**Abstract**

Colorimetry is the determination of colors, as name indicates. This method can use for to find out the concentration of compound (solute) in a colored solution in terms of chemical analysis (solvent). We frequently need to quantify the quantity of a specific component in a combination or the concentration of a solution during scientific activity. The trick is to determine the color differences between various combinations and their absolute values. This is more instructive and scientifically valuable than relying on subjective judgments like the color of the solution. Colorimetry is the measurement of colors, as the name implies. It is the measurement of the concentration of a certain compound (solute) in a colored solution in terms of chemical analysis (solvent). We frequently need to quantify the quantity of a specific component in a combination or the concentration of a solution during scientific activity. The trick is to determine the color differences between various combinations and their absolute values. This is more instructive and scientifically valuable than relying on subjective judgments like the color of the solution. Colorimetry is used in a digital image-based (DIB) approach for determining active medicinal components. A computerized scanner with a controlled light intensity was connected to the detector. Different histograms were used to transform the photos. The colorimetric analysis of digital images provided for an easy-to-use and ecologically friendly method.

**Keywords:** colorimeter, digital image based (DIB) colorimetric analysis, quantification of color, UV-vis spectrophotometer, reflectance spectrophotometer, green active pharmaceuticals

#### **1. Introduction**

When a light of occurrence with intensity (Io) passes from a solution, a portion of the light is revealed (Ir), a portion is absorbed (Ia), and the rest is transmitted (It), Thus,

$$\mathbf{I}\mathbf{r} + \mathbf{I}\mathbf{a} + \mathbf{I}\mathbf{t} = \mathbf{I}\mathbf{o}$$

Because of the measurement of (Io), (Ir) is omitted in colorimeters, and it is sufficient to regulate the (Ia). The light will be replicated (Ir) is kept consistent for this purpose by using cells with identical characteristics. The values of (Io) and (It) are then calculated.

The two fundamental equations of photometry, on which the colorimeter is based, show the mathematical link between the amount of light absorbed and the concentration of the substance.

Beer's Law is a rule that states that if you drink.

The amount of light absorbed is directly proportional to the concentration of the solute in the solution, according to this rule.

$$\begin{aligned} \text{I0/It} &= \text{asc} \\ \text{Log10 (I0/It)} &= \text{asc} \end{aligned}$$

where,

as = Absorbency index.

C = Solution Concentration.

### **2. Lambert's rule**

According to Lambert's law, the amount of light absorbed is proportional to the length and thickness of the solution under investigation [1–5].

$$\begin{aligned} \textbf{I0/It} &= \textbf{a} \textbf{b} \\ \textbf{A} = \begin{array}{c} \textbf{I0}/\textbf{It} \\ \textbf{I0/It} \end{array} & \textbf{a} \textbf{b} \end{array} $$

where,

A = Test Absorbance. as = Standard absorbance. b = the solution's length/thickness.

#### **3. Instrumentation**

Components for Colorimeter,

The Colorimeter is a technique that measures the amount of absorbed light of a given wavelength in order to determine the concentration of a sample. Duboscq Colorimeter, created by Jules Doboscq in 1870, is one of the first and most popular designs. The components of a colorimeter are as follows:

1.A source of light to illuminate the solution, commonly a blue, green, or red LED.

*A Digital Image-Based Colorimetric Technique Use for Quantification of Green Active… DOI: http://dx.doi.org/10.5772/intechopen.101398*


#### **4. Colorimeter's process**


#### **5. The colorimetric principle**

Colorimetry is the measuring of electromagnetic radiation's wavelength and intensity in the visible spectrum. It's widely used for determining the quantities of light-absorbing compounds and identifying them. The equation log can be used to represent the two laws when they are combined. I0/I = kcd, where I0 is the incident light intensity, I is the transmitted light intensity, c is the absorbing substance concentration, d is the distance through the absorbing solution, and k is a constant that varies depending on the absorbing substance, the wavelength of light used, and the units used to specify c and d.

The intensity of radiation passed through layers of various thicknesses of two solutions of the same absorbing substance, one with a known concentration and the other unknown, is a straightforward application of this term. The equipment is known as a photoelectric colorimeter when it compares intensities using a photoelectric cell rather than the eye.

The comprehensive noticeable band (white light) is frequently employed in colorimetry, The flattering color of the one captivated is seen as transmitted light. The instrument is called a spectrophotometer if it uses homochromatic light or a

constrained band of radioactivity. It is used to demeanor dimensions in the ultraviolet and infrared regions as well as the visible spectrum. Colorimeters have mostly been superseded by spectrophotometers [8].

## **6. Color grading**

Colorimetry is a term for the measuring of color. This field employs a wide range of instruments. The most advanced, spectrophotometers, measure the quantity of energy in each spectral wavelength. The emittance curves for light sources (see figure) and the reflectance curve for the paint color emerald green (see figure) are typical spectrophotometer results.

Electromagnetic radiation is defined as the movement of photons (also known as light quanta) over space, according to contemporary quantum theory. Photons are energy packets that travel at the universal speed of light at all times. The symbol h stands for Planck's constant, and the value of corresponds to the frequency of an electromagnetic wave in classical theory. The numerical density of photons with the same energy h corresponds to the intensity of the radiation. The frequency of electromagnetic radiation influences these occurrences, as well as how it is made and viewed, how it occurs in nature, and how it is used in technology. The frequency spectrum of electromagnetic radioactivity varieties from extremely low values in the radio, television, and microwave ranges to noticeable light and elsewhere, too much sophisticated standards in ultraviolet light, X-rays, and gamma rays [9].

#### **7. Color measurement aspects**

A test bulb glows proceeding a bleached monitor, which is observed by an spectator, in a very ancient experiment. One or more of three lamps, each capable of producing light in three different colors, such as red, green, and blue, illuminate a neighboring section of the screen. The principal light is chosen at random, although it is tightly regulated. The observer can match the collective shade on the monitor to that of the test bulb by altering the intensities of these lights. The tristimulus value of a color is defined as the sum of the three primaries [10].

*A Digital Image-Based Colorimetric Technique Use for Quantification of Green Active… DOI: http://dx.doi.org/10.5772/intechopen.101398*
