From b29c494715fa1e1e43d19a5429d11aedb9e29593 Mon Sep 17 00:00:00 2001 From: Lephenixnoir Date: Sat, 14 May 2022 12:38:52 +0100 Subject: [PATCH] fxconv: rewrite image converter, forcing alpha value --- fxconv/fxconv.py | 396 +++++++++++++++++++---------------------------- 1 file changed, 161 insertions(+), 235 deletions(-) diff --git a/fxconv/fxconv.py b/fxconv/fxconv.py index d686b70..423c042 100644 --- a/fxconv/fxconv.py +++ b/fxconv/fxconv.py @@ -90,40 +90,50 @@ FX_PROFILES = [ # fx-CG 50 profiles class CgProfile: - def __init__(self, id, name, alpha): - """ - Construct a CgProfile object. - * [id] is the profile ID in bopti - * [name] is the profile name as found in the specification key - * [alpha] is True if this profile supports alpha, False otherwise - """ - + def __init__(self, id, depth, names, alpha=None, palette=None): + # Numerical ID self.id = id - self.name = name - self.supports_alpha = alpha + # Name for printing + self.names = names + # Bit depth + self.depth = depth + # Whether the profile has alpha + self.has_alpha = (alpha is not None) + # Alpha value (None has_alpha == False) + self.alpha = alpha + # Whether the profile is indexed + self.is_indexed = (palette is not None) + + if palette is not None: + # Palette base value (skipping the alpha value) + self.palette_base = palette[0] + # Color count (indices are always 0..color_count-1, wraps around) + self.color_count = palette[1] + # Whether to trim the palette to a minimal length + self.trim_palette = palette[2] @staticmethod def find(name): """Find a profile by name.""" for profile in CG_PROFILES: - if profile.name == name: + if name in profile.names: return profile return None +IMAGE_RGB16 = 0 +IMAGE_P8 = 1 +IMAGE_P4 = 2 + CG_PROFILES = [ # 16-bit RGB565 and RGB565 with alpha - CgProfile(0x0, "rgb565", False), - CgProfile(0x1, "rgb565a", True), + CgProfile(0x0, IMAGE_RGB16, ["rgb565", "r5g6b5"]), + CgProfile(0x1, IMAGE_RGB16, ["rgb565a", "r5g6b5a"], alpha=0x0001), # 8-bit palette for RGB565 and RGB565A - CgProfile(0x4, "p8_rgb565", False), - CgProfile(0x5, "p8_rgb565a", True), + CgProfile(0x4, IMAGE_P8, "p8_rgb565", palette=(0x80,256,True)), + CgProfile(0x5, IMAGE_P8, "p8_rgb565a", alpha=0x80, palette=(0x81,256,True)), # 4-bit palette for RGB565 and RGB565A - CgProfile(0x6, "p4_rgb565", False), - CgProfile(0x3, "p4_rgb565a", True), - - # Original names for RGB565 and RGB565A - CgProfile(0x0, "r5g6b5", False), - CgProfile(0x1, "r5g6b5a", True), + CgProfile(0x6, IMAGE_P4, "p4_rgb565", palette=(0,16,False)), + CgProfile(0x3, IMAGE_P4, "p4_rgb565a", alpha=0, palette=(1,16,False)), ] # Libimg flags @@ -511,7 +521,19 @@ def _image_project(img, f): # Image conversion for fx-CG 50 # +def image_has_alpha(img): + # Convert the alpha channel to 1-bit; check if there are transparent pixels + try: + alpha_channel = img.getchannel("A").convert("1", dither=Image.NONE) + alpha_levels = { t[1]: t[0] for t in alpha_channel.getcolors() } + return 0 in alpha_levels + except ValueError: + return False + def convert_bopti_cg(input, params): + return convert_image_cg(input, params) + +def convert_image_cg(input, params): if isinstance(input, Image.Image): img = input.copy() else: @@ -523,68 +545,48 @@ def convert_bopti_cg(input, params): area = Area(params.get("area", {}), img) img = img.crop(area.tuple()) - # If no profile is specified, fall back to rgb565 or rgb565a later on - name = params.get("profile", None) - if name is not None: - profile = CgProfile.find(name) + img = img.convert("RGBA") - if name in ["r5g6b5", "r5g6b5a", "rgb565", "rgb565a", None]: - # Encode the image into the 16-bit format - encoded, stride, alpha = r5g6b5(img) + #--- + # Format selection + #--- - if name is None: - name = "rgb565" if alpha is None else "rgb565a" - profile = CgProfile.find(name) + format_name = params.get("profile", "") + has_alpha = image_has_alpha(img) - color_count = -1 - palette = None + # If no format is specified, select rgb565 or rgb565a + if format_name == "": + format_name = "rgb565a" if has_alpha else "rgb565" + # Similarly, if "p8" or "p4" is specified, select the cheapest variation + elif format_name == "p8": + format_name = "p8_rgb565a" if has_alpha else "p8_rgb565" + elif format_name == "p4": + format_name = "p4_rgb565a" if has_alpha else "p4_rgb565" - elif name.startswith("p"): - force_alpha = name.endswith("_rgb565a") - if name.startswith("p8"): - trim_palette = True - palette_base = 0x80 - color_count = 256 - elif name.startswith("p4"): - trim_palette = False - palette_base = 0x00 - color_count = 16 - else: - raise FxconvError(f"unknown palette format {profile}") + # Otherwise, just use the format as specified + format = CgProfile.find(format_name) + if format is None: + raise FxconvError(f"unknown image format '{format_name}") - # Encode the image into 16-bit with a palette of 16 or 256 entries - encoded, stride, palette, alpha = r5g6b5(img, color_count=color_count, - trim_palette=trim_palette, palette_base=palette_base, - force_alpha=force_alpha) + # Check that we have transparency support if we need it + if has_alpha and not format.has_alpha: + raise FxconvError(f"'{input}' has transparency, which {format_name} "+ + "doesn't support") - color_count = len(palette) // 2 + #--- + # Structure generation + #--- - else: - raise FxconvError(f"unknown color profile '{name}'") - - # Resolve "p8" and "p4" to their optimal variation - if name == "p8": - name = "p8_rgb565" if alpha is None else "p8_rgb565a" - profile = CgProfile.find(name) - elif name == "p4": - name = "p4_rgb565" if alpha is None else "p4_rgb565a" - profile = CgProfile.find(name) - - if alpha is not None and not profile.supports_alpha: - raise FxconvError(f"'{input}' has transparency; use rgb565a, " + - "p8_rgb565a or p4_rgb565a") - - if len(encoded) % 4 != 0: - encoded += bytes(4 - (len(encoded) % 4)) + data, stride, palette, color_count = image_encode(img, format) o = ObjectData() - o += u8(profile.id) + o += u8(format.id) o += u8(3) # DATA_RO, PALETTE_RO - o += u16(alpha if alpha is not None else 0xffff) + o += u16(format.alpha if format.alpha is not None else 0xffff) o += u16(img.width) o += u16(img.height) o += u32(stride) - o += ref(encoded, padding=4) + o += ref(data, padding=4) o += u32(color_count) if palette is None: o += u32(0) @@ -856,7 +858,8 @@ def convert_libimg_cg(input, params): img = img.crop(area.tuple()) # Encode the image into 16-bit format and force the alpha to 0x0001 - encoded, stride, alpha = r5g6b5(img, force_alpha=(0x0001,0x0000)) + format = CgProfile.find("rgb565a") + encoded, stride, palette, color_count = image_encode(img, format) o = ObjectData() o += u16(img.width) + u16(img.height) @@ -942,218 +945,141 @@ def quantize(img, dither=False): return img -def r5g6b5(img, color_count=0, trim_palette=False, palette_base=0, - force_alpha=None): +def image_encode(img, format): """ - Convert a PIL.Image.Image into an RGB565 byte stream. If there are - transparent pixels, chooses a color to implement alpha and replaces them - with this color. + Encodes a PIL.Image.Image into one of the fx-CG image formats. The color + depth is either RGB16, P8 or P4, with various transparency settings and + palette encodings. - When color_count=0, converts the image to 16-bit; returns a bytearray of - pixel data, the byte stride, and the automatically-chosen alpha value (or - None). - - * If force_alpha is a pair (value, replacement), then the alpha is forced - to be the indicated value, and any natural occurrence of the value is - substituted with the replacement. - - When color_count>0, if should be either 16 or 256. The image is encoded - with a palette of that size. Returns the converted image as a bytearray, - the byte stride, the palette as a bytearray, and the alpha value (None if - there were no transparent pixels). - - * If trim_palette is set, the palette bytearray is trimmed so that only - used entries are set (this does not include alpha, which is at the end). - * If palette_base is provided, palette entries will be numbered starting - from that value, wrapping around modulo color_count. - * If force_alpha=True, an index will be reserved for alpha even if no pixel - is transparent in the source image. + Returns 4 values: + * data: A bytearray containing the encoded image data + * stride: The byte