XXXX Analysis and Solution of CSS-Sprite Packing Problem
XXXX Analysis and Solution of CSS-Sprite Packing Problem JAKUB MARSZAŁKOWSKI, JAN MIZGAJSKI, DARIUSZ MOKWA and MACIEJ DROZDOWSKI, Institute of Computing Science, Poznan´ University of Technology A CSS-sprite packing problem is considered in this paper. CSS-sprite is a technique of combining many pictures of a web page into one image for the purpose of reducing network transfer time. CSS-sprite packing problem is formulated here as an optimization challenge. The significance of geometric packing, image compression and communication performance is discussed. A mathematical model for constructing multiple sprites and optimization of load time is proposed. The impact of PNG sprite aspect ratio on file size is studied experimentally. Benchmarking of real user web browsers communication performance covers latency, bandwidth, number of concurrent channels as well as speedup from parallel download. Existing software for building CSS-sprites is reviewed. A novel method, called Spritepack, is proposed and evaluated. Spritepack outperforms current software. CCS Concepts: Information systems ! Web interfaces; Computing methodologies ! Image com- pression; Networksr ! Network performance modeling; Mathematicsr of computing ! Combinatorial algorithms;r r General Terms: Algorithms, Experimentation, Performance Additional Key Words and Phrases: CSS image sprites, load time reduction, web optimization, heuristics, image compression, JPEG, PNG, rectangle packing, web engineering ACM Reference Format: Jakub Marszałkowski, Jan Mizgajski, Dariusz Mokwa and Maciej Drozdowski, 2014. A Challenge of CSS- Sprite Packing ACM Trans. Web V, N, Article XXXX ( 2015), 33 pages. DOI: http://dx.doi.org/10.1145/2818377 1. INTRODUCTION Short web page load time has a great importance for the Internet industry [Weinberg 2000; Marszałkowski et al. 2014].
[Show full text]