The basic operation of images

Coordinates

Get /Set pixel points

We can get the value of a pixel point through image.get_pixel(x, y)

• image.get_pixel(x, y)
  • For grayscale map: return to the grayscale of (x,y)
  • For color map: return to the tuple of (r,g,b) of (x,y)

In the same way can we set the value of a pixel point through image.set_pixel(x, y, pixel).

• image.set_pixel(x, y, pixel)
  • For grayscale map: set the grayscale of (x,y)
  • For color map: set the value of (r,g,b) of (x,y)

For example:

img = sensor.snapshot()
img.get_pixel(10,10)
img.set_pixcel(10,10,(255,0,0))#set the pixel point of which the coordinate is (10,10) as red(255,0,0)

Get the width and height of images

• image.width()
  return to the width of the image(pixel)

• image.height()
  return to the height of the image(pixel)

• image.format()
  return to sensor.GRAYSCALE when it is grayscale map and sensor.RGB565 when color map

• image.size()
  return to the size of the image(byte)

Operation of the image

• image.invert()

Invert, for binary images, means inverting 0(black) to 1(white) and 1(white) to 0(black).

Note: The image can be another object or an image read-in from (bmp/pgm/ppm) documents. In addition, the two images have to be in same size and type (grayscale/color map).

• image.nand(image)
  Execute NAND with another image.

• image.nor(image)
  Execute NOR with another image.

• image.xor(image)
  Execute XOR with another image.

• image.xnor(image)
  Execute XNOR with another image.

• image.difference(image)
  Subtract another image from this image. For example, take negative absolute value to each pixel point in each channel. This function is always used to do mobile detection.