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Adafruit Light Painting with Pi
# Light painting / POV demo for Raspberry Pi using
# Adafruit Digital Addressable RGB LED flex strip.
# ---->
import RPi.GPIO as GPIO, Image, time
# Configurable values
filename = "hello.png"
dev = "/dev/spidev0.0"
# Open SPI device, load image in RGB format and get dimensions:
spidev = file(dev, "wb")
print "Loading..."
img ="RGB")
pixels = img.load()
width = img.size[0]
height = img.size[1]
print "%dx%d pixels" % img.size
# To do: add resize here if image is not desired height
# Calculate gamma correction table. This includes
# LPD8806-specific conversion (7-bit color w/high bit set).
gamma = bytearray(256)
for i in range(256):
gamma[i] = 0x80 | int(pow(float(i) / 255.0, 2.5) * 127.0 + 0.5)
# Create list of bytearrays, one for each column of image.
# R, G, B byte per pixel, plus extra '0' byte at end for latch.
print "Allocating..."
column = [0 for x in range(width)]
for x in range(width):
column[x] = bytearray(height * 3 + 1)
# Convert 8-bit RGB image into column-wise GRB bytearray list.
print "Converting..."
for x in range(width):
for y in range(height):
value = pixels[x, y]
y3 = y * 3
column[x][y3] = gamma[value[1]]
column[x][y3 + 1] = gamma[value[0]]
column[x][y3 + 2] = gamma[value[2]]
# Then it's a trivial matter of writing each column to the SPI port.
print "Displaying..."
while True:
for x in range(width):
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DanyN3n3 commented Dec 11, 2014


I have a problem with the code, I have a 60 RGB Strip what do I need to modify to make the code work with my ws2812b led strip? I tried to change the image in the program but it doesn't work. It is only lighting up 4 led's, the first 3 are white and the forth is yellow.

Thank you in advance for your response

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gingerman commented Feb 8, 2015

Hi DannyN3n3,

Good luck, I have a WS2801 strip, which does not work on the PI.
However it does work with my Arduino perfectly, although I need more memory really to load in longer images ( I could probably do it with my Arduino actually ).



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