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3x faster greyscale images using all 4 channels.

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antirez
2024-03-16 17:32:12 +01:00
parent 80a682aa08
commit 978e344ce7
1 changed files with 69 additions and 25 deletions
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94
uc8151.py
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@@ -560,21 +560,34 @@ class UC8151:
# Before calling this function, the framebuffer must be already with
# all the bits set to 0. Just call fb.fill(0) to do this quickly.
@micropython.viper
def set_pixels_for_greyscale(self, grey:ptr8, fb:ptr8, width:int, height:int) -> int:
def set_pixels_for_greyscale(self, grey:ptr8, fb1:ptr8, fb2:ptr8, width:int, height:int) -> int:
count = int(width*height)
anypixel = int(0)
for i in range(count):
if grey[i] > 0:
# Pixel that reached level "1" are the only ones at the
# current grey level we want to set.
if grey[i] == 1:
byte = i >> 3
bit = 1 << (7-(i&7))
fb[byte] |= bit
anypixel = 1
# We decrement all the pixels not yet at 0, so successive
# level of greys will appear at value "1".
grey[i] -= 1
# Pixel that reached level "1" are the only ones at the
# current grey level we want to set.
byte = i >> 3
bit = 1 << (7-(i&7))
if grey[i] == 1: # WW condition
anypixel = 1
pass # Both bits at 0
elif grey[i] == 2: # BB condition
anypixel = 1
fb1[byte] |= bit
fb2[byte] |= bit
elif grey[i] == 3: # WB condition
anypixel = 1
fb1[byte] |= bit
else: # BW condition, pixels not touched.
fb2[byte] |= bit
# We decrement all the pixels not yet at 0, so successive
# level of greys will appear at values 1, 2, 3.
if grey[i] > 3:
grey[i] -= 3
else:
grey[i] = 0
return anypixel
def load_greyscale_image(self,filename):
@@ -582,9 +595,9 @@ class UC8151:
# 1. How many frames it takes for a pixel to reach full black?
# 2. How many greys we want to generate?
greyscale = 32 # Can't be more than 32. Try 32, 16, 8, 4.
greyscale = 32 # Can't be more than 32. Try 32, 16, 8, 4.
frames_to_black = 32
# Read image data.
f = open(filename,"rb")
f.read(4)
@@ -599,39 +612,69 @@ class UC8151:
# Nothing to do for white pixels or already black pixels.
# Set an empty LUT.
LUT = bytearray(42)
self.write(CMD_LUT_BW,LUT)
self.write(CMD_LUT_WW,LUT)
self.write(CMD_LUT_BB,LUT)
VCOM = bytearray(44)
# Now for each level of grey in the image, create a bitmap composed
# only of pixels of that level of grey, and create an ad-hoc LUT
# that polarizes pixels towards black for an amount of time (frames)
# proportional to the grey level.
for g in range(greyscale):
for g in range(0,greyscale,3):
self.fb.fill(0)
fb2 = bytearray(self.width*self.height//8)
# Resort to a faster method in Viper to set the pixels for the
# current greyscale level.
anypixel = self.set_pixels_for_greyscale(imgdata,self.raw_fb,self.width,self.height)
anypixel = self.set_pixels_for_greyscale(imgdata,self.raw_fb,fb2,self.width,self.height)
if anypixel:
# Transfer the "old" image, so that for difference
# with the new we transfer via .update() we create
# the four set of conditions (WW, BB, WB, BW) based
# on the difference between the bits in the two
# images.
#
# This is a "fake" update that should not do nothing
# if not to refresh the display status of what was
# previously on the screen, so we set a repeat of 0.
LUT[5] = 1 # Repeat 1 for all
LUT[0] = 0x55 # Go black
LUT[1] = 0 # Zero frames, fake update.
VCOM[1] = LUT[1]
self.write(CMD_LUT_VCOM,VCOM)
self.write(CMD_LUT_WW,LUT)
self.write(CMD_LUT_BB,LUT)
self.write(CMD_LUT_WB,LUT)
self.write(CMD_LUT_BW,LUT)
self.write(CMD_PON) # Power on
self.write(CMD_PTOU) # Partial mode off
self.write(CMD_DTM2,fb2) # Start data transfer
self.write(CMD_DSP) # End of data
self.write(CMD_DRF) # Start refresh cycle.
self.wait_and_switch_off()
# We set the framebuffer with just the pixels of the level
# of grey we are handling in this cycle, so now we apply
# the voltage for a time proportional to this level (see
# the setting of LUT[1], that is the number of frames).
LUT[5] = 1 # Repeat 1 for all
LUT[0] = 0x55 # Go black
LUT[1] = int(frames_to_black/greyscale*(g+1))
self.write(CMD_LUT_WW,LUT)
LUT[1] = int(frames_to_black/greyscale*(g+2))
self.write(CMD_LUT_BB,LUT)
LUT[1] = int(frames_to_black/greyscale*(g+3))
self.write(CMD_LUT_WB,LUT)
LUT[1] = 0 # These pixels will be unaffected, none of them
# is of the three colors handled in this cycle.
LUT[5] = 0
self.write(CMD_LUT_BW,LUT)
# Minimal VCOM LUT to avoid any unneeded wait.
VCOM = bytearray(44)
VCOM[0] = 0 # Already zero, just to make it obvious.
VCOM[1] = LUT[1]
VCOM[1] = int(frames_to_black/greyscale*(g+3))
VCOM[5] = 1
self.write(CMD_LUT_VCOM,VCOM)
print("start update grey level",g)
# Finally update.
self.update(blocking=True)
print("end update")
# Restore a normal LUT based on configured speed.
self.set_waveform_lut()
@@ -643,6 +686,7 @@ if __name__ == "__main__":
spi = SPI(0, baudrate=12000000, phase=0, polarity=0, sck=Pin(18), mosi=Pin(19), miso=Pin(16))
eink = UC8151(spi,cs=17,dc=20,rst=21,busy=26,speed=2,no_flickering=False)
eink.load_greyscale_image("dama.grey")
eink.load_greyscale_image("hopper.grey")
STOP