Scripting / Web Development

PowerShell Image Resize Function

by Lewis · Sun 18th January, 2015

One for the toolbox. Some bits were done by someone else but I can’t remember who, I just parameterised the input, quality, size and output for easy use.

Read on…

$Date = Get-Date -Format "yyyy-MM-dd-HHmmss"
$Screenshot = "myImage.jpg"
$OutputFolder = "C:\ResizedScreenshot"

ResizeImage $Screenshot 90 1280 ($OutputFolder+"\images\"+$Date+".jpg")

$Date = Get-Date -Format "yyyy-MM-dd-HHmmss"

$Screenshot = "myImage.jpg"

$OutputFolder = "C:\ResizedScreenshot"

ResizeImage $Screenshot 90 1280 ($OutputFolder+"\images\"+$Date+".jpg")

Use as above. No commas between parameters!

Function ResizeImage() {
    param([String]$ImagePath, [Int]$Quality = 90, [Int]$targetSize, [String]$OutputLocation)

    Add-Type -AssemblyName "System.Drawing"

    $img = [System.Drawing.Image]::FromFile($ImagePath)

    $CanvasWidth = $targetSize
    $CanvasHeight = $targetSize

    #Encoder parameter for image quality
    $ImageEncoder = [System.Drawing.Imaging.Encoder]::Quality
    $encoderParams = New-Object System.Drawing.Imaging.EncoderParameters(1)
    $encoderParams.Param[0] = New-Object System.Drawing.Imaging.EncoderParameter($ImageEncoder, $Quality)

    # get codec
    $Codec = [System.Drawing.Imaging.ImageCodecInfo]::GetImageEncoders() | Where {$_.MimeType -eq 'image/jpeg'}

    #compute the final ratio to use
    $ratioX = $CanvasWidth / $img.Width;
    $ratioY = $CanvasHeight / $img.Height;

    $ratio = $ratioY
    if ($ratioX -le $ratioY) {
        $ratio = $ratioX
    }

    $newWidth = [int] ($img.Width * $ratio)
    $newHeight = [int] ($img.Height * $ratio)

    $bmpResized = New-Object System.Drawing.Bitmap($newWidth, $newHeight)
    $graph = [System.Drawing.Graphics]::FromImage($bmpResized)
    $graph.InterpolationMode = [System.Drawing.Drawing2D.InterpolationMode]::HighQualityBicubic

    $graph.Clear([System.Drawing.Color]::White)
    $graph.DrawImage($img, 0, 0, $newWidth, $newHeight)

    #save to file
    $bmpResized.Save($OutputLocation, $Codec, $($encoderParams))
    $bmpResized.Dispose()
    $img.Dispose()
}

Function ResizeImage() {

param([String]$ImagePath, [Int]$Quality = 90, [Int]$targetSize, [String]$OutputLocation)

Add-Type -AssemblyName "System.Drawing"

$img = [System.Drawing.Image]::FromFile($ImagePath)

$CanvasWidth = $targetSize

$CanvasHeight = $targetSize

#Encoder parameter for image quality

$ImageEncoder = [System.Drawing.Imaging.Encoder]::Quality

$encoderParams = New-Object System.Drawing.Imaging.EncoderParameters(1)

$encoderParams.Param[0] = New-Object System.Drawing.Imaging.EncoderParameter($ImageEncoder, $Quality)

# get codec

$Codec = [System.Drawing.Imaging.ImageCodecInfo]::GetImageEncoders() | Where {$_.MimeType -eq 'image/jpeg'}

#compute the final ratio to use

$ratioX = $CanvasWidth / $img.Width;

$ratioY = $CanvasHeight / $img.Height;

$ratio = $ratioY

if ($ratioX -le $ratioY) {

$ratio = $ratioX

}

$newWidth = [int] ($img.Width * $ratio)

$newHeight = [int] ($img.Height * $ratio)

$bmpResized = New-Object System.Drawing.Bitmap($newWidth, $newHeight)

$graph = [System.Drawing.Graphics]::FromImage($bmpResized)

$graph.InterpolationMode = [System.Drawing.Drawing2D.InterpolationMode]::HighQualityBicubic

$graph.Clear([System.Drawing.Color]::White)

$graph.DrawImage($img, 0, 0, $newWidth, $newHeight)

#save to file

$bmpResized.Save($OutputLocation, $Codec, $($encoderParams))

$bmpResized.Dispose()

$img.Dispose()

}

Tags: images powershell

Mark says:

Sat 12th September, 2015 at 17:08

This is just what I am looking for but I’m not having any luck with it! I am getting “Exception calling “Save” with “3” argument(s): “A generic error occurred in GDI+.”

Any ideas? I am running Windows 7. Do I need to call/load any objects/cmdlets for this to run? Thanks!
Lewis says:

Sat 12th September, 2015 at 17:18

Hi Mark, not that I’m aware of. The Add-Type call within the function handles the requirements. Perhaps with it being Windows 7 just check you have the latest PowerShell version and the latest .NET framework installed too. I probably writer this on Windows 8.1 so I assume that will have had .NET 4.5. Let me know if you’re still struggling after updating those and rebooting and I’ll spin up a Windows 7 machine to test.

Sorry Mark, I found this in Spam of all places – Akismet being a little over zealous!
Lewis says:

Tue 15th September, 2015 at 14:27

Hi Mark, sorry for the late reply. I attempted to use the WordPress app on my phone but for some reason, the reply didn’t send – apologies! If you’re running on Windows 7, ensure you have the latest and greatest .NET 4.5.2 installed alongside the latest and greatest version of PowerShell. Version 4 should be OK as I’m pretty sure that’s what I developed it on. If you’re still struggling, let me know and I’ll see what I can do to help but please bear with me as I’m currently working internationally.