SHR-NTSC/ntsc-160.py
2017-07-20 14:33:07 -07:00

175 lines
5.3 KiB
Python

import pygame, math, sys
from pygame.locals import *
from PIL import Image
WIDTH = 160
HEIGHT = 200
DEG_PER_CIRCLE = 360
DEG_TO_RAD = math.pi*2/DEG_PER_CIRCLE
UMAX = 0.436
VMAX = 0.615
ntscRGB = [[(0, 0, 0) for y in xrange(4)] for p in xrange(32)]
ntscPixel = [[(0, 0, 0)] for m in xrange(8)]
shrPixels = []
ntscPrev = (0, 0, 0)
def yuv2rgb(y, u, v):
u *= UMAX
v *= VMAX
r = max(0.0, y + 1.14 * v)
g = max(0.0, y - 0.395 * u - 0.581 * v)
b = max(0.0, y + 2.033 * u)
return (r, g, b)
def luv2rgb(y, u, v):
r = max(0.0, y + v)
g = max(0.0, y - 0.707 * u - 0.707 * v)
b = max(0.0, y + u)
return (r, g, b)
def ntscInitRGB(angle):
YScale = [0.0, 0.25, 0.50, 1.0]#[0.0, 0.3334, 0.6667, 1.0]
redSum = 0.0
grnSum = 0.0
bluSum = 0.0
rgb = []
for pix in xrange(32):
#
# U, V for this chroma angle
#
u = math.cos(angle * DEG_TO_RAD)
v = math.sin(angle * DEG_TO_RAD)
#
# Calculate and NTSC RGB for this SHR pixel
#
red, grn, blu = luv2rgb(1.0, u, v)
redSum += red
grnSum += grn
bluSum += blu
rgb.append((red, grn, blu))
#
# Next NTSC chroma pixel
#
angle = angle - 78.75
if angle > 360.0:
angle -= 360.0
if angle < 0.0:
angle += 360.0
#
# Normalize the RGB values of each NTSC pixel component so they add up to white
#
redScale = 255.0 * 7.0 / redSum
grnScale = 255.0 * 7.0 / grnSum
bluScale = 255.0 * 7.0 / bluSum
for lum in xrange(4):
for pix in xrange(len(rgb)):
ntscRGB[pix][lum] = (min(255,int(rgb[pix][0]*redScale*YScale[lum])), min(255,int(rgb[pix][1]*grnScale*YScale[lum])), min(255,int(rgb[pix][2]*bluScale*YScale[lum])))
def lumInc(seq):
s = 0
seq[s] += 1
while seq[s] == 4:
seq[s] = 0
s += 1
if s == len(seq):
return False
seq[s] += 1
return True
def ntscInitPixels():
#
# NTSC pixel mapping to SHR range
#
for pix8 in xrange(8):
shrpix = [0 for p in xrange(4)]
while lumInc(shrpix):
red = 0
grn = 0
blu = 0
for s in xrange(len(shrpix)):
red += ntscRGB[pix8*4+s][shrpix[s]][0]
grn += ntscRGB[pix8*4+s][shrpix[s]][1]
blu += ntscRGB[pix8*4+s][shrpix[s]][2]
ntscPixel[pix8].append((red, grn, blu))
def ntscMapRGB(rgb, x):
global shrPixels
global ntscPrev
pix8 = x % 8
if pix8 == 0:
shrPixels = [0 for n in xrange(32)]
#
# Adjust source color based on reduced destination precision
#
redMatch = max(0,int(rgb[0] - ntscPrev[0] * 0.57))
grnMatch = max(0,int(rgb[1] - ntscPrev[1] * 0.57))
bluMatch = max(0,int(rgb[2] - ntscPrev[2] * 0.57))
#
# Look for best RGB match
#
nearest = 195075
nBest = 0
for n in xrange(len(ntscPixel[pix8])):
red = redMatch - ntscPixel[pix8][n][0]
grn = grnMatch - ntscPixel[pix8][n][1]
blu = bluMatch - ntscPixel[pix8][n][2]
dist = red*red + grn*grn + blu*blu
if dist < nearest:
nearest = dist
nBest = n
#
# Update ouput list
#
rgbBest = ntscPixel[pix8][nBest]
#
# Convert to SHR pixels
#
for n in xrange(4):
shr = nBest & 0x03
shrPixels[pix8*4 + n] = shr
nBest >>= 2
#
# Save last pixel
#
ntscPrev = ntscRGB[(x*4 + 3) & 0x1F][shr]
#
# Output SHR pixels for assembly
#
if pix8 == 7:
print '\t!BYTE\t$%02X, ' % ((shrPixels[0] << 6) | (shrPixels[1] << 4) | (shrPixels[2] << 2) | shrPixels[3]),
print '$%02X, ' % ((shrPixels[4] << 6) | (shrPixels[5] << 4) | (shrPixels[6] << 2) | shrPixels[7]),
print '$%02X, ' % ((shrPixels[8] << 6) | (shrPixels[9] << 4) | (shrPixels[10] << 2) | shrPixels[11]),
print '$%02X, ' % ((shrPixels[12] << 6) | (shrPixels[13] << 4) | (shrPixels[14] << 2) | shrPixels[15]),
print '$%02X, ' % ((shrPixels[16] << 6) | (shrPixels[17] << 4) | (shrPixels[18] << 2) | shrPixels[19]),
print '$%02X, ' % ((shrPixels[20] << 6) | (shrPixels[21] << 4) | (shrPixels[22] << 2) | shrPixels[23]),
print '$%02X, ' % ((shrPixels[24] << 6) | (shrPixels[25] << 4) | (shrPixels[26] << 2) | shrPixels[27]),
print '$%02X' % ((shrPixels[28] << 6) | (shrPixels[29] << 4) | (shrPixels[30] << 2) | shrPixels[31])
return rgbBest
def displayBars():
for bar in xrange(32):
for lum in xrange(4):
surface.fill(ntscRGB[bar][lum], pygame.Rect(bar * 5, lum*50, 5, 50))
pygame.display.flip()
if len(sys.argv) > 1:
imagefile = sys.argv[1]
else:
imagefile = "image.jpg"
image = Image.open(imagefile)
if image.size[0] <> WIDTH or image.size[1] <> HEIGHT:
image = image.resize((WIDTH, HEIGHT), Image.ANTIALIAS)
pygame.init()
surface = pygame.display.set_mode((WIDTH,HEIGHT))
surfpix = pygame.PixelArray(surface)
ntscInitRGB(103.0)
ntscInitPixels()
displayBars()
for y in xrange(HEIGHT):
print '; scanline: ', y
for x in xrange(WIDTH):
surfpix[x][y] = ntscMapRGB(image.getpixel((x, y)), x)
pygame.display.flip()