# Creating a PNG image of a formula in generativepy

Categories: generativepy generativepy tutorial

In this article we will look at the simplest way to render a Latex formula as a PNG image using generativepy.

We will use the `rasterise_formula`

function of the `formula`

module. First, we will look at how a formula is defined.

## Latex

Latex provides a way to define mathematical formulas in plain text. For example, this Latex formula:

```
x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}
```

Defines the well-known formula for the solutions to a quadratic equation. When this definition is rendered, it looks something like this:

We won't go into details about how Latex works here, there are many examples online. This article just looks at how to render Latex as an image.

## generativepy

`generativepy`

is a Python library for creating generative art and mathematical illustrations in code. It has many features, but the one we will look at here is how to render Latex as a PNG image.

See the generativepy reference for details on how to install the library. You will also need NumPy installed, and the command line programs `latex`

and `dvipng`

.

## Converting Latex to PNG

Here is the Python code to convert a couple of equations to images:

```
from generativepy.color import Color
from generativepy.formulas import rasterise_formula
rasterise_formula("create-png-1", r"e^{i \pi}+1 = 0", Color("red"), dpi=800)
rasterise_formula("create-png-2", r"\frac{\cancel{a}b}{\cancel{a}c} = 0",
Color("green"), packages=["cancel"])
```

After importing a couple of required modules from `generativepy`

, we just need to call `rasterise_formula`

, passing in the three required arguments:

`name`

- the base name that will be used to create the PNG file. This file will always be created in the working folder.`formula`

- the Latex formula string. This is just the formula definition, it should not be enclosed in $ symbols, and you do not need`begin`

or`end`

text.- The colour of the text, as a
`Color`

object (defined in`generativepy.color`

). You can use any CSS named colours, and there are also lots of other ways to define a colour.

The first call above adds an optional `dpi`

parameter that controls the size of the image. The actual size of the image is determined by the formula itself, the `dpi`

parameter acts as a scale factor. The default is 600, but you can make the image bigger or smaller by using a larger or smaller dpi value. Here is the result:

Latex contains many optional packages that include extra features. The second call to `rasterise_formula`

shows how we can use packages when rendering Latex. We add a `packages`

argument consisting of a list of package names (in this case just on, the `cancel`

package). We can then use the Latex `\cancel`

operator in our function, which draws diagonal lines through the *a* characters to cancel them out. Here is the result:

## Summary

It is very easy to render Latex formulas in Python with the `generativepy`

library. In a future article, we will see how to add formulas to graphs and videos.

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