There are different types of gradients, including the horizontal gradient, here are a few examples with gradients in the horizontal direction of the gradient!The gradient as a horizontal!
In a graphic software for digital image processing, the term color gradient is also used for a gradual color mixing and is often referred to as a gradient! But what does it tell you about the gradient, whether it is horizontal or vertical, here are a few examples with horizontal gradient! Content / examples: 1.) ... A red into the blue gradient.

(Image1) Red into the blue gradient horizontally! 
The gradient of the image is one of the fundamental building blocks of image processing!
......
2.) Horizontal purple / yellow gradient.
(Image2) Gradient horizontal purple to yellow 
An image gradient is a change in direction in intensity, or color, in an image.
3.) Green to black as a horizontal gradient!
(Image3) Gradient from green to black tone horizontally! 
Mathematically, the gradient of a function with two variables at each pixel is a vector with the components given by the derivatives in the horizontal direction.
FAQ 117: Updated on: 28 June 2020 19:14