update readme

README.md

@@ -1,13 +1,38 @@
-## Compute shader with Vulkan
+# Compute shader with Vulkan
 
-#### Initialization of a Vulkan program to execute a compute shader.
+### Initialization of a Vulkan program to execute a compute shader.
 
-### Contents
+## Contents
 - [Introduction](#Introduction)
 - [Initialization](#Initialization)
 
 <a name='Introduction'></a>
 
 ## Introduction
 
-Something that Vulkan have different than another graphic API it's that it add one more step in the process to start to work with GPU. It works with an instance.
+Compute shaders are a special type of shader that doesn’t use the fixed graphics pipeline, and just allows to run arbitrary computations on the GPU.
+
+Generation of an image(1000x1000) of a simple fractal and compare the processing time(miliseconds) needed by the CPU and the GPU:
+
+
+#### &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; CPU time: 285 ms.   &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;   GPU time: 4 ms.
+<p align="left">
+ <img height="230px" src="https://github.com/esettes/compute_shader_vulkan/blob/main/img/fractal_cpu.png" />
+ <img height="230px" src="https://github.com/esettes/compute_shader_vulkan/blob/main/img/fractal_gpu.png" />
+</p>
+<a name='Initialization'></a>
+
+## Initialization
+
+### 1. Create an instance
+
+Something that Vulkan have different than another graphics API it's that it add one more step in the process to start to work with GPU. It works with an instance.
+
+Validator layers are included here --
+
+### 2. Obtain physical device
+
+Enumerate all physical devices from the instance. `vkGetPhysicalDeviceProperties` allows to see significant information about each device.
+
+3. 
+