Whether microscopy images are captured with a camera or microscopic samples are viewed with a monitor, the colors perceived by the human eye often vary from those captured by the camera or those seen on the monitor. This leads to the question: should we consider the color variations between the images seen through a microscope and those captured by a camera?
The Importance of Color Reproduction
Color reproduction is crucial for samples involving color, such as histology slides stained with hematoxylin and eosin. The accurate analysis and resulting comparison between these images with previous samples is very important.
If the color reproduction is poor, the contrast between colors is not clear and, as a consequence, it is possible to miss some important information. Hence, the images viewed by the microscope must be adjusted to account for the light source.
In image processing, this chromatic adaptation is known as 'white balance' or 'color balance'. Image sensors such as photomultiplier tubes or camera sensors acquire data, which are then processed for color reproduction on camera displays or computer screens. Complementary metal oxide semiconductors (CMOS) and charge couple devices (CCD) are the two most widely used image sensors in microscope cameras.
It is possible to electronically adjust both CCD and CMOS cameras for white balance. However, since the monochromatic nature of the light sensing elements of these sensors, color balance can be attained by individual sensors covering each pixel in the sensor array, or by allowing the light to pass through red, green and blue (RGB) filters, which cover the whole sensor.
Color correction systems vary with each camera. Some systems are controlled by the software alone, whereas both software and hardware adjustments are required in other cases. In addition, users cannot alter some of these settings. This means that selecting a camera with a good color reproduction and color correction is very important.
The color reference matrix used by Lumenera’s 'Color Correction Matrices' (CCM) has been specifically designed for comparing each color component of the image in order to accurately reproduce colors under various lighting conditions. There will be a difference in color reproduction between microscopes, monitors, room set-ups and lighting conditions.
Additionally, there will be a difference in colors based on the samples, fluorophores or stains being used. It is recommended to use the same microscope system and ensure its proper alignment for Koehler Illumination.
This information has been sourced, reviewed and adapted from materials provided by Lumenera Corporation.
For more information on this source, please visit Lumenera Corporation.