<# | |
.SYNOPSIS | |
Resize an image | |
.DESCRIPTION | |
Resize an image based on a new given height or width or a single dimension and a maintain ratio flag. | |
The execution of this CmdLet creates a new file named "OriginalName_resized" and maintains the original | |
file extension | |
.PARAMETER Width | |
The new width of the image. Can be given alone with the MaintainRatio flag | |
.PARAMETER Height | |
The new height of the image. Can be given alone with the MaintainRatio flag | |
.PARAMETER ImagePath | |
The path to the image being resized | |
.PARAMETER MaintainRatio | |
Maintain the ratio of the image by setting either width or height. Setting both width and height and also this parameter | |
results in an error | |
.PARAMETER Percentage | |
Resize the image *to* the size given in this parameter. It's imperative to know that this does not resize by the percentage but to the percentage of | |
the image. | |
.PARAMETER SmoothingMode | |
Sets the smoothing mode. Default is HighQuality. | |
.PARAMETER InterpolationMode | |
Sets the interpolation mode. Default is HighQualityBicubic. | |
.PARAMETER PixelOffsetMode | |
Sets the pixel offset mode. Default is HighQuality. | |
.EXAMPLE | |
Resize-Image -Height 45 -Width 45 -ImagePath "Path/to/image.jpg" | |
.EXAMPLE | |
Resize-Image -Height 45 -MaintainRatio -ImagePath "Path/to/image.jpg" | |
.EXAMPLE | |
#Resize to 50% of the given image | |
Resize-Image -Percentage 50 -ImagePath "Path/to/image.jpg" | |
.NOTES | |
Written By: | |
Christopher Walker | |
#> | |
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() | |
} | |
} | |
} |
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Thanks for this function! I'm including it in an upcoming TechSnips.io video I'm doing. You may want to include Good work on this. Feel free to join us if you'd like. ;) https://www.techsnips.io/join-us |
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I tried this on a bunch of JPEGs at 50%, but whilst the pixel sizes were halved, the file sizes all went up! Think there is a quality setting you need to expose somewhere. |
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@piers7, You must save the file as a jpeg, the default value is png. ie use
|
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Probably worth to add
to release original files. |
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@Kirill Yea that's a great idea! Thanks. Updated the gist. |
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I used your function as a starting place for a project I was working on (I really like it, thanks!) One addition I added was the ability of grabbing the "Date Taken" attribute from a photograph. The code for grabbing that property was something like this:
|
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how to preserve the image's transparent background ? |
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Great function, thx! As @adbertram wrote, adding |
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Fixed an issue with the percentage variable.