stride of the data array + * palette: A bytearray containing the encoded palette (None if not indexed) + * color_count: Number of colors in the palette (-1 if not indexed) """ - def rgb24to16(rgb24): - r, g, b = rgb24 - r = (r & 0xff) >> 3 - g = (g & 0xff) >> 2 - b = (b & 0xff) >> 3 - return (r << 11) | (g << 5) | b - #--- - # Initial image transforms - # Separate the alpha channel and generate a first palette. + # Separate the alpha channel #--- # Save the alpha channel and make it 1-bit. If there are transparent # pixels, set has_alpha=True and record the alpha channel in alpha_pixels. - try: + if format.has_alpha: alpha_channel = img.getchannel("A").convert("1", dither=Image.NONE) - alpha_levels = { t[1]: t[0] for t in alpha_channel.getcolors() } - has_alpha = 0 in alpha_levels - replacement = None + else: + alpha_channel = Image.new("1", img.size, 1) - if has_alpha: - alpha_pixels = alpha_channel.load() - - except ValueError: - has_alpha = False - - # Convert the input image to RGB + alpha_pixels = alpha_channel.load() img = img.convert("RGB") - # Transparent pixels also have values on the RGB channels, so they use up a - # palette entry (in indexed mode) or possible alpha value (in 16-bit mode) - # even though their color is unused. Replace them with a non-transparent - # color used elsewhere in the image to avoid that. - if has_alpha: - nontransparent_pixels = { (x,y) - for x in range(img.width) for y in range(img.height) - if alpha_pixels[x,y] > 0 } + # Transparent pixels have random values on the RGB channels, causing them + # to use up palette entries during quantization. To avoid that, set their + # RGB data to a color used somewhere else in the image. + pixels = img.load() + bg_color = next((pixels[x,y] + for x in range(img.width) for y in range(img.height) + if alpha_pixels[x,y] > 0), + (0,0,0)) - if nontransparent_pixels: - x0, y0 = nontransparent_pixels.pop() - pixels = img.load() + for y in range(img.height): + for x in range(img.width): + if alpha_pixels[x,y] == 0: + pixels[x,y] = bg_color - for y in range(img.height): - for x in range(img.width): - if alpha_pixels[x,y] == 0: - pixels[x,y] = pixels[x0,y0] + #--- + # Quantize to generate a palette + #--- - # In indexed mode, generate a specific palette - if color_count: - palette_max_size = color_count - int(has_alpha or force_alpha == True) + if format.is_indexed: + palette_max_size = format.color_count - int(format.has_alpha) img = img.convert("P", dither=Image.NONE, palette=Image.ADAPTIVE, colors=palette_max_size) - # Format for the first palette is a list of N triplets where N is the - # number of used opaque colors; obviously N <= palette_max_size - # Note: sometimes colors are not numbered 0..N-1, so we take the max - # value rather than len(img.getcolors()); we don't try to remap indices + # The palette format is a list of N triplets where N includes both the + # opaque colors we just generated and an alpha color. Sometimes colors + # after img.convert() are not numbered 0..N-1, so take the max. pixels = img.load() N = 1 + max(pixels[x,y] - for y in range(img.height) - for x in range(img.width)) - palette1 = img.getpalette()[:3*N] - palette1 = list(zip(palette1[::3], palette1[1::3], palette1[2::3])) + for y in range(img.height) for x in range(img.width)) + + palette = img.getpalette()[:3*N] + palette = list(zip(palette[::3], palette[1::3], palette[2::3])) + + # For formats with transparency, make the transparent color consistent + if format.has_alpha: + N += 1 + palette = [(255, 0, 255)] + palette + + # Also keep track of how to remap indices from the values generated by + # img.convert() into the palette, which is shifted by 1 due to alpha + # and also starts at format.palette_base. Note: format.palette_base + # already starts 1 value later for formats with alpha. + palette_map = [(format.palette_base + i) % format.color_count + for i in range(N)] else: - pixels = img.load() + px = img.load() #--- - # Alpha encoding - # Find a value to encode transparency and map it into palettes. + # Encode data into a bytearray #--- - # RGB565A with fixed alpha value (fi. alpha=0x0001 in libimg) - if color_count == 0 and force_alpha is not None: - alpha, replacement = force_alpha + def rgb24to16(rgb): + r = (rgb[0] & 0xff) >> 3 + g = (rgb[1] & 0xff) >> 2 + b = (rgb[2] & 0xff) >> 3 + return (r << 11) | (g << 5) | b - # For palettes, anything works; use the next value - elif color_count > 0 and (has_alpha or force_alpha == True): - alpha = N - - # Find an unused RGB565 value and keep the encoding to 16-bit - elif has_alpha: - colormap = { rgb24to16(pixels[x, y]) - for x in range(img.width) for y in range(img.height) - if alpha_pixels[x, y] > 0 } - - available = set(range(65536)) - colormap - - if not available: - raise FxconvError("image uses all 65536 colors and alpha") - alpha = available.pop() - - # No transparency in the image - else: - alpha = None - - # Function to encode with alpha support in RGB565 - def alpha_encoding(color, a): - if a > 0: # pixel is not transparent - return color if color != alpha else replacement - else: - return alpha - - # In palette formats, rearrange the palette to account for modulo numbering - # and trim the palette if needed - - if color_count > 0: - total = len(palette1) + int(has_alpha or force_alpha == True) - # The palette_map list associates to indices into palette1, the pixel - # value in the data array (which starts at palette_base) - palette_map = [(palette_base + i) % color_count for i in range(total)] - - #--- - # Image encoding - # Create byte arrays with pixel data and palette data - #--- - - stride = 0 - - if not color_count: - # In RGB16, preserve alignment between rows + if format.depth == IMAGE_RGB16: + # Preserve alignment between rows by padding to 4 bytes stride = (img.width + 1) // 2 * 4 size = stride * img.height * 2 - elif color_count == 256: - # No constraint in P8 + elif format.depth == IMAGE_P8: size = img.width * img.height stride = img.width - elif color_count == 16: - # In P4, pad whole bytes + elif format.depth == IMAGE_P4: + # Pad whole bytes stride = (img.width + 1) // 2 size = stride * img.height - # Result of encoding - encoded = bytearray(size) - # Offset into the array - offset = 0 + # Encode the pixel data + data = bytearray(size) for y in range(img.height): for x in range(img.width): - a = alpha_pixels[x, y] if has_alpha else 255 + a = alpha_pixels[x,y] - if not color_count: - c = alpha_encoding(rgb24to16(pixels[x, y]), a) + if format.depth == IMAGE_RGB16: + # If c lands on the alpha value, flip its lowest bit + c = rgb24to16(pixels[x, y]) + c = format.alpha if (a == 0) else c ^ (c == format.alpha) offset = (stride * y) + x * 2 - encoded[offset:offset+2] = u16(c) + data[offset:offset+2] = u16(c) - elif color_count == 16: - c = palette_map[pixels[x, y] if a > 0 else alpha] + elif format.depth == IMAGE_P8: + c = palette_map[pixels[x, y]] if a > 0 else format.alpha + offset = (stride * y) + x + data[offset] = c - # Select either the 4 MSb or 4 LSb of the current byte + elif format.depth == IMAGE_P4: + c = palette_map[pixels[x, y]] if a > 0 else format.alpha + offset = (stride * y) + (x // 2) if x % 2 == 0: - encoded[offset] |= (c << 4) + data[offset] |= (c << 4) else: - encoded[offset] |= c + data[offset] |= c - offset += (x % 2 == 1) or (x == img.width - 1) + # Encode the palette - elif color_count == 256: - c = palette_map[pixels[x, y] if a > 0 else alpha] - encoded[offset] = c - offset += 1 - - # Encode the palette as R5G6B5 - - if color_count > 0: - if trim_palette: - encoded_palette = bytearray(2 * len(palette_map)) - else: - encoded_palette = bytearray(2 * color_count) - - for i in range(len(palette1)): - encoded_palette[2*i:2*i+2] = u16(rgb24to16(palette1[i])) - - #--- - # Outro - #--- - - if color_count > 0: - if alpha is not None: - alpha = palette_map[alpha] - return encoded, stride, encoded_palette, alpha + if format.is_indexed: + N = N if format.trim_palette else format.color_count + encoded_palette = bytearray(2 * N) + for i, rgb24 in enumerate(palette): + encoded_palette[2*i:2*i+2] = u16(rgb24to16(rgb24)) + return data, stride, encoded_palette, N else: - return encoded, stride, alpha + return data, stride, None, -1 def convert(input, params, target, output=None, model=None, custom=None): """