63 lines
1.7 KiB
PowerShell
63 lines
1.7 KiB
PowerShell
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param(
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[Parameter(Mandatory=$true)][string]$InputPath,
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[Parameter(Mandatory=$true)][string]$OutputPath,
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[string]$BackupPath = ""
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)
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if (!(Test-Path -LiteralPath $InputPath)) {
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throw "Input file not found: $InputPath"
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}
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if ($BackupPath -ne "") {
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Copy-Item -LiteralPath $InputPath -Destination $BackupPath -Force
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}
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Add-Type -AssemblyName System.Drawing
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# Load from a stream to avoid locking the input file (required if output overwrites input)
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$fs = [System.IO.File]::Open($InputPath, [System.IO.FileMode]::Open, [System.IO.FileAccess]::Read, [System.IO.FileShare]::ReadWrite)
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try {
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$bmp = New-Object System.Drawing.Bitmap($fs)
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} finally {
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$fs.Dispose()
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}
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$out = New-Object System.Drawing.Bitmap($bmp.Width, $bmp.Height, [System.Drawing.Imaging.PixelFormat]::Format32bppArgb)
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function IsBgPixel($c) {
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$r = [int]$c.R
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$g = [int]$c.G
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$b = [int]$c.B
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$nearGray = ([math]::Abs($r - $g) -le 10) -and ([math]::Abs($g - $b) -le 10)
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if (-not $nearGray) { return $false }
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# Typical checkerboard: very light gray and mid light gray
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$isLight = ($r -ge 235 -and $g -ge 235 -and $b -ge 235)
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$isMid = ($r -ge 205 -and $g -ge 205 -and $b -ge 205 -and $r -le 235)
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return ($isLight -or $isMid)
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}
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for ($y = 0; $y -lt $bmp.Height; $y++) {
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for ($x = 0; $x -lt $bmp.Width; $x++) {
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$c = $bmp.GetPixel($x, $y)
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if (IsBgPixel $c) {
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$out.SetPixel($x, $y, [System.Drawing.Color]::FromArgb(0, $c.R, $c.G, $c.B))
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} else {
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$out.SetPixel($x, $y, [System.Drawing.Color]::FromArgb(255, $c.R, $c.G, $c.B))
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}
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}
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}
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$tmp = "$OutputPath.tmp"
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try {
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$out.Save($tmp, [System.Drawing.Imaging.ImageFormat]::Png)
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} finally {
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$bmp.Dispose()
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$out.Dispose()
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}
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Move-Item -LiteralPath $tmp -Destination $OutputPath -Force
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