$result = '';

for ($i = 0; $i < strlen($data); $i++) {

$result .= chr(ord($data[$i]) ^ 0xAA);

}

return $result;

$p = $a + $b - $c;

$pa = abs($p - $a);

$pb = abs($p - $b);

$pc = abs($p - $c);

if ($pa <= $pb && $pa <= $pc) return $a;

elseif ($pb <= $pc) return $b;

else return $c;

$recon = '';

$len = strlen($line);

for ($i = 0; $i < $len; $i++) {

$curr = ord($line[$i]);

if ($filter == 0) {

$recon .= chr($curr);

} elseif ($filter == 1) {

$left = ($i >= $bpp) ? ord($recon[$i - $bpp]) : 0;

$recon .= chr(($curr + $left) % 256);

} elseif ($filter == 2) {

$above = ($prev_line != '') ? ord($prev_line[$i]) : 0;

$recon .= chr(($curr + $above) % 256);

} elseif ($filter == 3) {

$left = ($i >= $bpp) ? ord($recon[$i - $bpp]) : 0;

$above = ($prev_line != '') ? ord($prev_line[$i]) : 0;

$recon .= chr(($curr + floor(($left + $above) / 2)) % 256);

} elseif ($filter == 4) {

$left = ($i >= $bpp) ? ord($recon[$i - $bpp]) : 0;

$above = ($prev_line != '') ? ord($prev_line[$i]) : 0;

$up_left = ($i >= $bpp && $prev_line != '') ? ord($prev_line[$i - $bpp]) : 0;

$recon .= chr(($curr + paeth_predictor($left, $above, $up_left)) % 256);

}

}

return $recon;

$file = fopen($file_path, 'rb');

if (!$file) return false;

$signature = fread($file, 8);

if ($signature != "\x89PNG\r\n\x1A\n") {

fclose($file);

return false;

}

$idat_data = '';

while (!feof($file)) {

$chunk_length_data = fread($file, 4);

if (strlen($chunk_length_data) < 4) break;

$chunk_length = unpack('N', $chunk_length_data)[1];

$chunk_type = fread($file, 4);

if ($chunk_length == 0) {

$chunk_data = '';

} else {

$chunk_data = fread($file, $chunk_length);

}

$chunk_crc = fread($file, 4);

if ($chunk_type == 'IHDR') {

$ihdr_data = unpack('Nwidth/Nheight/Cbit_depth/Ccolor_type/Ccompression/Cfilter/Cinterlace', substr($chunk_data, 0, 13));

$width = $ihdr_data['width'];

$height = $ihdr_data['height'];

$bit_depth = $ihdr_data['bit_depth'];

$color_type = $ihdr_data['color_type'];

if ($color_type != 6 || $bit_depth != 8) { // Assuming RGBA, 8-bit

fclose($file);

return false;

}

} elseif ($chunk_type == 'IDAT') {

$idat_data .= $chunk_data;

} elseif ($chunk_type == 'IEND') {

break;

}

}

fclose($file);

$compressed_data = $idat_data;

$decompressed = @gzuncompress($compressed_data);

if ($decompressed === false) return false;

$bytes = [];

$filter_byte_length = $width * 4 + 1; // RGBA + filter byte per line

$scanline_length = $width * 4; // RGBA bytes per line

$prev_recon = str_repeat(chr(0), $scanline_length);

for ($y = 0; $y < $height; $y++) {

$line_start = $y * $filter_byte_length;

$filter = ord($decompressed[$line_start]);

$filtered_line = substr($decompressed, $line_start + 1, $scanline_length);

$recon_line = reconstruct_line($filtered_line, $filter, $prev_recon, 4);

for ($x = 0; $x < $scanline_length; $x += 4) {

$r = ord($recon_line[$x]);

$g = ord($recon_line[$x + 1]);

$b = ord($recon_line[$x + 2]);

$a = ord($recon_line[$x + 3]);

$bytes[] = $r;

$bytes[] = $g;

$bytes[] = $b;

$bytes[] = $a;

}

$prev_recon = $recon_line;

}

// Trim padding bytes if necessary

while (!empty($bytes) && $bytes[count($bytes) - 1] == 0) {

array_pop($bytes);

}

echo "Extracted bytes count: " . count($bytes) . "<br>"; // Debug

return $bytes;