DESC:FIELD OF THE INVENTION: The present invention relates to a CMOS image sensor that uses non-linear statistics and impulsive metrics for signal processing for RTS noise reduction. More specifically, the RTS noise reduction is achieved by sensing of impulsive metrics to obtain median value or higher order statistics of the input sequence, and specifically targeting RTS noise reduction to enhance and improve image quality. BACKGROUND OF THE INVENTION: Digital photography has advanced in leaps and bounds, incorporating features of advanced cameras in compact photographic devices due to rapid developments in image processing techniques. Despite the technological advancements, photography in low light conditions still poses a challenge to technologists working in this field. Even the available advanced cameras have failed to provide better efficiency and high resolution of picture in low-light conditions. Availability of light is a fundamental requirement for any digital camera, to process a captured image and render a high-resolution image as an output. This is the very reason why photography in low-light conditions renders an image of inferior quality. Obtaining a high-resolution image in low-light conditions is very important when it comes to applications, inter alia, in medical equipment and warfare equipment. For instance, low-light imaging finds a necessary use in endoscopic capsule, fluorescence microscopy, astrophotography, night-vision optics and other surveillance applications. There are image sensors available which have tried to attend the problems of low light photography. However, the images rendered are of an inferior resolution and are normally laden with noise signals. Further, few of these signal noises have non-Gaussian characteristics. One of the prominent types of the non-Gaussian signal noise present in digital photography is Random Telegraph Signal (RTS) noise. Generally, the random telegraph signal (RTS) noise seen at the pixel output is caused by the presence of a single trap level interacting with the channel charge carriers. The characterized signal in RTS noise is one in which the distribution of noise is random, haphazard and discrete fluctuations between two or more metastable states, and distributed as multiple Gaussian sub-populations. Alternatively, this implies that non-Gaussian signal noises are distributed unequally and non-uniformly with respect to time over the entire length of the signal thereby making the quality of signal poor. Further, such signal noises are characterized as random fluctuations of a continuous-time discrete-amplitude signal, and has a severe impact on the performance of modern CMOS image sensor due to aggressively flashing pixels. RTS noise is among one of the types of non-Gaussian signal noise wherein the variation of noise with respect to time is distributed non-uniformly and is in a haphazard manner. These signal noises severely affect the quality of image by producing twinkling effect in the image thereby making the image flash. Further, the cause of RTS noise in conventional CMOS image sensor is that there is a significant charge transfer time to avoid non-idealities of the transfer gate in the 4T active pixel photodiode. Primarily, conventional CMOS image sensor is only able to detect signal noises which are of Gaussian type. The Gaussian signal noises have the characteristics in which signal noise is uniformly distributed Another major problem present with the RTS noise is that its distribution with respect to time is in the order of nano-second. Conventionally, in the CMOS image sensor, to avoid Transfer Gate (TG) non-idealities in a 4T-pixel, a significant amount of time is required for transferring signal charges from the Pinned Photodiode (PPD) to the floating diffusion (FD) node. This leads to limited effectiveness of the Correlated Double Sampling (CDS), especially for small time constant Random Telegraph Signal (RTS) processes. Further, the RTS noise has a time-constants which are of the nanosecond order are completely uncorrelated between the reset and signal phase sampling in CDS. Further, another problem associated with the RTS noise is that it does not reduces drastically and is most difficult noise to reduce by any image sensor/s. This is one of the most difficult signal noises to capture and reduce drastically because it is of non-Gaussian type. Hence, conventional CMOS image sensor performance is always limited by the presence of RTS noise. Conventionally, the correlated multiple sampling method is used wherein a CMOS image sensor comprising a circuit capable of calculating the average of M successive samples of an output signal of a pixel of the sensor is used. Correlated multiple sampling circuit is unable to fully eliminate the RTS noise. The RTS noise is primarily generated in the in-pixel source follower transistor in a CMOS image sensor. The RTS noise has a Lorentzian spectrum i.e. it is one of the form of 1/f power spectrum. The noise signal is caused by the presence of a single trap level interacting with the channel charge carriers. Further, various linear statistics are also used to decrease the RTS noise in CIS technology, but they do not drastically decrease the RTS noise in the CMOS image sensors and hence does not produce good quality of image especially in low light environments. The available CMOS image sensors which reduce RTS noise and non-Gaussian noise are as follows: US9497400B2 discloses a CMOS image sensor for non-Gaussian noise reduction comprising one pixel and one circuit arranged to receive, on a first node of the circuit, an analog signal representative of the luminosity level received by the pixel, the circuit being capable of successively acquiring 2n samples of said signal, n being an integer greater than or equal to 2, and of delivering, on a second node of the circuit, an analog signal