mask-rescaler.ps1

# Mask Rescaler
# =============
#
# If the PDF image extractor has given you masks that don't match the image dimensions, this script can help.
#
# First, make sure to remove ALL files from the directory that aren't the mismatched images/masks. Also remove
# any unwanted images; the images must be in the 'image, mask, image, mask, ...' order that the extractor
# requires. Place this script in the same directory as the images/masks. Run the script.
#
# Rescaled masks have `_resized` appended to their name, and all old masks are moved to a new directory
# surprisingly called `old_masks`. Images are unaffected.
#
# If you still don't understand what this script does, I recommend not using it.
#
#
# Spappz 2024
#
# MIT License

Add-Type -Assembly System.Drawing

# Resize-Image function by Christopher Walker at https://gist.github.com/someshinyobject/617bf00556bc43af87cd
# Copied 2022-01-20
Function Resize-Image {
	[CmdLetBinding(
		SupportsShouldProcess = $true, 
		PositionalBinding = $false,
		ConfirmImpact = 'Medium',
		DefaultParameterSetName = 'Absolute'
	)]
	Param (
		[Parameter(Mandatory = $True)]
		[ValidateScript({
				$_ | ForEach-Object {
					Test-Path $_
				}
			})][String[]]$ImagePath,
		[Parameter(Mandatory = $False)][Switch]$MaintainRatio,
		[Parameter(Mandatory = $False, ParameterSetName = 'Absolute')][Int]$Height,
		[Parameter(Mandatory = $False, ParameterSetName = 'Absolute')][Int]$Width,
		[Parameter(Mandatory = $False, ParameterSetName = 'Percent')][Double]$Percentage,
		[Parameter(Mandatory = $False)][System.Drawing.Drawing2D.SmoothingMode]$SmoothingMode = 'HighQuality',
		[Parameter(Mandatory = $False)][System.Drawing.Drawing2D.InterpolationMode]$InterpolationMode = 'HighQualityBicubic',
		[Parameter(Mandatory = $False)][System.Drawing.Drawing2D.PixelOffsetMode]$PixelOffsetMode = 'HighQuality',
		[Parameter(Mandatory = $False)][String]$NameModifier = 'resized'
	)
	Begin {
		If ($Width -and $Height -and $MaintainRatio) {
			Throw 'Absolute Width and Height cannot be given with the MaintainRatio parameter.'
		}

		If (($Width -xor $Height) -and (-not $MaintainRatio)) {
			Throw 'MaintainRatio must be set with incomplete size parameters (Missing height or width without MaintainRatio)'
		}

		If ($Percentage -and $MaintainRatio) {
			Write-Warning 'The MaintainRatio flag while using the Percentage parameter does nothing'
		}
	}
	Process {
		ForEach ($Image in $ImagePath) {
			$Path = (Resolve-Path $Image).Path
			$Dot = $Path.LastIndexOf('.')

			#Add name modifier (OriginalName_{$NameModifier}.jpg)
			$OutputPath = $Path.Substring(0, $Dot) + '_' + $NameModifier + $Path.Substring($Dot, $Path.Length - $Dot)
				
			$OldImage = New-Object -TypeName System.Drawing.Bitmap -ArgumentList $Path
			# Grab these for use in calculations below. 
			$OldHeight = $OldImage.Height
			$OldWidth = $OldImage.Width

			If ($MaintainRatio) {
				$OldHeight = $OldImage.Height
				$OldWidth = $OldImage.Width
				If ($Height) {
					$Width = $OldWidth / $OldHeight * $Height
				}
				If ($Width) {
					$Height = $OldHeight / $OldWidth * $Width
				}
			}

			If ($Percentage) {
				$Product = ($Percentage / 100)
				$Height = $OldHeight * $Product
				$Width = $OldWidth * $Product
			}

			$Bitmap = New-Object -TypeName System.Drawing.Bitmap -ArgumentList $Width, $Height
			$NewImage = [System.Drawing.Graphics]::FromImage($Bitmap)
				
			#Retrieving the best quality possible
			$NewImage.SmoothingMode = $SmoothingMode
			$NewImage.InterpolationMode = $InterpolationMode
			$NewImage.PixelOffsetMode = $PixelOffsetMode
			$NewImage.DrawImage($OldImage, $(New-Object -TypeName System.Drawing.Rectangle -ArgumentList 0, 0, $Width, $Height))

			If ($PSCmdlet.ShouldProcess("Resized image based on $Path", "save to $OutputPath")) {
				$Bitmap.Save($OutputPath)
			}
				
			$Bitmap.Dispose()
			$NewImage.Dispose()
			$OldImage.Dispose()
		}
	}
}

# Grab paths to all the files in the directory
$imageList = Get-ChildItem |
	Where-Object { $_.Name -match '\.png$' } |
	Select-Object -ExpandProperty Name |
	Resolve-Path |
	Select-Object -ExpandProperty Path

# Assume the order is image, mask, image, mask
$resizedMasks = [System.Collections.Generic.List[string]]::new()
for ($i = 0; $i -lt $imageList.Count; $i = $i + 2) {
	# Read files
	$image = New-Object -TypeName System.Drawing.Bitmap -ArgumentList $imageList[$i]
	$mask = New-Object -TypeName System.Drawing.Bitmap -ArgumentList $imageList[$i + 1]
	# Rescale and save mask based on the image's dimensions
	if ($image.Width -ne $mask.Width -or $image.Height -ne $mask.Height) {
		$resizedMasks.Add($imageList[$i + 1])
		Resize-Image -Width $image.Width -Height $image.Height -ImagePath $imageList[$i + 1]
	}
	# Release resources
	$image.Dispose()
	$NewImage.Dispose()
}

# Move old masks into an `old_masks` directory as clean-up
if (-not (Test-Path ../old-masks)) {
	$null = New-Item -ItemType Directory -Name ../old_masks
}
$resizedMasks | ForEach-Object { Move-Item -Path $_ -Destination ../old_masks }