In my previous blog, I talked about how to use ImageMagick to square a file. Now, in this blog I’m taking it one step further.

I have a directory of photos from all over the internet, and I want to post them to a social media site. If the pictures are taller than 510 pixels, I need to square them as discussed in the last blog (and I’m adding a white padding/background). This will keep them from being cut off when I post them to the specific social media site.

Secondly, if the picture is “wide” vs “tall”, then I don’t need to add the background, but I might as well resize it to save upload/posting time. Some pictures downloaded from the internet are very large, so I’m standardizing on resizing them to a width or height of 510, whichever is smaller.

So in the Powershell, here’s what is happening:
1) Get all the files in a directory ($inputPath) and loop through them one at a time
2) Call ImageMagick “identify” to return the size of the file (primarily I need to know it’s width and height)
3) Use RegEx pattern matching to pull the width/height out of the returned string, convert them to numbers, then use compare them
4) If it is a wide picture, call the ImageMagick resize function
5) If it is a tall picture, call the ImageMagick convert function. Technically, I’m converting to a thumbnail, but it’s a very large thumbnail.

For both #4 and #5 in the above steps, the output file is a variable written to the $targetPath directory with the same filename.


$inputPath = "e:\Photos\ToResize\"
$targetPath = "e:\Photos\Resized\"
$files = get-ChildItem $inputPath  

foreach ($file in $files) 

    #$output = &  magick identify e:\Photos\ToResize\022cca60-a2a9-49b8-964e-b228acf517f3.jpg
    # shell out to run the ImageMagick "identify" command 
    $output = &  magick identify $file.FullName 
    $outFilename = $targetPath + $file.Name 

    # sample value of $output: 
    #e:\Photos\ToResize\022cca60-a2a9-49b8-964e-b228acf517f3.jpg JPEG 768x512 768x512+0+0 8-bit sRGB 111420B 0.000u 0:00.000

    write-host $output 

    $pattern = ".* (\d*?)x(\d*?) .*"
    #the first parenthese is for capturing the cityState into the $Matches array
    #the second parentheses are needed above to look for $ (which is end of line)
    #or zip code following the city/state
    $isMatch = $output -match $pattern
    if ($Matches.Count -gt 0)
        #$width = $Matches[1];
        #$height = $Matches[2];

        [int]$width = [convert]::ToInt32($Matches[1]); 
        [int]$height = [convert]::ToInt32($Matches[2]); 

        if ($height -gt $width) 
           $orientation = "tall"; 
           # shell out to run the ImageMagick "convert" command 
           & convert -define jpeg:size=510x510 $file.FullName -thumbnail "510x510>" -background white -gravity center -extent "510x510" $outFilename 
           $orientation = "wide"; 
           # shell out to run the ImageMagick "convert" command 
           & convert -resize 510x510^ $file.FullName $outFilename 
        Write-Host ("file=$($ width=$width height=$height orientation=$orientation `n`n"); 
       Write-Host ("No matches"); 

Filed under: Graphics