of objects, but large areas of blacks and whites will become grey, which is not an increase of contrast. To get an increase in contrast, you must amplify the signal.

And what does it mean by similar processing?

 

[Baluncore]

And what does it mean by similar processing?

Using one delay element, and one arithmetic sum or difference.

 

[nao113]

Using one delay element, and one arithmetic sum or difference.

how can I realize High Pass filtering through that process? I think my answer doesn't cover the question.

 

[Baluncore]

You studied that the delay-and-sum results in low-pass filtering of signal.
How can you realize high-pass filter function using similar processing?

The delay and sum for low-pass is the clue.
For high-pass, you use delay and subtract.

 

[nao113]

The delay and sum for low-pass is the clue.
For high-pass, you use delay and subtract.

is there any reference for delay and subtract for high pass?

The delay and sum for low-pass is the clue.
For high-pass, you use delay and subtract.

Thank you very much for the explanation

 

[berkeman]

Homework Statement:: You studied that the delay-and-sum results in low-pass filtering of signal.
How can you realize high-pass filter function using similar processing?

Did I answer them correctly?
Relevant Equations:: Theory

How can we get high pass filter? When we apply a low-pass filter to 𝑥 resulting in 𝑦 , then 𝑥−𝑦 should contain whatever is left over, this gives us a high-pass filter. In image processing, high-pass filter will increase the contrast between bright and dark pixel to produce a sharpen image.

Sorry, are you asking in the context of analog or digital filters? I'm getting the impression that your question is about digital filters, but some of your comments don't make sense to me if so.

is there any reference for delay and subtract for high pass?

If this is a question for digital filters, what learning resources have you used so far?