Overall noise characteristics of reduced images on liquid crystal display and advantages of independent subpixel driving technology

• Published in: Medical physics (Lancaster) 2013-02, Vol.40 (2), p.021901-n/a
• Main Authors: Yamazaki, Asumi, Ichikawa, Katsuhiro, Kodera, Yoshie, Funahashi, Masao
• Format: Article
• Language: English
• Subjects: aliasing error; biomedical measurement; Cameras; Diagnostic Imaging - instrumentation; Digital computing or data processing equipment or methods, specially adapted for specific applications; Fourier Analysis; Image data processing or generation, in general; image denoising; Image enhancement or restoration, e.g. from bit‐mapped to bit‐mapped creating a similar image; image resolution; independent subpixel driving; Interpolation; Liquid crystal devices; liquid crystal display; liquid crystal displays; Liquid Crystals; magnification; Measuring for diagnostic purposes; Identification of persons; Medical image contrast; Medical image noise; medical image processing; Medical image spatial resolution; Medical imaging; Medical X‐ray imaging; Modulation transfer functions; Noise; noise measurement; noise power spectrum; Signal-To-Noise Ratio; Spatial resolution; X‐ray imaging
• ISSN: 0094-2405; 2473-4209
• DOI: 10.1118/1.4773031

Purpose: During soft-copy diagnoses, medical images with a large number of matrices often need to display reduced images on liquid crystal displays (LCDs) because of the spatial resolution limitation of LCDs. A new technology, known as independent subpixel driving (ISD), was recently applied to clinical uses aiming to improve the spatial resolution. The authors’ study demonstrates the overall noise characteristics of images displayed on a LCD at various display magnifications, with and without ISD application. Methods: Measurements of the overall noise power spectra (NPS) of x-ray images displayed on LCD were performed at varying display magnifications, with and without ISD. The NPS of displayed images in several display situations were also simulated based on hypothetical noise factors. Results: The measured and simulated NPS showed that noise characteristics worsened when the display magnification was reduced, due to aliasing errors. The overall noise characteristics were attributed to luminance-value fluctuation converted from pixel values, image-interpolation effects, inherent noise, and blurring of the LCD. ISD improved the noise characteristics because it suppressed noise increments by aliasing errors. Conclusions: ISD affected the noise-characteristic advantages of reduced images displayed on LCDs, particularly at low frequencies.