import argparse import bz2 import functools import os.path import pickle from typing import Tuple from PIL import Image import numpy as np # TODO: # - only lookahead for 560px # - palette class # - compare to bmp2dhr and a2bestpix def srgb_to_linear_array(a: np.ndarray, gamma=2.4) -> np.ndarray: return np.where(a <= 0.04045, a / 12.92, ((a + 0.055) / 1.055) ** gamma) def linear_to_srgb_array(a: np.ndarray, gamma=2.4) -> np.ndarray: return np.where(a <= 0.0031308, a * 12.92, 1.055 * a ** (1.0 / gamma) - 0.055) def srgb_to_linear(im: np.ndarray) -> np.ndarray: rgb_linear = srgb_to_linear_array(im / 255.0, gamma=2.4) return (np.clip(rgb_linear, 0.0, 1.0) * 255).astype(np.float32) def linear_to_srgb(im: np.ndarray) -> np.ndarray: srgb = linear_to_srgb_array(im / 255.0, gamma=2.4) return (np.clip(srgb, 0.0, 1.0) * 255).astype(np.float32) # Default bmp2dhr palette RGB = { 0: np.array((0, 0, 0)), # Black 8: np.array((148, 12, 125)), # Magenta 4: np.array((99, 77, 0)), # Brown 12: np.array((249, 86, 29)), # Orange 2: np.array((51, 111, 0)), # Dark green 10: np.array((126, 126, 125)), # Grey2 6: np.array((67, 200, 0)), # Green 14: np.array((221, 206, 23)), # Yellow 1: np.array((32, 54, 212)), # Dark blue 9: np.array((188, 55, 255)), # Violet 5: np.array((126, 126, 126)), # Grey1 13: np.array((255, 129, 236)), # Pink 3: np.array((7, 168, 225)), # Med blue 11: np.array((158, 172, 255)), # Light blue 7: np.array((93, 248, 133)), # Aqua 15: np.array((255, 255, 255)), # White } # Maps palette values to screen dots. Note that these are the same as # the binary values in reverse order. DOTS = { 0: (False, False, False, False), 1: (True, False, False, False), 2: (False, True, False, False), 3: (True, True, False, False), 4: (False, False, True, False), 5: (True, False, True, False), 6: (False, True, True, False), 7: (True, True, True, False), 8: (False, False, False, True), 9: (True, False, False, True), 10: (False, True, False, True), 11: (True, True, False, True), 12: (False, False, True, True), 13: (True, False, True, True), 14: (False, True, True, True), 15: (True, True, True, True) } DOTS_TO_4BIT = {} for k, v in DOTS.items(): DOTS_TO_4BIT[v] = k # OpenEmulator sRGB = { 0: np.array((0, 0, 0)), # Black 8: np.array((206, 0, 123)), # Magenta 4: np.array((100, 105, 0)), # Brown 12: np.array((247, 79, 0)), # Orange 2: np.array((0, 153, 0)), # Dark green # XXX RGB values are used as keys in DOTS dict, need to be unique 10: np.array((131, 132, 132)), # Grey2 6: np.array((0, 242, 0)), # Green 14: np.array((216, 220, 0)), # Yellow 1: np.array((21, 0, 248)), # Dark blue 9: np.array((235, 0, 242)), # Violet 5: np.array((140, 140, 140)), # Grey1 # XXX 13: np.array((244, 104, 240)), # Pink 3: np.array((0, 181, 248)), # Med blue 11: np.array((160, 156, 249)), # Light blue 7: np.array((21, 241, 132)), # Aqua 15: np.array((244, 247, 244)), # White } # # Virtual II (sRGB) # sRGB = { # (False, False, False, False): np.array((0, 0, 0)), # Black # (False, False, False, True): np.array((231,36,66)), # Magenta # (False, False, True, False): np.array((154,104,0)), # Brown # (False, False, True, True): np.array((255,124,0)), # Orange # (False, True, False, False): np.array((0,135,45)), # Dark green # (False, True, False, True): np.array((104,104,104)), # Grey2 XXX # (False, True, True, False): np.array((0,222,0)), # Green # (False, True, True, True): np.array((255,252,0)), # Yellow # (True, False, False, False): np.array((1,30,169)), # Dark blue # (True, False, False, True): np.array((230,73,228)), # Violet # (True, False, True, False): np.array((185,185,185)), # Grey1 XXX # (True, False, True, True): np.array((255,171,153)), # Pink # (True, True, False, False): np.array((47,69,255)), # Med