Evaluation of and compensation for spatial noise of LCDs in medical applications

Fan, Jiahua; Roehrig, Hans; Sundareshan, Malur K.; Krupiński, Elizabeth A.; Dallas, William J.; Gandhi, Kunal

doi:10.1118/1.1855031

Cited by 18 publications

(22 citation statements)

References 7 publications

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“…The remarkable higher resolution [1,2] than that is provided by the cathode ray tube (CRT) display is the most important feature of the LCDs. However, their noise properties seemed not to be good, as described in recent papers [2][3][4]. Moreover, the method of evaluation of the noise property is not welldefined because of problems in the treatment of signal components generated from discrete and complicated pixel structures.…”

Section: Introductionmentioning

confidence: 91%

“…Recent researchers employed common measurement procedures for the NPS measurement of LCDs, in which LCD images were captured digitally by cameras with charge-coupled devices (CCD), and a two-dimensional (2D) fast Fourier transform (FFT) was used [2][3][4]. In addition, pixel-aligned numerical apertures (PAs) that average the CCD data within the area corresponding to one LCD pixel were commonly applied for evaluation of the noise property, which was separated into inter-and intrapixel variations.…”

Section: Introductionmentioning

confidence: 99%

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Analysis method of noise power spectrum for medical monochrome liquid crystal displays

Ichikawa

Kodera

Nishimura

et al. 2008

Radiol Phys Technol

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We investigated methods of analyzing the noise power spectrum (NPS) measurement for medical liquid crystal displays (LCDs). Uniform images displayed on the LCDs were imaged with a high-performance digital camera equipped with a close-up lens, and then the NPSs were calculated from the image data by means of several analysis methods. In a method using the 2D fast Fourier transform (FFT) with a 256 x 256 pixels data segment (basic method), we examined the efficacy of a background trend correction (BTC) and a Hanning windowing process used for reducing the spectral estimation errors in the Fourier analysis. To improve the frequency resolution of the basic method, we examined two 2D FFT methods by using 512 x 512 and 1024 x 1024 pixel segments. In addition, we studied a 1D FFT method with 1024-point 1D noise profiles (1D method). In these three methods, the BTC by a second-order polynomial fit and Hanning windowing were commonly applied. A 3-mega-pixel (MP) and a 5-MP monochrome LCD were employed for evaluating the respective methods. Also, a prototype 5-MP LCD equipped with a new anti-reflection surface-coated panel was compared with the conventional 5-MP LCD. The Hanning windowing process was indispensable for avoiding the spectral leakage errors caused by the pixel structures of the LCD. Sufficient frequency resolution was obtained by the 2D FFT method with the 1024 x 1024 pixels segments and the 1D method. The method which provided the most reliable NPSs was the 1D method, with which the BTC was achieved successfully.

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Section: Introductionmentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

Analysis method of noise power spectrum for medical monochrome liquid crystal displays

Ichikawa

Kodera

Nishimura

et al. 2008

Radiol Phys Technol

View full text Add to dashboard Cite

show abstract

“…3,4,6), whereas works reported by others seem to conclude that FP performance is superior to that of CRT's. 5,7 A very detailed study of 32 different FPs described in Ref. 8 found that at optimized viewing conditions, the narrow viewing angles of the AMLCD displays need to be taken into account when changing from CRT to FPs.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Reading Conditions for Flat Panel Displays

Thomas

Chakrabarti²,

Kaczmarek³

et al. 2006

J Digit Imaging

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Task Group 18 (TG 18) of the American Association of Physicists in Medicine has developed guidelines for Assessment of Display Performance for Medical Imaging Systems. In this document, a method for determination of the maximum room lighting for displays is suggested. It is based on luminance measurements of a black target displayed on each display device at different room illuminance levels. Linear extrapolation of the above luminance measurements vs. room illuminance allows one to determine diffuse and specular reflection coefficients. TG 18 guidelines have established recommended maximum room lighting. It is based on the characterization of the display by its minimum and maximum luminance and the description of room by diffuse and specular coefficients. We carried out these luminance measurements for three selected displays to determine their optimum viewing conditions: one cathode ray tube and two flat panels. We found some problems with the application of the TG 18 guidelines to optimize viewing conditions for IBM T221 flat panels. Introduction of the requirement for minimum room illuminance allows a more accurate determination of the optimal viewing conditions (maximum and minimum room illuminance) for IBM flat panels. It also addresses the possible loss of contrast in medical images on flat panel displays because of the effect of nonlinearity in the dependence of luminance on room illuminance at low room lighting.

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“…The SHR-LCDs achieve a threefold higher-resolution than do current LCDs in only the sub-pixel direction [4,5,9,10]. Therefore, as the SHR-LCDs provide higher resolution only in the sub-pixel direction, it is necessary to carefully investigate their effectiveness for displaying digital mammograms.…”

Section: Introductionmentioning

confidence: 99%

Preliminary investigation of the clinical usefulness of super-high-resolution LCDs with 9 and 15 mega-sub-pixels: observation studies with phantoms

Nishimura

Ichikawa

Mochiya

et al. 2009

Radiol Phys Technol

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Our purpose in this study was to evaluate the preliminary clinical efficacy of soft-copy reading of digital mammography, for a 15-mega-sub-pixel (MsP) and a 9-MsP super-high-resolution liquid-crystal display (SHR-LCD) by use of an independent sub-pixel driving technology. We performed three kinds of phantom observation studies by six radiological technologists. Detectability of a contrast-detail phantom and simulated small objects (SSOs) resembling microcalcifications (MCLs), and shape discrimination ability of SSOs with round and square shapes, were examined and compared with a 5-MP conventional LCD (5-MP LCD). In each study, four types of display magnification ratio were used. The detectability and the shape discrimination ability of the 15-MsP SHR-LCD were highest among the three LCDs of most of the display magnification ratios. The 9-MsP SHR-LCD indicated a higher or equal performance as compared with the 5-MP LCD in the SSO detection and shape studies. The results of our study demonstrated that the SHR-LCDs had good potential to detect MCLs and to evaluate the shape in high-resolution digital mammography.

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Evaluation of and compensation for spatial noise of LCDs in medical applications

Cited by 18 publications

References 7 publications

Analysis method of noise power spectrum for medical monochrome liquid crystal displays

Analysis method of noise power spectrum for medical monochrome liquid crystal displays

Optimization of Reading Conditions for Flat Panel Displays

Preliminary investigation of the clinical usefulness of super-high-resolution LCDs with 9 and 15 mega-sub-pixels: observation studies with phantoms

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