diff --git a/adafruit_imageload/png.py b/adafruit_imageload/png.py old mode 100644 new mode 100755 index 0c5892f..215e313 --- a/adafruit_imageload/png.py +++ b/adafruit_imageload/png.py @@ -28,7 +28,7 @@ import struct import zlib -__version__ = "0.0.0-auto.0" +__version__ = "0.0.0+auto.0" __repo__ = "https://github.com/adafruit/Adafruit_CircuitPython_ImageLoad.git" @@ -106,12 +106,48 @@ def load( # noqa: PLR0912, PLR0915, Too many branches, Too many statements if mode == 3: # indexed bmp = bitmap(width, height, 1 << depth) pixels_per_byte = 8 // depth - src = 1 - src_b = 1 + src = 0 pixmask = (1 << depth) - 1 + line = bytearray(scanline) + prev = bytearray(scanline) for y in range(height): + filter_ = data_bytes[src] + src_b = src + 1 for x in range(0, width, pixels_per_byte): + # relative position on the line + pos = x // pixels_per_byte byte = data_bytes[src_b] + if filter_ == 0: + pass + elif filter_ == 1: # sub + prev_b = line[pos - unit] if pos >= unit else 0 + byte = (byte + prev_b) & 0xFF + elif filter_ == 2: # up + byte = (byte + prev[pos]) & 0xFF + elif filter_ == 3: # average + prev_b = line[pos - unit] if pos >= unit else 0 + byte = (byte + (prev_b + prev[pos]) // 2) & 0xFF + elif filter_ == 4: # paeth + a = line[pos - unit] if pos >= unit else 0 + if y > 0: + b = prev[pos] + c = prev[pos - unit] if pos >= unit else 0 + else: + b = c = 0 + p = a + b - c + pa = abs(p - a) + pb = abs(p - b) + pc = abs(p - c) + if pa <= pb and pa <= pc: + p = a + elif pb <= pc: + p = b + else: + p = c + byte = (byte + p) & 0xFF + else: + raise ValueError("Wrong filter.") + line[pos] = byte for pixel in range(pixels_per_byte): if x + pixel < width: bmp[x + pixel, y] = ( @@ -119,7 +155,7 @@ def load( # noqa: PLR0912, PLR0915, Too many branches, Too many statements ) & pixmask src_b += 1 src += scanline + 1 - src_b = src + prev, line = line, prev return bmp, pal # RGB, RGBA or Grayscale import displayio