The np_pixels[] array contains the values for all the pixels in the Py5Graphics drawing surface.


example picture for np_pixels[]

def setup():
    g = py5.create_graphics(80, 80)
    g.rect(10, 10, 60, 60)
    g.np_pixels[:, 40:, 1:] = [255, 0, 0]
    py5.image(g, 10, 10)


The np_pixels[] array contains the values for all the pixels in the Py5Graphics drawing surface. Unlike the one dimensional array Py5Graphics.pixels[], the np_pixels[] array organizes the color data in a 3 dimensional numpy array. The size of the array’s dimensions are defined by the size of the Py5Graphics drawing surface. The first dimension is the height, the second is the width, and the third represents the color channels. The color channels are ordered alpha, red, green, blue (ARGB). Every value in np_pixels[] is an integer between 0 and 255.

This numpy array is very similar to the image arrays used by other popular Python image libraries, but note that some of them like opencv will by default order the color channels as RGBA.

When the pixel density is set to higher than 1 with the Py5Graphics.pixel_density function, the size of np_pixels[]’s height and width dimensions will change. See the reference for Py5Graphics.pixel_width or Py5Graphics.pixel_height for more information. Nothing about np_pixels[] will change as a result of calls to Py5Graphics.color_mode().

Much like the Py5Graphics.pixels[] array, there are load and update methods that must be called before and after making changes to the data in np_pixels[]. Before accessing np_pixels[], the data must be loaded with the Py5Graphics.load_np_pixels() method. If this is not done, np_pixels will be equal to None and your code will likely result in Python exceptions. After np_pixels[] has been modified, the Py5Graphics.update_np_pixels() method must be called to update the content of the Py5Graphics drawing surface.

Working with Py5Graphics.np_pixels[] can only be done between calls to Py5Graphics.begin_draw() and Py5Graphics.end_draw().

To set the entire contents of np_pixels[] to the contents of another properly sized numpy array, consider using Py5Graphics.set_np_pixels().

Look at the online “Numpy, Arrays, and Images” Python Ecosystem Integration tutorial for more information about how to make best use of np_pixels[].

This field is the same as np_pixels[] but linked to a Py5Graphics object.

Updated on December 25, 2023 17:02:43pm UTC