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Proceedings Paper

Method for measuring the objective quality of the TV-out function of mobile handsets
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Paper Abstract

Digital cameras, printers and displays have their own established methods to measure their performance. Different devices have their own special features and also different metrics and measuring methods. The real meaning of measuring data is often not learnt until hands-on experience is available. The goal of this study was to describe a preliminary method and metrics for measuring the objective image quality of the TV-out function of mobile handsets. The TV-out application was image browsing. Image quality is often measured in terms of color reproduction, noise and sharpness and these attributes were also applied in this study. The color reproduction attribute was studied with color depth, hue reproduction and color accuracy metrics. The noise attribute was studied with the SNR (signal to noise ratio) and chroma noise metrics. The sharpness attribute was studied with the SFR (spatial frequency response) and contrast modulation metrics. The measuring data was gathered by using a method which digitized the analog signal of the TV-out device with a frame grabber card. Based on the results, the quantization accuracy, chroma error and spatial reproduction of the signal were the three fundamental factors which most strongly affected the performance of the TV-out device. The quantization accuracy of the device affects the number of tones that can be reproduced in the image. The quantization accuracy also strongly affects the correctness of hue reproduction. According to the results, the color depth metric was a good indicator of quantization accuracy. The composite signal of TV-out devices transmits both chroma and luminance information in a single signal. A change in the luminance value can change the constant chroma value. Based on the results, the chroma noise metric was a good indicator for measuring this phenomenon. There were differences between the spatial reproductions of the devices studied. The contrast modulation was a clear metric for measuring these differences. The signal sharpening of some TV-out devices hindered the interpretation of SFR data.

Paper Details

Date Published: 19 January 2009
PDF: 12 pages
Proc. SPIE 7242, Image Quality and System Performance VI, 724212 (19 January 2009); doi: 10.1117/12.805425
Show Author Affiliations
Mikko Nuutinen, Helsinki Univ. of Technology (Finland)
Pirkko Oittinen, Helsinki Univ. of Technology (Finland)

Published in SPIE Proceedings Vol. 7242:
Image Quality and System Performance VI
Susan P. Farnand; Frans Gaykema, Editor(s)

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