blue # (True, True, False, True): np.array((120,187,255)), # Light blue # (True, True, True, False): np.array((83,250,208)), # Aqua # (True, True, True, True): np.array((255, 255, 255)), # White # } RGB = {} for k, v in sRGB.items(): RGB[k] = (np.clip(srgb_to_linear_array(v / 255), 0.0, 1.0) * 255).astype( np.uint8) class ColourDistance: @staticmethod def distance(rgb1: np.ndarray, rgb2: np.ndarray) -> np.ndarray: raise NotImplementedError class CIE2000Distance(ColourDistance): """CIE2000 delta-E distance.""" def __init__(self): with bz2.open("nearest.pickle.bz2", "rb") as f: self._distances = pickle.load(f) assert self._distances.dtype == np.uint8 @staticmethod def _flatten_rgb(rgb): return (rgb[..., 0] << 16) + (rgb[..., 1] << 8) + (rgb[..., 2]) def distance(self, rgb: np.ndarray, bit4: np.ndarray) -> np.ndarray: rgb24 = self._flatten_rgb(np.clip(rgb, 0, 255).astype(np.int)) return self._distances[rgb24, bit4].astype(np.int) class Screen: X_RES = None Y_RES = None X_PIXEL_WIDTH = None def __init__(self): self.main = np.zeros(8192, dtype=np.uint8) self.aux = np.zeros(8192, dtype=np.uint8) @staticmethod def y_to_base_addr(y: int) -> int: """Maps y coordinate to screen memory base address.""" a = y // 64 d = y - 64 * a b = d // 8 c = d - 8 * b return 1024 * c + 128 * b + 40 * a def _image_to_bitmap(self, image: np.ndarray) -> np.ndarray: raise NotImplementedError def pack(self, image: np.ndarray): bitmap = self._image_to_bitmap(image) # The DHGR display encodes 7 pixels across interleaved 4-byte sequences # of AUX and MAIN memory, as follows: # PBBBAAAA PDDCCCCB PFEEEEDD PGGGGFFF # Aux N Main N Aux N+1 Main N+1 (N even) main_col = np.zeros( (self.Y_RES, self.X_RES * self.X_PIXEL_WIDTH // 14), dtype=np.uint8) aux_col = np.zeros( (self.Y_RES, self.X_RES * self.X_PIXEL_WIDTH // 14), dtype=np.uint8) for byte_offset in range(80): column = np.zeros(self.Y_RES, dtype=np.uint8) for bit in range(7): column |= (bitmap[:, 7 * byte_offset + bit].astype( np.uint8) << bit) if byte_offset % 2 == 0: aux_col[:, byte_offset // 2] = column else: main_col[:, (byte_offset - 1) // 2] = column for y in range(self.Y_RES): addr = self.y_to_base_addr(y) self.aux[addr:addr + 40] = aux_col[y, :] self.main[addr:addr + 40] = main_col[y, :] @staticmethod def pixel_palette_options(last_pixel, x: int): raise NotImplementedError class DHGR140Screen(Screen): """DHGR screen ignoring colour fringing, i.e. treating as 140x192x16.""" X_RES = 140 Y_RES = 192 X_PIXEL_WIDTH = 4 def _image_to_bitmap(self, image_4bit: np.ndarray) -> np.ndarray: bitmap = np.zeros( (self.Y_RES, self.X_RES * self.X_PIXEL_WIDTH), dtype=np.bool) for y in range(self.Y_RES): for x in range(self.X_RES): pixel = image_4bit[y, x].item() dots = DOTS[pixel] bitmap[y, x * self.X_PIXEL_WIDTH:( (x + 1) * self.X_PIXEL_WIDTH)] = dots return bitmap @staticmethod def pixel_palette_options(last_pixel_4bit, x: int): return np.array(list(RGB.keys())), np.array(list(RGB.values())) class DHGR560Screen(Screen): """DHGR screen including colour fringing.""" X_RES = 560 Y_RES = 192 X_PIXEL_WIDTH = 1 def _image_to_bitmap(self, image_4bit: np.ndarray) -> np.ndarray: bitmap = np.zeros((self.Y_RES, self.X_RES), dtype=np.bool) for y in range(self.Y_RES): for x in range(self.X_RES): pixel = image_4bit[y, x].item() dots = DOTS[pixel] phase = x % 4 bitmap[y, x] = dots[phase] return bitmap @staticmethod def pixel_palette_options(last_pixel_4bit, x: int): last_dots = DOTS[last_pixel_4bit] other_dots = list(last_dots) other_dots[x % 4] = not other_dots[x % 4] other_dots = tuple(other_dots) other_pixel_4bit = DOTS_TO_4BIT[other_dots] return ( np.array([last_pixel_4bit, other_pixel_4bit]), np.array([RGB[last_pixel_4bit], RGB[other_pixel_4bit]])) class