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How to Accurately Display Both Monochrome and Color Images with the Ideal Grayscale

As medical technology improves, hospitals are handling a wider range and volume of imaging data. This has led to combining the use of both monochrome and color images to maximize diagnostic accuracy. 


Monochrome and color images should ideally be displayed using separate grayscales. For monochrome images, the DICOM Part 14 Grayscale Standard Display Function (GSDF) is recommended, and for color Gamma 2.2 is recommended. Not using the appropriate grayscale may result in viewing a sub-par image, and potentially failing to notice diagnostic information. 



GSDF and Gamma 2.2 display images differently. When color images are viewed using GSDF, colors can be subdued and difficult to distinguish, however monochrome images are accurately displayed. When monochrome images are viewed using Gamma 2.2, contrast can be lost between shadows.

Some monitor technologies, such as EIZO’s CAL Switch function, allow the user to manually switch the monitor to preset modes that are designed for each type of modality. However when viewing both monochrome and color images together, many users find this time-consuming and tedious, and choose just to stick with GSDF.  This is where EIZO’s Hybrid Gamma PXL function comes into play.


Many medical monitors come with functions to switch the monitor to different modes, such as the EIZO CAL Switch function. 

The Hybrid Gamma PXL function analyzes each pixel of each image, distinguishes whether it is a color pixel or a grayscale pixel, and then calibrates the pixel to either GSDF, or a blend of GSDF and Gamma 2.2 – depending on the darkness of the color, all without any lag.  


When a color pixel is discovered, a combination of Gamma 2.2 and GSDF is used depending on the characteristics of the color pixel. This produces a hybrid output for ideal display. 

In a study by Kumamoto Chuo Hospital, Japan, this blended pixel-by-pixel method was confirmed by 77% of participants to be of equal quality to Gamma 2.2 when viewing color images. Furthermore 94% of participants stated that grayscale images were displayed equivalent to GSDF, the same as they would be displayed on a monochrome monitor.

Using this function, both monochrome and color images can be displayed side by side on the same screen without losing any quality compared to standard methods. However by using Hybrid Gamma PXL the user no longer needs to change the modes of the monitor in order to view images correctly.  With this, diagnostic accuracy can increase, and diagnosis should become quicker and easier.

This function is available with several of EIZO’s RadiForce G&R Series color monitors, including the RX560 which was used in Kumamoto Chuo Hospital’s tests.

For further information on this test, please click here

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