In diagnostic radiology, most diagnostic images are presented in black and white. The ability of a medical display to present subtle grayscale gradations between black and white is therefore crucial. The more detail a physician can discern, the more accurate their diagnosis becomes. In order to standardize black and white imaging across medical displays, part 14 of the DICOM standard (PS3.14) has specified the Grayscale Standard Display Function (GSDF). It is widely used in radiology, cardiology, ophthalmology, dentistry, and radiotherapy imaging systems like X-ray, CT, MRI, and ultrasound equipment.

To ensure consistent standards for the image format and data quality of medical displays used in clinical diagnosis, the GSDF specifies the relationship between luminance and JND (Just Noticeable Difference). Human perception of brightness intensity follows a non-linear curve. At higher brightness levels, the human eye is less sensitive to changes in luminance than at lower brightness levels. Therefore, to make black-and-white details more pronounced, GSDF uses a grayscale distribution that is different from the Gamma 2.2 standard commonly used in commercial displays:

   
                                                                         ▲Gamma 2.2 vs. GSDF

In GSDF mode, the display characteristics of grayscale images are altered to make details in black-and-white images easier to distinguish:

Chroma ATE has recently launched the Chroma 71241 High-Precision Universal Measurement Probe, as well as the Chroma 71242 Small Size Measurement Probe (with a 10mm measurement aperture) for precise measurement of small display devices. Both are equipped with a GSDF measurement mode, allowing users to measure and calculate luminance change per step (dL/L), set upper and lower tolerance limits for each luminance level, plot GSDF curves, and calculate deviation percentages. The results are displayed in green and red indicators to easily confirm Pass/Fail status.

Chroma provides a complete optical inspection solution for medical displays. The Chroma 71241 High-Precision Universal Measurement Probe and 71242 Small Size Measurement Probe can be paired with the Chroma 2238 Video Pattern Generator, which features a built-in test pattern based on the DICOM PS3.14 grayscale standard. This setup enables measurement of a displayˈs grayscale, luminance, color, and color depth (10/12-bit).  

Developed using advanced digital signal processors and optoelectronic conversion technologies, the optical system includes components such as a condenser lens, automatic calibration shutter, light homogenization module, high-sensitivity detection device, object-side telecentric optical system, and a 20-bit analog-to-digital converter.  

Together with the Color Analysis Master software, the system provides complete analysis and control functionality including optical color measurement, Gamma measurement, GSDF measurement, flicker measurement, Delta E measurement, color gamut measurement, color calibration, and test sequence editing. Measurement data can be conveniently saved as text reports. 

For more information, please visit our official website and leave your requirements and contact information. We are happy to be of service.