What is Android Smartphone’s Camera Interpolation?

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Definition of Camera Interpolation?

All modern smartphones have integral cameras, that allow you to zoom in your images using special algorithms. In mathematics, interpolation is a method of calculation of intermediate value of numbers ​​using the available set of discrete parameters.

Interpolation has similar effect as a Screen Magnifier. In fact, Smartphone Software does not increase the sharpness and clarity of the image. It just extends the image to the desired size. Some smartphone manufacturers indicate in the product description on the package, that integrated camera has a resolution “up to 21 megapixels”. Most likely, the mentioned information refers to interpolation of image, that has a poor quality.

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Types of interpolation

Nearest-neighbor interpolation method

This is commonly used (basic) method of interpolation and it belongs to the category of the simplest algorithms. According to this method, pixel parameters shall be determined based on the parameters of one nearest point. As a result of mathematical calculations, it makes possible to double the size of each pixel. Using of the nearest pixel method of interpolation does not require large computing powers.

Bilinear interpolation

The value of each pixel shall be determined based on the parameters of four nearest points, fixed by camera. The result of the calculations becomes weighted average value of 4 pixels, surrounding the starting point. Bilinear interpolation allows to smooth out the color boundaries transitions of the objects. Obtained by this method images have much better quality and sharpness, comparing to images interpolated by the nearest pixel method.

Interpolation, camera, Android, smartphone, what is

Bicubic interpolation

The value of initial point shall be determined based on the parameters of sixteen nearest points. The closest points have a prevalent value in the calculation process. Software of modern smartphones frequently uses bicubic interpolation method, because it helps to achieve a high-quality image. Using of such a method requires significant CPU power and high resolution of integrated camera.

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Not to ask any questions:

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Pros and Cons

In Science Fiction movies many episodes show how camera captures the image of a passer-by and transmits digital information to a computer. Computer enlarges this image, recognizes the face and identify the person using a database. In reality, interpolation can’t add new details to the image. It just enlarges the original image with help of mathematical algorithm, improving its quality to an acceptable level.

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Disadvantages of interpolation

The most common defects, that occur in image scaling are:

  • Aliasing;
  • Blurring;
  • Halo effect.

All interpolation methods allow to keep a certain balance of all mentioned defects. For example, reducing of aliasing effect will lead to an increase of blurring and halo effect. Increasing of sharpness of the image will lead to blurriness and etc. In addition to mentioned defects, interpolation can cause various graphic “noises”, becoming visible at maximum zooming of the image. In this case “random” pixels and not relevant to the subject textures may appear on the image.

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