Optimized Scale-and-Stretch for Image Resizing

Yu-Shuen Wang¹, Chiew-Lan Tai², Olga Sorkine³, Tong-Yee Lee¹

ACM Transaction on Graphics (Proceedings of SIGGRAPH 2008 Asia) Vol. 27, No.5, Dec 2008

¹National Cheng Kung University, Taiwan

²Hong Kong University of Science & Technology

³New York University

We partition the original image (left) into a grid mesh and deform it to fit the new desired dimensions (right), such that the quad faces covering important image regions are optimized to scale uniformly while regions with homogeneous content are allowed to be distorted. The scaling and stretching of the image content is guided by a significance map which combines the gradient and the saliency maps

　

Abstract	We present a “scale-and-stretch” warping method that allows resizing images into arbitrary aspect ratios while preserving visually prominent features. The method operates by iteratively computing optimal local scaling factors for each local region and updating a warped image that matches these scaling factors as closely as possible. The amount of deformation of the image content is guided by a significance map that characterizes the visual attractiveness of each pixel; this significance map is computed automatically using a novel combination of gradient and salience-based measures. Our technique allows diverting the distortion due to resizing to image regions with homogeneous content, such that the impact on perceptually important features is minimized. Unlike previous approaches, our method distributes the distortion in all spatial directions, even when the resizing operation is only applied horizontally or vertically, thus fully utilizing the available homogeneous regions to absorb the distortion. We develop an efficient formulation for the nonlinear optimization involved in the warping function computation, allowing interactive image resizing.
Paper
supplemental Results
Video	Video.mp4
Bibtex	@ARTICLE{Wang:2008,      author = {Yu-Shuen Wang, Chiew-Lan Tai, Olga Sorkine and Tong-Yee Lee},      title = { Optimized Scale-and-Stretch for Image Resizing},      journal = {ACM Trans. Graph. (Proceedings of ACM SIGGRAPH ASIA},      year = {2008},      volume = {27},      number = {5},   }
Acknowledgement	We thank the anonymous reviewers for their valuable comments. We are grateful to Daniel Cohen-Or for the insightful discussions, and to Ariel Shamir and Michael Rubinstein for providing the seam carving comparisons. We also thank Oscar Kin-Chung Au for the discussion on algorithms and Michael Brown for providing the video voice over. The following flickr members have kindly allowed us to use their images: stuckincustoms (car, deck, child, tomb and San Francisco heart), darwinbell (fruit), meantux (girl in front of wall), almarmon1 (buildings), millzero (surfer), wolfgangstaudt (forecourt, bower, church, Japanese house, river course and street), edbrambley (woman in room), charlesfred (walking people), crushedredpepper (old man and girl), cuellar (castle), minebeyaz (canal house), extranoise (upward sky and brick house), ikytrkr (lotus), wili (boys), tookie (jumping girls), marko k(fish), yanivba (courtyard), shawnhenning (cat), booleansplit (Eiffel Tower), betsyjean79 (doll) and Jstar (biker). This work is supported in part by the Landmark Program of the National Cheng-Kung University Top University Project (Contract B0008), the National Science Council (Contracts NSC-95-2221-E-006-193-MY2, NSC-96-2628-E-006-200-MY3 and NSC-97-2628-E-006-125-MY3), Taiwan,Republic of China and the Research Grant Council of the Hong Kong Special Administrative Region, China (Project No: 620107).