## What is sparse representation in image processing?

Sparse approximation (also known as sparse representation) theory deals with sparse solutions for systems of linear equations. Techniques for finding these solutions and exploiting them in applications have found wide use in image processing, signal processing, machine learning, medical imaging, and more.

## What is compression in image processing?

Image compression is minimizing the size in bytes of a graphics file without degrading the quality of the image to an unacceptable level. The reduction in file size allows more images to be stored in a given amount of disk or memory space.

**Which transform is used for image compression?**

Discrete Cosine Transform (DCT) – The most widely used form of lossy compression. It is a type of Fourier-related transform, and was originally developed by Nasir Ahmed, T.

### Why is sparse represented?

Sparse representations are obtained in a basis that takes advantage of some form of regularity of the input signals, creating many small-amplitude coefficients. Audio signals, such as musical recordings, also have a complex geometric regularity in time-frequency dictionaries.

### Why and when do we use sparse representation?

Sparse representations of a signal are easier to describe because they’re short and highlight the essential features. This can be helpful if one wants to understand the signal, the process that generated it, or other systems that interact with it.

**What are the types of compression?**

There are two main types of compression: lossy and lossless.

#### What are compression techniques?

Compression techniques fall into two classes: lossless and lossy. Both are very common in use: an example of lossless compression is ZIP archive files and an example of lossy compression is JPEG image files.

#### Why do we need sparse coding?

If you try to find a vector space to plot a representation of your data, you need to find a basis of vectors. Given a number of dimensions, sparse coding tries to learn an over-complete basis to represent data efficiently. To do so, you must have provided at first enough dimensions to learn this over-complete basis.