# The **MuPDF** Coordinate System#

## Origin Point, Point Size and Y-Axis#

In **PDF**, the origin (for example: `(0, 0)`

) of a page is located at its **bottom-left point**. In **MuPDF**, the origin of a page is located at its **top-left point**.

Note

The exact x,y coordinate space for origin may not be `0,0`

and is defined by “CropBox” - thus “bottom left” is derived from what is defined there.

Important

The rotation of the page affects the PDF coordinate space orientation.

### Point Size#

Coordinates are float numbers and measured in **points**, where:

**The default is one point equals 1/72 inches**.**Is defined by the “UserUnit” property**.

### Positioning objects#

When working with positioning objects, we should appreciate this coordinate system.

For example:

```
let rectangle = [0,0,200,200]
```

Results in:

### Coordinate space and `PDFObject`

#

In exception to using the **MuPDF** coordinate space, if we are dealing *directly* with `PDFObject`

streams then we are using the **PDF** coordinate space.

Therefore if we doing something low-level like adding a content stream to a `PDFObject`

, for example:

```
var extra_contents = document.addStream("q 200 0 0 200 10 10 cm /Image1 Do Q", null)
```

Then in this case we are working in the **PDF** coordinate space with the origin Y-axis at the bottom left.

Note

To explain the syntax behind `"q 200 0 0 200 10 10 cm /Image1 Do Q"`

this is **Adobe PDF** syntax for referencing, sizing and positioning an image and can be explained as follows:

```
q % Save graphics state
200 0 0 200 10 10 cm % Translate
/Image1 Do % Paintimage
Q % Restore graphics state
```

For more see page 337 of the Adobe PDF Reference Guide.

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