Image scaling is resizing a digital image while maintaining an aspect ratio. Scaling means both increasing and decreasing image resolution, upscaling and downscaling, respectively. It is widely used in computer graphics, video processing, in particular, it is implemented at the hardware level in TVs and video players.
A video scaler is a system that converts video signals from one screen resolution to another. Typically scalers are used to convert a signal from a lower resolution (e.g. 480p SD) to a higher resolution (e.g. 1080i HD).
Depending on the type of graphics (raster, vector), scaling is performed by different algorithms. Scaling vector images occurs without loss of image quality while increasing raster images, image quality may be lost: significant distortions in the geometry of small details and the appearance of false patterns on textures are possible. Therefore, when scaling raster images, specialized algorithms are used to smooth out unwanted effects.