Update README

Author: pjg11

README.md

@@ -6,23 +6,31 @@ A attempt at the [Ray Tracing in One Weekend](https://raytracing.github.io/books
 
 ```
 $ make
-$ ./main > section14.ppm
+$ ./main > cover.ppm
 ```
 
-The resulting image is the cover image of the book: 1200x675px, 500 samples/pixel. Running `./main -small` generates a smaller image for testing purposes - 400x225px, 100 samples/pixel.
+The resulting image is the cover image of the book: 1200x675px, 500 samples/pixel.
 
-The original, single-threaded implementation ran in 18m 41s with optimization flags enabled. Further optimizations reduced the time to 3m 31s, a 5.3x speedup. A writeup is in the works, so here's a summary:
+![Spheres of different size, color and material](cover.jpg)
 
-* Multi-threading (4 threads) - 62% faster
-* Implementation changes - 18% faster
-  * Changing from function pointers to enum + union for `scatter()`
-  * Change `raycolor()` from recursive to iterative
-  * Use custom random function instead of stdlib `rand()`
-* SIMD - 37% faster
-  * Add [ARM Neon](https://community.arm.com/arm-community-blogs/b/operating-systems-blog/posts/arm-neon-programming-quick-reference) instructions in `vec3` functions
-  * Vectorize `spherelisthit()` further to calculate 4 spheres at once
+The original, single-threaded implementation ran in 18m 41s with optimization flags enabled. Further optimizations reduced the time to 3m 31s, a 5.3x speedup. Here's a summary of optimizations with a smaller test image (`./main -small`) - 400x225px, 100 samples/pixel.
+
+| Optimization                                              | real   | user  | sys  | cpu% |
+| --------------------------------------------------------- | ------ | ----- | ---- | ---- |
+| Optimization flags (`-O2`, `-flto`)                       | 24.568 | 24.52 | 0.01 | 99   |
+| Multi-threaded pixel rendering (4 threads)                | 13.817 | 33.93 | 8.31 | 305  |
+| Multi-threaded scanline rendering                         | 9.459  | 36.43 | 0.02 | 385  |
+| Multi-threaded scanlines rendering                        | 9.261  | 36.68 | 0.01 | 396  |
+| Changing function pointer to enums + union                | 7.855  | 31.10 | 0.01 | 396  |
+| Use custom inline random instead of stdlib `rand()`       | 7.690  | 30.40 | 0.01 | 395  |
+| Change `raycolor()` to be iterative instead of recursive  | 7.519  | 29.72 | 0.01 | 395  |
+| Use ARM Neon SIMD instructions in vector functions        | 7.066  | 27.91 | 0.01 | 395  |
+| Use SIMD instructions to calculate 4 spheres at once      | 6.085  | 24.01 | 0.01 | 394  |
+| Improved data loading for "4 spheres at once"             | 5.847  | 23.09 | 0.01 | 395  |
+| Vectorized discrimiant check in `spherelisthit()`         | 4.902  | 19.32 | 0.01 | 394  |
+| Small improvements in `spherelisthit()`                   | 4.743  | 18.70 | 0.01 | 394  |
 
 ## Resources
-- [jacobvosmaer/raytracingweekend](https://github.com/jacobvosmaer/raytracingweekend/) + accompaniying [blog post](http://blog.jacobvosmaer.nl/0022-ray-tracing-weekend/)
+- [jacobvosmaer/raytracingweekend](https://github.com/jacobvosmaer/raytracingweekend/) + accompanying [blog post](http://blog.jacobvosmaer.nl/0022-ray-tracing-weekend/)
 - [jfeintzeig/ray_tracer](https://github.com/JFeintzeig/ray_tracer) + accompanying [blog post](https://www.jakef.science/posts/simd-parallelism/)
 - [ARM Neon Instruction Set](https://developer.arm.com/architectures/instruction-sets/intrinsics/#f:@navigationhierarchiessimdisa=[Neon])