docs(unit1): fix repetitive wording in 'Image' definition

chapters/en/unit1/image_and_imaging/image.mdx

@@ -6,7 +6,7 @@ It might be weird that we will explain to you what an image is in a Computer Vis
 
 An image is a visual representation of an object, a scene, a person, or even a concept. They can be photographs, paintings, drawings, schemes, scans and more! One of the more surprising things is that an image is also a function. More precisely, an image is an n-dimensional function. We will first consider it to be two-dimensional \\(n=2\\). We will call it \\(F(X,Y)\\), where \\(X\\) and \\(Y\\) are spatial coordinates. Do not get distracted by the fancy name. Spatial coordinates are just the system that we use to describe the positions of objects in a physical space with the most common one being the 2D Cartesian system. The amplitude of F at a pair of coordinates \\(x_i, y_i\\) is the intensity or gray level of the image at that point. The intensity is what gives you the perception of light and dark. Typically, when we have the coordinate pair \\(x_1\\) and \\(y_1\\), we refer to them as pixels (picture elements).
 
-Images are discrete, and the processes involved in assembling them are continuous. The image generation processes will be discussed in the next chapter. Right now, what matters is that the value of \\(F\\) at specific coordinates holds a physical meaning. The function \\(F(X,Y)\\) is characterized by two components: the amount of illumination from the source and the amount of illumination reflected by the object in the scene. Intensity images are also constrained in their intensity since the function is typically non-negative, and their values are finite. 
+Images are discrete, and the processes involved in assembling them are continuous. The image generation processes will be discussed in the next chapter. Right now, what matters is that the value of \\(F\\) at specific coordinates holds a physical meaning. The function \\(F(X,Y)\\) is characterized by two components: the amount of illumination from the source and the amount of illumination reflected by the object in the scene. Images are also constrained in their intensity since the function is typically non-negative, and their values are finite. 
 
 That is not the only way one can create an image.  Sometimes, they are created by computers with or without the help of AI.  We have a dedicated chapter for images that do have a little helping hand from AI. Most of the terminology we will introduce here will still be applicable.