having a value equal to the average of the values of said samples, without generating an intermediate signal having a value greater than the value of the largest acquired sample, the circuit comprising: first and second capacitors, the second capacitor having a first electrode connected to the first node via a first switch, and a second electrode connected to a node of application of a reference potential, and the first capacitor having a first electrode connected to the second node and connected to the first electrode of the second capacitor via a second switch, and a second electrode connected to a node of application of the reference potential; n-1 branches, each comprising two switches in series between the first electrode of the second capacitor and the first electrode of the first capacitor, and a capacitor connecting the junction point of the two switches of the branch and a node of application of the reference potential; and a control unit capable of controlling the switches to successively acquire 2n samples of the voltage at the first node in the n+1 capacitors, and of delivering, across the second capacitor, a voltage equal to the average of the acquired samples. US10594967 discloses a sample-and-hold circuit which includes an amplifier transistor, a resistor connected between a source terminal of the amplifier and a predetermined voltage, a first switch connected in parallel with the resistor, and a second switch connected between a gate terminal of the amplifier transistor and the predetermined voltage. Further, US’967 discloses an image sensor that includes a pixel circuit configured to convert incident light into an analog signal; and a sample-and-hold circuit configured to receive the analog signal, wherein the sample-and-hold circuit includes an amplifier transistor, a resistor connected between a source terminal of the amplifier and a predetermined voltage, a first switch connected in parallel with the resistor, and a second switch connected between a gate terminal of the amplifier transistor and the predetermined voltage. In furtherance of this, US’967 also discloses a technique of periodic switching wherein when the first switch is closed and the second switch is open, the amplifier transistor is in an inversion mode; and when the first switch is open and the second switch is closed, the amplifier transistor is in an accumulation mode. So, the noise is reduced using the amplifier transistor. US9380234 discloses a reduced random telegraph signal (RTS)-noise CMOS image sensor wherein the image sensor includes a pixel and a correlated double sampling (CDS) circuit electrically connected to the pixel. The CDS circuit is characterized by a CDS period that includes a reference sample period and an image data sample period. The image sensor also includes a bit line, a bitline connection switch between the pixel and a readout circuit connected to the pixel, and a bitline switch controller. The bitline transmits a transfer gate signal as a bitline signal having a non-zero value during a first time period entirely between the reference sample period and the image data sample period. The bitline switch controller is electrically connected to and configured to control the bitline connection switch such that the bitline connection switch is closed during the entire CDS period except for a single continuous open period that includes the first time period. US8513102 discloses an active silicon MOS field effect device, defined on a substrate having a width dimension equal to or less than 350 nm and a length dimension equal to or less than 350 nm, has a conduction channel behind the gate electrode doped to an ionized dopant atom concentration in the range of between 1013 to 1015 atoms per cubic centimetre to reduce the random telegraph signal (RTS) and 1/f noise in the device. Further, US’102 discloses a nanoscale scale, or less than a 1000 nm scale, size effects can become important in determining the RTS or 1/f noise of CMOS transistors. The nanoscale is the size at which the expected fluctuations of the averaged properties due to location of individual particles cannot be reduced to below some desirable threshold of a few percent. For dimensions less than 1000 nm, or atomic dimensions of 1000 Å, the locations of individual atoms and electronic charges become important and result in an apparent amplification of random telegraph signal, RTS, noise in nanoscale transistors currently being used in MOS and CMOS memory, logic, and imaging devices. Further, US’102 discloses usage of a planar NMOS transistor that may be in CMOS configuration is fabricated on a substrate with very low doping of 1015 atoms per cubic centimetre resulting in a very low concentration of ionized acceptor impurity atoms. A range of values from 1013 to 1015 atoms per cubic centimetre is preferred. The transistor has conventional source, drain, and gate structures. The effective substrate doping can be made even lower by counter doping with donor type impurities. The low substrate, or low effective substrate, doping results in few potential peaks in the channel and fewer percolation channels and consequently lower RTS noise. Thus, conventional method of reducing RTS noise require substantial changes in the structure of the photodiode. Due to this reason, process of reducing RTS noise components is quite expensive. Further, due to structural changes in CMOS image sensor, there is an increase in number of components which impacts overall size and operational requirements of the CMOS image sensor. Therefore, conventional method is yet not enough to substantially reduce RTS components because RTS noise components is still present in few of pixels of the photodiode and is sufficient enough to hamper quality of the image. The reason is that the source follower transistor causes an occurrence of trapped electrons in holes