Stretchability-aware block scaling for image retargeting

• We propose a stretchability-aware block scaling approach to image retargeting.
• Image stretchability is evaluated based on gradient, saliency and color features.
• Stretchable space is proposed to determine the optimal size of the stretched image.
• Stretchability analysis is used to partition blocks and calculate scaling factors.
• An overall better retargeting performance of our approach is demonstrated.

This paper proposes an efficient approach to retarget images based on stretchability-aware block scaling. The image stretchability is first evaluated based on gradient, saliency and color features, and is used to generate the stretchable space. Then the optimal size of the stretched image is determined under the constraint of stretchable space and the same aspect ratio as the target image. Based on the analysis of image stretchability measures, the original image is partitioned into non-stretchable blocks and stretchable blocks, and their scaling factors are calculated based on their stretchability measures and the stretched image size, in order to possibly preserve non-stretchable blocks without distortion and reasonably resize stretchable blocks. Finally, the stretched image is uniformly scaled to generate the target image. Experimental results on a variety of images and the user study demonstrate that our approach achieves an overall better retargeting performance compared to the state-of-the-art image retargeting approaches.