Style Transfer GANs (Generative Adversarial Networks)

Style Transfer Generative Adversarial Networks take two images and apply the style from one image to the other image. Here are some sample results from here.

Style Transfer GAN examples

For a more technical explanation of how these work, you can refer to the following papers;

Image Style Transfer Using Convolutional Neural Networks
Artistic style transfer for videos
Preserving Color in Neural Artistic Style Transfer

Ever since first seeing this technique I wanted to add it as an image processing option within Visions of Chaos.

If you only want to play around with style transfer or only have a few photos you want to experiment with, then I recommend you use an online service like DeepArt because this can be a tedious process to setup and use on your own PC.

Installing Style Transfer Prerequisites

Follow these steps to get Python, Python Libraries, CUDA and CuDNN installed.

Style Transfer in Visions of Chaos

Generate any image, then select Image->Image Processing->Style Transfer.

Visions of Chaos Style Transfer GAN

The first time you select Style Transfer it will download the 500 MB neural network model that is used for all the style transfer magic.

Start with smaller image sizes to get an idea of how long the process will take on your system before going for larger sized images.

You can also select any external image file to apply the style transfer to. So dig out those cat photos and have fun. Note that if you get tired of the limited style images that come with Visions of Chaos, you can put any image you like under the Style Transfer folder (by default this will be C:\Users\\AppData\Roaming\Visions of Chaos\Examples\TensorFlow\Style Transfer\) and use those. Grab an image of your favorite artist’s works and experiment.

For these next examples I used the following photo of Miss Marple.

Miss Marple

And applied some various transfer style images.

MC Escher Plane Filling II

Miss Marple Style Transfer GAN

A Mandelbrot fractal

Miss Marple Style Transfer GAN

Another Mandelbrot fractal

Miss Marple Style Transfer GAN

HR Giger Biomechanical Landscape

Miss Marple Style Transfer GAN

Kandinsky Composition VII

Miss Marple Style Transfer GAN

Mondrian

Miss Marple Style Transfer GAN

Monet

Miss Marple Style Transfer GAN

Picasso Les Femmes d’Alger

Miss Marple Style Transfer GAN

Picasso Seated Nude

Miss Marple Style Transfer GAN

Hokusai The Great Wave off Kanagawa

Miss Marple Style Transfer GAN

Munch The Scream

Miss Marple Style Transfer GAN

Turner The Wreck of a Transport Ship

Miss Marple Style Transfer GAN

van Gogh Starry Night

Miss Marple Style Transfer GAN

How It Works

Behind the scenes the Style Transfer uses Cameron Smith’s excellent Python script from here. After trying various Style Transfer related scripts that one gives the sharpest and most interesting results. See that link if you want to run these sort of style transfers yourself from the command line outside Visions of Chaos.

Troubleshooting

If you get a failed style transfer and an error message, here are a few things to try;
1. Smaller image size. Depending on the RAM in your PC and GPU you may have maxed out.
2. Wait 30 seconds and try again. This seems to help sometimes.
3. Reboot. If all else fails. Seems to always fix a stubborn error for me. The Cuda and/or cuDNN seem to be the main culprit. They get hung or locked or something and only a reboot will get them working again.

Jason.

Automatic Color Palette Creation

Fractint MAP format palette files

Going back 30 years, Fractint was a fractal generation program for DOS based systems. For its time it was the fractal program of choice for enthusiasts.

Fractint used a simple text format for its color palettes. These *.MAP files were text files with each color’s RGB values separated by spaces each on a new line. So, for example if you wanted the first color in your palette to be blue the first line would be “0 0 255”.

When I first started creating Visions of Chaos I adopted the format. The most common map files had 256 colors (you could have palettes with other color counts but I only use 256 color palettes).

The rest of this post covers the palette creation methods that have been included with Visions of Chaos. Although I use these methods specifically to create 256 color MAP files the principles could be applied to any number of colors for different sized palettes.

If you are just looking for a Fractint color palette collection, scroll down to the end of this post and grab the archive provided.

Smoothly blending colors

Visions of Chaos Color Palette Editor

This is probably the first and most obvious method to use. Take a small number of base colors (I allow up to 16) and blend them into a palette.

How you get the colors to blend can be;

1. User selects them from the standard color picker dialog.
2. User can use eye dropper functionality to pick them out of a photo.
3. Set them at random.
4. Use the color wheel. Allows selection of complmentary colors, tetrads, and other color theory based colors.

