# Image Coordinate Systems

The conventions below apply to all **eVision** functions and results.

* Pixel coordinates are usually given as integer numbers.
* Some results can use subpixel precision with real (floating point) numbers.
* Some exceptions apply and are documented per library.

## Integer coordinates

* The origin (0,0) of the coordinate system is the upper left pixel of the image.
* The lower right pixel is (width-1, height-1).
  ![image](assets/images/manipulating/image_coordinate_systems_integer.webp)

## Real coordinates

* With floating point (x,y) coordinates, the origin is the upper left corner of the upper left pixel.
* The first pixel area ranges in [0,1[ for X and Y axis.
* Coordinates greater or equal than the width or the height are outside the image.
  ![image](assets/images/manipulating/image_coordinate_systems_float.webp)