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September 5, 2022

Why to use grayscale conversion during image processing?

September 5, 2022

What is grayscale?

It is an image conversion technique in digital photography. It eliminates every form of colour information and only leaves different shades of gray; the brightest being white and the darkest of it being black. Its intermediate shades usually have an equal level of brightness for the primary colours (red, blue and green). Alternatively it uses equal amounts of cyan, yellow and magenta which are the primary pigments. Each pixel is a representation of the luminous intensity of the image.

What are the categories of grayscale?


By  random action, they  alter the colour channels of an imputed image-making the system to consider alternate colour shades for the object. It causes edges and shapes of objects to be noticed rather than their distinct colours.


It involves adjusting the vibrancy of the pixel and that also of the image colour.


It varies from a scale of 0-100. The lower the level the darker the shade and the higher the level the higher the shade . The shades are between black and white.

What is image processing?

It is the art of converting an image into a digital format in a way that is either manipulated or enhanced for data extraction.

What are the categories of image processing? 

Image segmentation

It is the digital technique of dividing or partitioning an image into various parts or regions taking into account the image's pixels. An example of this is object detection.

Computer Vision

It is a field in artificial intelligence which trains computers in a way to make them understand and draw meaningful data from digital images and videos. One example of how computer vision works is in road lane detection.

Image analysis

Image analysis is the processing of an image into components to draw useful information from them. Included in this are objects counting and finding shapes. 

Face detection

Face detection is a digital application which identifies facial features in images. An example is seen in the Google photos app where photos of the same people are automated into individual albums.

How is an image converted into grayscale?

The average pixel values(ranging from 0-255) of the primary colours which are red green and blue (popularly referred to as RGB) are combined.  The luminous intensity of each colour band(which is 24 bits) is combined into a reasonable approximated grayscale  value(8 bits)

Why is grayscale needed for image processing?

It helps in simplifying algorithms and as well eliminates the complexities related to computational requirements.

It makes room for easier learning for those who are new to image processing. This is because grayscale compressors an image to its barest minimum pixel.

It enhances easy visualisation. It differentiates between the shadow details and the highlights of an image because it is mainly in 2 spatial dimensions (2D) rather than 3D. 

Colour complexity is also reduced. A typical 3D image requires camera calibration on brightness among others. The grayscale conversion option is very useful for captured images which do not need to match coloured detail.

Best use case of grayscale in image processing :Image segmentation and object detection in the medical field.

Grayscale conversion has been used in medical practice for computer aided diagnosis. It is very crucial as the images from ultrasound X-Ray and computer tomography (CT) scans rely heavily on them to give the right advice and treatment.

Image segmentation is vital here as the various organs and tissues of the human body have different values in grayscale. Images captured by medical staff are segmented to differentiate the various anatomical structures. That way the unique features and defects of each organ or tissue is easily identified. 

The 3D technology creates bounding boxes which makes objects easily detected. The 2D object detection also highlights areas of specific medical interest. 

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