Visions of Chaos Color Palette Editor

5. Extract colors from an image. See this previous blog post explaining how that works.

Visions of Chaos Color Palette Editor

Once you have the colors there are numerous ways you can blend them;

1. Smooth blend. Smoothly interpolate the colors.

Visions of Chaos Color Palette Editor

2. Fade out blend. Fade each of the colors to black.

Visions of Chaos Color Palette Editor

3. Fade in blend. Fade each of the colors from black.

Visions of Chaos Color Palette Editor

4. Neon blend. Fade from black to the colors then back to black.

Visions of Chaos Color Palette Editor

5. Stripe blend. Alternate each color for the duration of the palette.

Visions of Chaos Color Palette Editor

Using curves to create palettes

The idea here is to use various mathematical functions to generate curves for the RGB components of the palette. The following is a list of the various methods I use so far.

Sine. Each RGB color component is its own sine wave. Randomize the wave amplitude, frequency and period.

Visions of Chaos Color Palette Editor

Multiple Sine. Add multiple sine waves together for each RGB component and then scale down to between 0 and 255.

Visions of Chaos Color Palette Editor

IQ. Idea from Inigo Quilez.

Visions of Chaos Color Palette Editor

Perlin. Use repeating noise loops as in this coding train video. Map the resulting noise values to each RGB channel. Using a looping noise function is best because it means the palette wraps around smoothly and using it for fractal zooms does not show a sharp break when the palette ends and restarts. I have only implemented this method over the last few days (at the time of writing this post), but so far it gives some really unique color palettes.

Visions of Chaos Color Palette Editor

Here are some examples palettes created using Perlin noise. Click to see the full sized image.

Visions of Chaos Color Palette Editor

Simplex. Same as Perlin, but uses Simplex noise.

Visions of Chaos Color Palette Editor

Simplex + Perlin. Create each RGB value by adding Simplex noise to Perlin noise.

Visions of Chaos Color Palette Editor

Here are some examples of Simplex and Simplex + Perlin palettes. Click for full size.

Visions of Chaos Color Palette Editor

Multiple Perlin – Add/subtract multiple Perlin Noise curves into RGB amounts.

Visions of Chaos Color Palette Editor

Random Walk. Random curve for each RGB component between index 0 and 127. Reverse for the rest of the palette. Each step the RGB is changed by +random(5)-2 to randomly go up and/or down.

Visions of Chaos Color Palette Editor

Terrain Fault. Take 2 random points between 0 and 255. Between the points randomly raise or lower by a small amount. Repeat this a number of times.

Visions of Chaos Color Palette Editor

HSL to RGB. Random HSL curves converted to RGB.

Visions of Chaos Color Palette Editor

RGB. Random curves for each RGB component. Use various easing functions to tween curve control points.

Visions of Chaos Color Palette Editor

YUV to RGB. Random YUV curves converted to RGB.

Visions of Chaos Color Palette Editor

Combine palettes. Take 2 previously created palettes and combine their RGB components by addition, subtraction or multiplication.

Visions of Chaos Color Palette Editor

Multiple RGB. Combine multiple RGB curves.

Visions of Chaos Color Palette Editor

Multiple YUV to RGB. Combine multiple YUV to RGB curves.

Visions of Chaos Color Palette Editor

Modify an existing palette

Once you have palette files, you can also use various techniques to modify them;

1. Increase or decrease the individual RGB channel amounts
2. Brightness
3. Contrast
4. Increase or decrease the individual YUV channel amounts
5. Wrap. Take the existing palette, halve it, then add the flipped half to itself. This is useful when you want a non repeating palette to wrap around.

Visions of Chaos Color Palette Editor

Visions of Chaos Color Palette Editor

6. Double. If you have a palette that is too smooth/sparse for the current fractal image, doubling can add more lines/gradients to the palette.

Visions of Chaos Color Palette Editor

Visions of Chaos Color Palette Editor

7. Blur. Just like a blur function in image processing. Averages out the palette values with neighbor colors.
8. Sharpen. Just like a sharpen function in image processing.
9. Shift RGB. R->G,G->B,B->R.

Visions of Chaos Color Palette Editor

Visions of Chaos Color Palette Editor

Visions of Chaos Color Palette Editor

10. Invert. R=255-R, G=255-G, B=255-B.
11. Reverse. Flip the order of the palette colors.
12. Histogram equalize palette. Like the auto-levels in Photoshop. My method tends to make the results slightly too bright. Needs fixing when I get a chance.

Visions of Chaos Color Palette Editor

Visions of Chaos Color Palette Editor

13. Matrix multiplication. Take a 3×3 matrix and multiply the 1×3 RGB components by the matrix to get new RGB amounts.

Visions of Chaos Color Palette Editor

Any other ideas?