Dither: PATTERN = None ORIGIN = None @functools.lru_cache(None) def x_dither_bounds(self, screen: Screen, x: int): pshape = self.PATTERN.shape el = max(self.ORIGIN[1] - x, 0) er = min(pshape[1], screen.X_RES - 1 - x) xl = x - self.ORIGIN[1] + el xr = x - self.ORIGIN[1] + er return el, er, xl, xr @functools.lru_cache(None) def y_dither_bounds(self, screen: Screen, y: int, one_line=False): pshape = self.PATTERN.shape et = max(self.ORIGIN[0] - y, 0) eb = min(pshape[0], screen.Y_RES - 1 - y) yt = y - self.ORIGIN[0] + et yb = y - self.ORIGIN[0] + eb if one_line: yb = yt + 1 eb = et + 1 return et, eb, yt, yb def apply(self, screen: Screen, image: np.ndarray, x: int, y: int, quant_error: np.ndarray, one_line=False): error = self.PATTERN * quant_error.reshape((1, 1, 3)) el, er, xl, xr = self.x_dither_bounds(screen, x) et, eb, yt, yb = self.y_dither_bounds(screen, y, one_line) # We could avoid clipping here, i.e. allow RGB values to extend beyond # 0..255 to capture a larger range of residual error. This is faster # but seems to reduce image quality. # XXX extend image region to avoid need for boundary box clipping image[yt:yb, xl:xr, :] = np.clip( image[yt:yb, xl:xr, :] + error[et:eb, el:er, :], 0, 255) def apply_one_line(self, screen: Screen, image: np.ndarray, x: int, y: int, quant_error: np.ndarray): error = self.PATTERN[0, :] * quant_error.reshape(1, 3) el, er, xl, xr = self.x_dither_bounds(screen, x) image[y, xl:xr, :] = np.clip( image[y, xl:xr, :] + error[el:er, :], 0, 255) class FloydSteinbergDither(Dither): # 0 * 7 # 3 5 1 PATTERN = np.array(((0, 0, 7), (3, 5, 1)), dtype=np.float32).reshape(2, 3, 1) / np.float(16) # XXX X_ORIGIN since ORIGIN[0] == 0 ORIGIN = (0, 1) class BuckelsDither(Dither): # 0 * 2 1 # 1 2 1 0 # 0 1 0 0 PATTERN = np.array(((0, 0, 2, 1), (1, 2, 1, 0), (0, 1, 0, 0)), dtype=np.float32).reshape(3, 4, 1) / np.float32(8) ORIGIN = (0, 1) class JarvisDither(Dither): # 0 0 X 7 5 # 3 5 7 5 3 # 1 3 5 3 1 PATTERN = np.array(((0, 0, 0, 7, 5), (3, 5, 7, 5, 3), (1, 3, 5, 3, 1)), dtype=np.float32).reshape(3, 5, 1) / np.float32(48) ORIGIN = (0, 2) # XXX needed? def SRGBResize(im, size, filter) -> np.ndarray: # Convert to numpy array of float arr = np.array(im, dtype=np.float32) / 255.0 # Convert sRGB -> linear arr = np.where(arr <= 0.04045, arr / 12.92, ((arr + 0.055) / 1.055) ** 2.4) # Resize using PIL arrOut = np.zeros((size[1], size[0], arr.shape[2])) for i in range(arr.shape[2]): chan = Image.fromarray(arr[:, :, i]) chan = chan.resize(size, filter) arrOut[:, :, i] = np.array(chan).clip(0.0, 1.0) # Convert linear -> sRGB arrOut = np.where(arrOut <= 0.0031308, 12.92 * arrOut, 1.055 * arrOut ** (1.0 / 2.4) - 0.055) arrOut = np.rint(np.clip(arrOut, 0.0, 1.0) * 255.0) return arrOut def open_image(screen: Screen, filename: str) -> np.ndarray: im = Image.open(filename) # TODO: convert to sRGB colour profile explicitly, in case it has some other # profile already. if im.mode != "RGB": im = im.convert("RGB") return srgb_to_linear( SRGBResize(im, (screen.X_RES, screen.Y_RES), Image.LANCZOS)) @functools.lru_cache(None) def lookahead_options(screen, lookahead, last_pixel_4bit, x): options_4bit = np.empty((2 ** lookahead, lookahead), dtype=np.uint8) options_rgb = np.empty((2 ** lookahead, lookahead, 3), dtype=np.float32) for i in range(2 ** lookahead): output_pixel_4bit = last_pixel_4bit for j in range(lookahead): xx = x + j palette_choices_4bit, palette_choices_rgb = \ screen.pixel_palette_options(output_pixel_4bit, xx) output_pixel_4bit = palette_choices_4bit[(i & (1 << j)) >> j] output_pixel_rgb = np.array( palette_choices_rgb[(i & (1 << j)) >> j]) # XXX copy options_4bit[i, j] = output_pixel_4bit options_rgb[i, j, :] = np.copy(output_pixel_rgb) return