Colour texture

The colour and texture are two elements of art that enhance the image feature. The colour is an important feature that beautifully transforms the image. The texture is the characteristic of an image that portrays the surface quality of the image. This study material covers the features of colour and texture in images or radiation. The law of colour explains the mixing concept of spectral and non-spectral colours.

Colour 

Colour is the element of art, formed by the reflection of light on the object. When the incident light strikes or hits an object, it gets reflected and reaches our human eye. It has a specific range of wavelengths that is visible to our eyes. The electromagnetic spectrum comprises these wavelengths.

The brain and eye both respond to light and sensory data. The mind visualises the data, compares it with memory and interprets the colour. 

Colourimetry

The colour can be measured by colourimetry. The amount of light present at each wavelength can be calculated by a spectrophotometer. 

Properties of colour

There are three important properties of colours such as

• Saturation value
• Intensity or chroma
• Hue

Saturation

Saturation refers to relative purity. For example, when we mix a strong, concentrated, red colour with, we get pale red. This pale red will have the same hue and different saturation points. These pale colours are called unsaturated colours.

Intensity or chroma of the colour

The hue and saturation are combined to form a variable bright colour quality, which is called intensity or chroma. It varies from colour to colour, depending on the total amount of energy present in the colour.

Hue

Hue is associated with yellow, red, and orange. 

Law of colour

We can distinguish a colour based on its ability to mix with other colours. These colours are chromatic and achromatic. The chromatic colours belong to the electromagnetic spectrum. The achromatic or non-chromatic colours come under black, grey and white sequences, for example, pink, brown and magenta. 

The human eye can distinguish 10.5 million colours, derived by additive and subtractive colour properties.

Additive property

The spectral components or light beams are added to obtain the additive mixture. The Newton’s colour circle combines syan, red, yellow, blue violet (spectral), with the magenta colour ( non-spectral) . This circle can be used to study the qualitative behaviour of beams. 

Subtractive property

The spectral components or parts are removed or absorbed to get the subtractive mixture. In subtractive mixing, the coloured filters or dyes are inserted into the individual beam of light. It results in selective reflection or transmission of light. 

Texture

As previously discussed, texture defines the quality of art or image surface. The particles of a surface body get disposed of or unite to form a specific surface. The pattern of local variations gets repeated in image intensity. It is used to classify or partition the image regions. 

The human can distinguish or section the image feature. This analysis enhances image segmentation in computer vision applications. It helps in encoding the storage and transmission images. 

There are two types of surface quality such as

• Visual surface quality
• Tactile surface quality

Texture Features

The texture can be analysed using the following methods

• Local binary pattern
• Grey level co-occurrence matrix
• Coordinated clusters representation
• Ranklets
• Gabor filters

Applications of texture

Using the texture property, we can examine the perception of low and high luminance in white and dark objects. 

Feature combination of colour and texture

We can view the appearance of a material or image from a different perspective using colour and texture. In order to explain this combination, many hybrid models were proposed such as joint distribution, concatenation and fusion of classifiers. 

Conclusion

In this article, we discussed the concept of colour and texture. Both are the elements of art or radiation, which enhance the human eye’s perspective. The three attributes or properties of colour were discussed with the law of colour. The texture is a definition of surface quality. The types, property features and applications of texture analysis were covered. Eventually, the hybrid model of colour and texture were explained.