Effect Of Quantization On Digitized Noise And Detection Of Low-Contrast Objects

Maryellen Lissak Giger; Ken Ohara; Kunio Doi

doi:10.1117/12.975396

12 June 1986 Effect Of Quantization On Digitized Noise And Detection Of Low-Contrast Objects

Maryellen Lissak Giger, Ken Ohara, Kunio Doi

Proceedings Volume 0626, Application of Optical Instrumentation in Medicine XIV and Picture Archiving and Communication Systems; (1986) https://doi.org/10.1117/12.975396
Event: Application of Optical Instrumentation in Medicine XIV and Picture Archiving and Communication Systems (PACS IV) for Medical Applications, 1986, Newport Beach, CA, United States

Abstract

We investigated the effect of quantization on the signal contrast, noise, and signal-to-noise ratio at three stages of the digital imaging chain, namely, acquisition, processing and display. Histogram analysis was performed for simple objects of constant magnitude superimposed on a uniform noisy background. After quantization, physical quantities, such as the signal contrast, noise and SNR, will vary depending on the fractional displacement of the quantization bin relative to the analog values. These physical quantities on average can provide information on the effectivenesss of a given A/D converter. As the rms value of the analog noise decreases, the various physical quantities become more sensitive to the effect of quantization. On average, the rms noise value after quantization will gradually increase as the quantization increment increases. The average SNR after quantization decreases initially as the quantization increment increases and then it misleadingly increases relative to the SNR prior to quantization. As quantization or further bit reduction becomes coarser, the noise Wiener spectrum will on average increase, and this increase will become relatively larger when the original noise data are obtained with higher x-ray exposures or larger sampling apertures. Image processing techniques allow for the potential increase in the number of bits in the image. However, the conventional CRT monitor is capable of only displaying 256 grey levels. At the display stage, though, observers may be able to detect signals having a contrast of less than a single display grey level due to the capability of the noise to carry the signal. However, in some cases, the potential of various processing techniques may be limited by the display device.

Citation Download Citation

Maryellen Lissak Giger, Ken Ohara, and Kunio Doi "Effect Of Quantization On Digitized Noise And Detection Of Low-Contrast Objects", Proc. SPIE 0626, Application of Optical Instrumentation in Medicine XIV and Picture Archiving and Communication Systems, (12 June 1986); https://doi.org/10.1117/12.975396

ACCESS THE FULL ARTICLE

INSTITUTIONAL
Select your institution to access the SPIE Digital Library.

SELECT YOUR INSTITUTION

PERSONAL
Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.

PERSONAL SIGN IN

No SPIE Account? Create one

PURCHASE THIS CONTENT

SUBSCRIBE TO DIGITAL LIBRARY

50 downloads per 1-year subscription

Members: $195

Non-members: $335 ADD TO CART

25 downloads per 1 - year subscription

Members: $145

Non-members: $250 ADD TO CART

PURCHASE SINGLE ARTICLE

Includes PDF, HTML & Video, when available