options_4bit, options_rgb def dither_lookahead( screen: Screen, image_rgb: np.ndarray, dither: Dither, differ: ColourDistance, x, y, last_pixel_4bit, lookahead ) -> Tuple[np.ndarray, np.ndarray]: el, er, xl, xr = dither.x_dither_bounds(screen, x) # X coord value of larger of dither bounding box or lookahead horizon xxr = min(max(x + lookahead, xr), screen.X_RES) # copies of input pixels so we can dither in bulk # Leave enough space so we can dither the last of our lookahead pixels lah_image_rgb = np.zeros( (2 ** lookahead, lookahead + xr - xl, 3), dtype=np.float32) lah_image_rgb[:, 0:xxr - x, :] = np.copy(image_rgb[y, x:xxr, :]) options_4bit, options_rgb = lookahead_options( screen, lookahead, last_pixel_4bit, x % 4) for i in range(xxr - x): # options_rgb choices are fixed, but we can still distribute # quantization error from having made these choices, in order to compute # the total error input_pixels = np.copy(lah_image_rgb[:, i, :]) output_pixels = options_rgb[:, i, :] quant_error = input_pixels - output_pixels # Don't update the input at position x (since we've already chosen # fixed outputs), but do propagate quantization errors to positions >x # so we can compensate for how good/bad these choices were # XXX vectorize for j in range(2 ** lookahead): # print(quant_error[j]) dither.apply_one_line(screen, lah_image_rgb[j, :, :].reshape(1, -1, 3), i, 0, quant_error[j]) error = differ.distance(np.clip( lah_image_rgb[:, 0:lookahead, :], 0, 255), options_4bit) # print(error.dtype) # print(lah_image_lab) # print("error=", error) # print(error.shape) total_error = np.sum(np.power(error, 2), axis=1) # print("total_error=", total_error) best = np.argmin(total_error) # print("best=", best) # print("best 4bit=", options_4bit[best, 0].item(), options_rgb[best, 0, :]) return options_4bit[best, 0].item(), options_rgb[best, 0, :] def dither_image( screen: Screen, image_rgb: np.ndarray, dither: Dither, differ: ColourDistance, lookahead) -> Tuple[np.ndarray, np.ndarray]: image_4bit = np.empty( (image_rgb.shape[0], image_rgb.shape[1]), dtype=np.uint8) # pattern = dither.PATTERN for y in range(screen.Y_RES): print(y) output_pixel_4bit = np.uint8(0) for x in range(screen.X_RES): # for x in range(pattern.ORIGIN[1], pattern.ORIGIN[1] + screen.X_RES): input_pixel_rgb = np.copy(image_rgb[y, x, :]) output_pixel_4bit, output_pixel_rgb = \ dither_lookahead(screen, image_rgb, dither, differ, x, y, output_pixel_4bit, lookahead) image_4bit[y, x] = output_pixel_4bit image_rgb[y, x, :] = output_pixel_rgb quant_error = input_pixel_rgb - output_pixel_rgb dither.apply(screen, image_rgb, x, y, quant_error) return image_4bit, image_rgb def main(): parser = argparse.ArgumentParser() parser.add_argument("input", type=str, help="Input file to process") parser.add_argument("output", type=str, help="Output file for ") parser.add_argument( "--lookahead", type=int, default=4, help=("How many pixels to look ahead to compensate for NTSC colour " "artifacts.")) args = parser.parse_args() # screen = DHGR140Screen() screen = DHGR560Screen() image = open_image(screen, args.input) # image_rgb.show() # dither = FloydSteinbergDither() # dither = BuckelsDither() dither = JarvisDither() differ = CIE2000Distance() output_4bit, output_rgb = dither_image(screen, image, dither, differ, lookahead=args.lookahead) screen.pack(output_4bit) out_image = Image.fromarray(linear_to_srgb(output_rgb).astype(np.uint8)) outfile = os.path.join(os.path.splitext(args.output)[0] + ".png") out_image.save(outfile, "PNG") out_image.show(title=outfile) # bitmap = Image.fromarray(screen.bitmap.astype('uint8') * 255) with open(args.output, "wb") as f: f.write(bytes(screen.main)) f.write(bytes(screen.aux)) if __name__ == "__main__": main()