Adaptive sharpening of photos

Ilia V. Safonov, Michael N. Rychagov, Ki Min Kang, Sang Ho Kim

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

17 Scopus citations

Abstract

Sharpness is an important attribute that contributes to the overall impression of printed photo quality. Often it is impossible to estimate sharpness prior to printing. Sometimes it is a complex task for a consumer to obtain accurate sharpening results by editing a photo on a computer. The novel method of adaptive sharpening aimed for photo printers is proposed. Our approach includes 3 key techniques: sharpness level estimation, local tone mapping and boosting of local contrast. Non-reference automatic sharpness level estimation is based on analysis of variations of edges histograms, where edges are produced by high-pass filters with various kernel sizes, array of integrals of logarithm of edges histograms characterizes photo sharpness, machine learning is applied to choose optimal parameters for given printing size and resolution. Local tone mapping with ordering is applied to decrease edge transition slope length without noticeable artifacts and with some noise suppression. Unsharp mask via bilateral filter is applied for boosting of local contrast. This stage does not produce strong halo artifact which is typical for the traditional unsharp mask filter. The quality of proposed approach is evaluated by surveying observer's opinions. According to obtained replies the proposed method enhances the majority of photos.

Original languageEnglish
Title of host publicationProceedings of SPIE-IS and T Electronic Imaging - Color Imaging XIII
Subtitle of host publicationProcessing, Hardcopy, and Applications
DOIs
StatePublished - 2008
Externally publishedYes
EventColor Imaging XIII: Processing, Hardcopy, and Applications - San Jose, CA, United States
Duration: Jan 29 2008Jan 31 2008

Publication series

NameProceedings of SPIE - The International Society for Optical Engineering
Volume6807
ISSN (Print)0277-786X

Conference

ConferenceColor Imaging XIII: Processing, Hardcopy, and Applications
Country/TerritoryUnited States
CitySan Jose, CA
Period01/29/0801/31/08

Keywords

  • Local tone mapping
  • Non-reference sharpness estimation
  • Sharpening
  • Subjective tests

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