How to create a picture library using powershell in sharepoint 2013 server?

function Create-SharePointLibrary { 
    [CmdletBinding()]    
    Param(    
       [Parameter(Mandatory=$true, Position=0, ValueFromPipeline=$true)]    
       [string]$webUrl,
       [Parameter(Mandatory=$true, Position=1)]   
       [string]$LibraryName, 
       [Parameter(Mandatory=$true, Position=2)]
       [string]$Description, 
       [Parameter(Mandatory=$false, Position=3)]
       [string]$LibraryTemplate
    )  
   Process   
   {  
      Start-SPAssignment -Global    
      $spWeb = Get-SPWeb -Identity $webUrl       
      $spListCollection = $spWeb.Lists    
      $spLibrary = $spListCollection.TryGetList($LibraryName)  
      if($spLibrary -ne $null) {
          Write-Host -f Yellow "Library $LibraryName already exists in the site"

      } else {           
          Write-Host -NoNewLine -f yellow "Creating  Library - $LibraryName"   
          $spListCollection.Add($LibraryName, $Description, $LibraryTemplate)    
          $spLibrary = $spWeb.GetList($spWeb.ServerRelativeUrl+"/"+"$LibraryName") 
          Write-Host -f Green "...Success!"    
      }            
      Stop-SPAssignment -Global  
   } 
} 

Calling Function

$webUrl = "http://sever:port"
#-----------Picture Library------------
$PicLibName = "Pictures"  
$LibraryTemplateDL = [Microsoft.SharePoint.SPListTemplateType]::PictureLibrary
Create-SharePointLibrary $webUrl  $PicLibName $PicLibName $LibraryTemplateDL

Try it as below:

Add-PSSnapin "Microsoft.SharePoint.PowerShell"
Start-SPAssignment -Global
$SPWeb = Get-SPWeb -Identity "http://test"
$listTemplate = $SPWeb.ListTemplates["Picture Library"]
$SPWeb.Lists.Add("Custom Picture Library","Custom Picture Library desc",$listTemplate)
$list = $SPWeb.Lists["Custom Picture Library"]
$list.Title = "Custom Picture Library"
$list.Update()
$SPWeb.Dispose()    
Stop-SPAssignment -Global