If you know of any other ways to generate palettes, or have an idea for ways to create new unique color palettes, let me know.

Availability

The color palette editor shown in this post is included with Visions of Chaos.

Just give me the palettes!

If you are using another program that uses Fractint palette files you can download the 3371 color palettes I include with Visions of Chaos here. Some created by me, others found on various Internet sites over the years, some converted from gradient packs. No copyright on them so do with them as you wish.

If you do have any other sets of MAP palettes you would like to share, send me an email. You can never have enough colors when creating fractal images.

Jason.

Vorticity Confinement for Eulerian Fluid Simulations

Eulerian MAC Fluid Simulation with Vorticity Confinement

Eulerian fluid simulations simulate the flow of fluids by tracking fluid velocity and density over a set of individual (discreet) evenly spaced grid locations. One downside to this approach is that the finer details in the fluid can be smoothed out, so you lose those little swirls and vortices.

Eulerian MAC Fluid Simulation with Vorticity Confinement

A simple fix for this is to add Vorticity Confinement. If you read the Wikipedia page on Vorticity Confinement you may be no wiser on what it is or how to add it into your fluid simulations.

Eulerian MAC Fluid Simulation with Vorticity Confinement

My explanation of vorticity confinement is that it looks for curls (vortices) in the fluid and adds in velocity to help boost the swirling motion of the fluid. Adding vorticity confinement can also give more turbulent looking fluid simulations which tend to be more aesthetically pleasing in simulations (unless you are a member of team laminar flow).

Eulerian MAC Fluid Simulation with Vorticity Confinement

The code for implementing vorticity confinement is relatively simple. For 2D I used the snippet provided by Iam0x539 in this video.


function Curl(x,y:integer):double;
begin
     Curl:=xvelocity[x,y+1]-xvelocity[x,y-1] + yvelocity[x-1,y]-yvelocity[x+1, y];
end;

procedure VorticityConfinement(vorticity:double);
var dx,dy,len:double;
    x,y:integer;
begin
     for y:=2 to _h-3 do
     begin
          for x:=2 to _w-3 do
          begin
               dx:=abs(curl(x + 0, y - 1)) - abs(curl(x + 0, y + 1));
               dy:=abs(curl(x + 1, y + 0)) - abs(curl(x - 1, y + 0));
               len:=sqrt(sqr(dx)+sqr(dy))+1e-5;
               dx:=vorticity/len*dx;
               dy:=vorticity/len*dy;
               xvelocity[x,y]:=xvelocity[x,y]+timestep*curl(x,y)*dx);
               yvelocity[x,y]:=yvelocity[x,y]+timestep*curl(x,y)*dy);
          end;
     end;
end;

Eulerian MAC Fluid Simulation with Vorticity Confinement

The VorticityConfinement procedure is called once per simulation step. It looks for local curl at each fluid grid point and then increases the local x and y velocities using the curl. This is what helps preserve the little vortices and helps reduce the smoothing out of the fluid.

Eulerian MAC Fluid Simulation with Vorticity Confinement

To demonstrate how vorticity confinement changes a fluid simulation, the images within this post and the following movie add vorticity confinement to my previous Eulerian MAC Fluid Simulations code.

Eulerian MAC Fluid Simulations with Vorticity Confinement is now included in the latest version of Visions of Chaos.

Jason.

Eulerian Marker-and-Cell Fluids

Eulerian MAC Fluid Simulation

Benedikt Bitterli has a set of YouTube videos that have been an inspiration for years.

Eulerian MAC Fluid Simulation

He generously shares the source code to a series of programs on his Incremental Fluids GitHub that cover implementing a 2D fluid simulation. His code is based on Robert Bridson’s book, “Fluid Simulation for Computer Graphics”. I have seen that book mentioned all over the place and almost bought a copy, but reviews say it is focused more on the math (not so helpful to me) and not on the code (which I can follow much easier than math formulas).

Eulerian MAC Fluid Simulation

So far, I have converted Benedikt’s first and second programs for inclusion in Visions of Chaos. Calculations at 4K resolution were originally taking up to 10 minutes per frame, but with some multi-threading and code optimizations I got it down to around 10 seconds per 4K resolution frame on a relatively modern i7 CPU.

Eulerian MAC Fluid Simulation

The results so far are really nice. The resulting flows show very high detailed vortices and fluid behavior.

Eulerian MAC Fluid Simulation

Here is a sample 4K resolution movie showing these fluids in motion.

Eulerian Marker-and-Cell Fluid Simulations are now available in the latest version of Visions of Chaos.

Jason.