Interpolation and extrapolation
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Interpolation is a technique used in image resizing, zooming, shrinking, rotating, and geometric corrections. It works by using known pixel data to estimate values at unknown points. There are different types of interpolation including nearest neighbor, bilinear, and bicubic. Nearest neighbor considers only the closest pixel, while bilinear takes the average of the closest 2x2 pixels. Bicubic interpolation provides the sharpest results as it averages over the closest 4x4 pixels.
Interpolation and extrapolation
- 2. INTERPOLATION • Used in • Zooming • Shrinking • Rotating • Geometric corrections 9/19/2014 brainbitz 2
- 3. Concept • Interpolation works by using known data to estimate values at unknown points. 9/19/2014 brainbitz 3
- 4. IMAGE RESIZE EXAMPLE NO INTERPOLATION 9/19/2014 brainbitz 4
- 5. WITH INTERPOLATION 9/19/2014 brainbitz 5
- 6. TYPES OF INTERPOLATION • Adaptive -It change depending on what they are interpolating (sharp edges vs. smooth texture) • Non adaptive – It treat all pixels equally. – Nearest neighbor algorithm – Bilinear algorithm – Bicubic algorithm 9/19/2014 brainbitz 6
- 7. Nearest neighbour interpolation • The output pixel is assigned the value of the pixel that the point falls within • No other pixels are considered. • It only considers one pixel — the closest one to the interpolated point. • Requires the least processing time of all the interpolation algorithms • This has the effect of simply making each pixel bigger. 9/19/2014 brainbitz 7
- 8. BILINEAR INTERPOLATION • The output pixel value is a weighted average of pixels in the nearest 2-by-2 neighborhood • Considers the closest 2x2 neighborhood of known pixel values surrounding the unknown pixel • It then takes a weighted average of these 4 pixels to arrive at its final interpolated value. • This results in much smoother looking images than nearest neighbor. 9/19/2014 brainbitz 8
- 10. BICUBIC INTERPOLATION • The output pixel value is a weighted average of pixels in the nearest 4-by-4 neighborhood • Bicubic produces noticeably sharper images than the previous two methods, and is perhaps the ideal combination of processing time and output quality. 9/19/2014 brainbitz 10