## 3 Experimental Data and Results
### Usefulness of Camera-Based Optical Communications in the Detection Process
#### 3.1.3 Projective Exposure of Regressive Transformations by Parameterizable Methods and Histograms
Then the points \(A\) and \(A^{\prime}\) are homogeneous, and their coordinates are (\(A_{X}\), \(A_{Y}\), \(A_{Z}\)) and (\(A^{\prime}_{Y}\), \(A^{\prime}_{Y}\), \(A^{\prime}_{Z^{\prime}}\)), respectively. The matrix dedicated to the transformation is denoted by \(\boldsymbol{T}=[t_{ij}]\), representing a three-row and three-column irreversible matrix with a point coordination relation:  
\[\left[ \begin{array}{c}A_{x}\\ A_{y}\\ A_{z}\end{array} \right]=\left[ \begin{array}{ccc}t_{11}&t_{12}&t_{13}\\ t_{21}&t_{22}&t_{23}\\ t_{31}&t_{32}&t_{33}\end{array} \right]\times\left[ \begin{array}{c}A_{x}{}^{ \prime}\\ A_{y}{}^{\prime}\\ A_{z}{}^{\prime}\end{array} \right] \tag{6}\]  
When the determination is made for all the elements contained in matrix \(\boldsymbol{T}\), the three points \(A\), \(B\) and \(C\) and their projections are transformed according to the matrix exposure \(A^{\prime}\), \(B^{\prime}\) and \(C^{\prime}\). The images were converted by applying the Otsu method and reducing the gradient in the image by applying grayscale. This favors the operation of the thresholds imposed by Otsu in the case of two-dimensional images, thus converting to grayscale by syntax gray_img = rgb1 gray (img) and plotting imshow (gray_img, cmap = \"gray\"), outlining that gradient map after exposing it as image transposed coordinates. The histogram generated by performing the exposed iterations offers the possibility of scattering colors in images, and the x-axis represents that scattering of colors. By the Otsu method, the pixels in the background are imperatively divided but also in the foreground with the successive imposition of a minimum color threshold to which a maximum color threshold is imposed. The imposed threshold must satisfy the variation within the inner class in relation to the threshold (see Figure 7). Figure 8 illustrates a diagram of an S-VLC communication system, which uses smartphones for reception and a street light for transmission. The traffic light system transmits the information through the LED light, based on the wiring diagram shown in Figure 9a. The camera of the receiving phone captures the signal emitted from Tx. When the Tx light beam emits data, an encoded image creates a black-and-white gradient map demodulating the information. The camera at the Rx reception point captures the information in the visual field of view (FOV). Figure 6: Exemplification of a projective transformation for distorting a rectangle—extraction capabilities. In the case of the block diagram for the Tx emission, this is described in Figure 9b. The input information goes through a binary conversion, then an image composed of several cells is used, and this cell contains an x number of pixels. The pixels in the same cell are assigned the same intensity. Subsequently, a stage of modulation of the communication signal is performed. At this stage, there are three ways to modulate the signal, and they are viable:  
1. Black and white cells/pixels: the outline of each cell, whether black or white, is a bit rate. When we have the modulation output in the form of an M \(\times\) N matrix, it is allocated at intensity levels 0-255. Figure 8: Illustration of an S-VLC communication system, which uses smartphones for reception and a street light for transmission. Figure 7: The code instance that imposes a threshold on internal class variables. Figure 9: (**a**) Architecture of VLC emitter—camera processing. (**b**) Flow processing and binary stream conversion for frame detection. * Gradient cells/pixels (gray): for this operation, each binary model that is contoured follows a consecutive order with a quantity of 8 bits, being in turn represented by a decimal value 0-255. The output is also according to the matrix expression M \(\times\) N.
* RGB cells/pixels: for this color format, most of the pixels are represented by the following three color components, at different intensities between 0 and 255. Therefore, for each cell, an input data stream is represented for those bits.