during operation of an overall voltage gain. Even presence of few RTS noise components in the signal causes a reduction in the image quality. So, drastic reduction of RTS noise is very important to improve the image quality. Further, the RTS noise components has a time-constant of the order of nano-second and conventional method still requires significant charge transfer time which thereby causes few pixels to have RTS noise components. Thereby, there is requirement of a CMOS image sensor wherein the time constant is of order of nano-second to eliminate random telegraph signal (RTS) noise substantially to improve quality of the image. Another requirement is to provide a CMOS image sensor which do not substantially changes the architecture of the CMOS image sensor and specifically the composition of active area and the pixel overall is not changed. So, it is an object of the present invention to overcome the problems present in the prior art and provide an improved CMOS image sensor which provide better quality of image by drastically reducing RTS noise. Thus, the present invention provides a CMOS image sensor which uses non-linear statistics and impulsive metrics for signal processing for carrying out drastic RTS noise reduction. SUMMARY OF THE INVENTION: There is a need for a more effective, competent, efficient, compact, economical, and a high dynamic range CMOS image sensor, which uses a novel analog signal processing method based on correlated impulsive metrics like maxima, minima, median value of the RTS noise and higher order statistics for multiple sampling to decrease RTS noise. The present invention relates to a CMOS image sensor that uses non-linear statistics and impulsive metrics for signal processing for RTS noise reduction. The RTS noise reduction is achieved by sensing of impulsive metrics to obtain median value or higher order statistics of the input sequence, specifically targeting RTS noise to enhance and improve the image quality. The RTS noise reduction CMOS image sensor comprises of a plurality of 4T active pixel photodiode, wherein the 4T active pixel photodiode includes: a plurality of a pinned photodiode (PPD), wherein the pinned photodiode is configured to generate and accumulate photo electrons when light of pre-determined wavelength is incident on them; a plurality of a transfer gate (TG), wherein the transfer gate is configured to transfer the photo generated electrons from the PPD to the floating diffusion node (305) and store them for pre-determined duration; a plurality of a reset transistor (MRST), wherein the MRST reset the floating diffusion node to eliminate residual signal from floating diffusion node of the PPD; a plurality of a reset signal switch, wherein the reset signal is configured to operate the MRST in ON/OFF mode; a plurality of a source follower (SF) transistor, wherein the source follower converts the charges stored on the floating diffusion node to a voltage with a pre-determined voltage gain; a plurality of a row selection (RS) transistor, wherein the row selection is configured to read each row present in PPD; and a plurality of column current source in between the row selection transistor and a column level readout circuit, wherein the column current source is grounded. Further, the column level readout circuit comprises of: a plurality of low-level noise column level amplifier (CLA), wherein the CLA is configured to provide sufficient gain to signal received from source follower for suppressing noise; a plurality of thermal noise filter, wherein the thermal noise filter is configured to filter out thermal noise components from RTS noise components; a plurality of maxima detector and minima detector, wherein the maxima detector and minima detector are configured to provide maxima value and minima value to input signal provided by thermal noise filter; a plurality of sample and hold reset (SHR) switch, wherein the SHR switch is configured to hold obtained median value provided by the maxima and minima detectors respectively; a plurality of sample and hold signal (SHS) switch, wherein the SHS switch is configured to hold signal obtained through median value provided by the maxima and minima detectors respectively; a plurality of analog to digital convertor (ADC), wherein the output from the SHR and SHS switches are provided to positive node and negative node of ADC respectively; and a means to provide digital number generated by the ADC which is a representative of the voltage level at the input of the ADC. Further, the present CMOS image sensor is effective, competent, efficient, and has a high dynamic range for RTS noise reduction through sensing impulsive metrics by obtaining median value and/or higher order statistics of input sequence targeting RTS noise to enhance and improve image quality. The present invention relates to a novel method for RTS noise reduction which is achieved by application of higher order statics in the output of a CMOS image sensor. The method includes: Initial charging of a capacitor C1 and capacitor C2 to an initial voltage of Vss and Vdd respectively; Sampling of an input voltage at Vin that is obtained from the output of a thermal noise filter; Comparing the sampled input voltage Vin with the voltage stored across the capacitor C1 and the capacitor C2 using comparators; On comparing Vin with Vc1 it is determined that VinVc1 and VinVc1, the circuit follows the next step 605, wherein according to the condition as mentioned in the step (607), switch S1 is turn ON and the capacitor C1 is charged linearly for a pre-determined time duration until Vin=V_C1. This provides maxima values from the input sequence and is stored at Vo1. On comparing Vin and Vc2, if VinVc1, then a switch S1 is turned ON and the capacitor C1 is charged linearly for a pre-determined time duration until Vin=V_C1; - on comparing Vin and Vc2 if Vin