Evaluation of 360° Image Projection Formats; Comparing Format Conversion Distortion Using Objective Quality Metrics

Currently available 360° cameras normally capture several images covering a scene in all directions around a shooting point. The captured images are spherical in nature and are mapped to a two-dimensional plane using various projection methods. Many projection formats have been proposed for 360° videos. However, standards for a quality assessment of 360° images are limited. In this paper, various projection formats are compared to explore the problem of distortion caused by a mapping operation, which has been a considerable challenge in recent approaches. The performances of various projection formats, including equi-rectangular, equal-area, cylindrical, cube-map, and their modified versions, are evaluated based on the conversion causing the least amount of distortion when the format is changed. The evaluation is conducted using sample images selected based on several attributes that determine the perceptual image quality. The evaluation results based on the objective quality metrics have proved that the hybrid equi-angular cube-map format is the most appropriate solution as a common format in 360° image services for where format conversions are frequently demanded. This study presents findings ranking these formats that are useful for identifying the best image format for a future standard.

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Benchmarking of objective quality metrics for HDR image quality assessment

EURASIP Journal on Image and Video Processing ◽

10.1186/s13640-015-0091-4 ◽

2015 ◽

Vol 2015 (1) ◽

Cited By ~ 48

Author(s):

Philippe Hanhart ◽

Marco V. Bernardo ◽

Manuela Pereira ◽

António M. G. Pinheiro ◽

Touradj Ebrahimi

Keyword(s):

Image Quality ◽

Quality Assessment ◽

Image Quality Assessment ◽

Quality Metrics ◽

Objective Quality ◽

Hdr Image

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Quality Assessment of 2.5D Prints Using 2D Image Quality Metrics

Applied Sciences ◽

10.3390/app11167470 ◽

2021 ◽

Vol 11 (16) ◽

pp. 7470

Author(s):

Altynay Kadyrova ◽

Vlado Kitanovski ◽

Marius Pedersen

Keyword(s):

Image Quality ◽

Quality Assessment ◽

Quality Metrics ◽

Reference Image ◽

Single Shot ◽

Current State ◽

Image Quality Metrics ◽

Objective Quality ◽

Multiple Shot ◽

Set Up

Quality assessment is an important aspect in a variety of application areas. In this work, the objective quality assessment of 2.5D prints was performed. The work is done on camera captures under both diffuse (single-shot) and directional (multiple-shot) illumination. Current state-of-the-art 2D full-reference image quality metrics were used to predict the quality of 2.5D prints. The results showed that the selected metrics can detect differences between the prints as well as between a print and its 2D reference image. Moreover, the metrics better detected differences in the multiple-shot set-up captures than in the single-shot set-up ones. Although the results are based on a limited number of images, they show existing metrics’ ability to work with 2.5D prints under limited conditions.

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