A smart device such as a television, tablet, and smartphone, often displays a compound image consisting of various types of sub-images, including texts and pictures. A text image displayed on a smart device is composed of red, green, and blue (RGB) sub-pixels having strong correlation among them. This paper proposes a new compression algorithm, called sub-pixel gradient compression (SPGC), that makes use of the correlation in a text in order to improve its compression efficiency. The initial step of the proposed algorithm converts a text into a de-colorized image in which RGB sub-pixels vary gradually. The de-colorization is a necessary step to further enhance the correlation among RGB sub-pixels, and thereby improving the compression efficiency. From the de-colorized text, the next step estimates the slopes of the gradual variations among sub-pixels and then encodes the slopes and their associated information as a bitstream. SPGC is a relatively simple algorithm because its main operation is the estimation of sub-pixel gradients and the precise estimation of the gradients makes it possible to reduce a degradation of the quality of the texts. Experimental results show that SPGC maintains lower complexity and a higher compression ratio than the compression standards including JPEG, JPEG-2000, H.264, or HEVC.
Bibliographical noteFunding Information:
Manuscript received April 1, 2018; accepted May 23, 2018. Date of publication June 1, 2018; date of current version June 28, 2018. This work was supported in part by the Samsung Electronics and the Korea Institute for Advancement of Technology Grant by the Korean Government (Ministry of Trade, Industry and Energy, HRD Program for Software-SoC Convergence) under Grant N0001883, and in part by the Institute for Information and Communications Technology Promotion Grant by the Korea Government (Development of Intelligent Semiconductor Technology for Vision Recognition Signal Processing for Vehicle Based on Multi-Sensor Fusion) under Grant 2017-0-00721. (Corresponding author: Hyuk-Jae Lee.) K. Kim is with Foundry Business, Samsung Electronics, Hwaseong 18373, South Korea (e-mail: firstname.lastname@example.org).
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All Science Journal Classification (ASJC) codes
- Media Technology
- Electrical and Electronic Engineering