The Czenakowski distance (sometimes shortened as CZD) is a per-pixel quality metric that estimates quality or similarity by measuring differences between pixels. Because it compares vectors with strictly non-negative elements, it is often used to compare colored images, as color values cannot be negative. This different approach has a better correlation with subjective quality assessment than PSNR.[citation needed]

Definition

edit

Androutsos et al. give the Czenakowski coefficient as follows:[1]

 

Where a pixel   is being compared to a pixel   on the k-th band of color – usually one for each of red, green and blue.

For a pixel matrix of size  , the Czenakowski coefficient can be used in an arithmetic mean spanning all pixels to calculate the Czenakowski distance as follows:[2][3]

 

Where   is the (i, j)-th pixel of the k-th band of a color image and, similarly,   is the pixel that it is being compared to.

Uses

edit

In the context of image forensics – for example, detecting if an image has been manipulated –, Rocha et al. report the Czenakowski distance is a popular choice for Color Filter Array (CFA) identification.[2]

References

edit
  1. ^ Androutsos, D.; Plataniotiss, K.N.; Venetsanopoulos, A.N. (1998). "Distance measures for color image retrieval". Proceedings 1998 International Conference on Image Processing. ICIP98 (Cat. No.98CB36269). Vol. 2. pp. 770–774. doi:10.1109/ICIP.1998.723652. ISBN 0-8186-8821-1. S2CID 10134889.  
  2. ^ a b Rocha, Anderson; Scheirer, Walter; Boult, Terrance; Goldenstein, Siome (October 2011). "Vision of the unseen". ACM Computing Surveys. 43 (4): 1–42. doi:10.1145/1978802.1978805. ISSN 0360-0300. S2CID 113533.  
  3. ^ Kale, K. V.; Mehrotra, S. C.; R. R. Manza, R. R., eds. (2007). Advances in Computer Vision and Information Technology. New Delhi, India: I.K. International Pvt. Ltd. p. 91. ISBN 978-81-89866-74-7.