This powershell script uses ImageMagick to find gaps between documents arranged vertically in a scanned image and crops out those images into individual files. Changed to fix BermanID output (no dash after B[0-9][A-Z]).

FindDocsInScanAndSeparate.ps1

# A PowerShell script to use ImageMagick to find documents
# arranged vertically in scanned images
# and crop out each into separate images.
#
# Usage: ./findGapsBetweenScans.ps1 [-extension abc] [-threshold float ][-nosource] [-nodelete]
#
# Will analyze all images with extention abc (default is bmp)
# in current folder.
#
# if -nodeltee switch is used then script will skip deleting of temp files
#         useful when testing as rowDev function can take a while, especially
#         in folder with many large source images.
# if -nosource switch is used then script will skip analyzing source images
#         and just work from any .txt files in temp folder. Use after a -nodelete.
#         Using -nosource switch will automatically activate -nodelete.
# if -threshold is provided this changes what standard deviations of the pixes in a line
#         is considered uniform enough to be considered as a gap.

# **** Note this version tries to extract BermanIDs from the names.

param (
    [string]$extension = "bmp",
    [float]$threshold = 0.1,
    [switch]$nodelete = $false,
    [switch]$nosource = $false,
    [switch]$help = $false
)

if ($help) {
    Write-Host Will analyze all images with extention abc (default is bmp)
    Write-Host in current folder.
    Write-Host 
    Write-Host if -nodeltee switch is used then script will skip deleting of temp files
    Write-Host \t useful when testing as rowDev function can take a while, especially
    Write-Host \t in folder with many large source images.
    Write-Host if -nosource switch is used then script will skip analyzing source images
    Write-Host \t and just work from any .txt files in temp folder. Use after a -nodelete.
    Write-Host \t Using -nosource switch will automatically activate -nodelete.
    Write-Host if -threshold is provided this changes what standard deviations of the pixes in a line
    Write-Host \t is considered uniform enough to be considered as a gap.
    $host.exit
}

# Always need an output folder:
New-Item -ItemType directory -Path $PSScriptRoot/output -Force

if ($nosource) {
    $nodelete = $true
    Write-Host nosource switch set, skipping $extension files and using temp .txt files.
    Write-Host Skipping temp folder creation, because with nosource it must already exist.
    Write-Host "If you get errors that temp\XYZ.txt cannot be found then temp .txt files do not exist"
    Write-Host and you need to run the script without the -nosource flag to create them.
}
else {
    Write-Host "Finding documents in scans in current folder with extension $extension."
    Write-Host "Creating temp folder."
    New-Item -ItemType directory -Path $PSScriptRoot/temp -Force
}
if ($nodelete) {
    Write-Host nodelete switch is true. Will not delete temp .txt files after use.
}
function cropper {
    $fileName = $gapInfo[0]
    Write-Host The arraylist has $gapInfo.Count values.
    # The arraylist has one entry for the filename, and two for each gap, there is always 1 more
    # gap than there are cards. So starting with arraylist.Count (e.g. 9) take 1 off for the name (8)
    # and 2 off for the extra gap info (6), divide by two to get number of cards. 
    $numCards = ($gapInfo.Count - 3) / 2
    Write-Host That means the scan should have $numCards cards
    for ($i = 0; $i -lt (2 * $numCards); $i = $i + 2) {
        $overGapEnd = $gapInfo[($i + 2)] - 10
        $overGapStart = $overGapEnd - $gapInfo[($i + 1)] + 10
        $underGapEnd = $gapInfo[($i + 4)] - 10
        $height = $underGapEnd - $overGapStart
        #Write-Host crop from y $overGapStart to $underGapEnd for a height of $height
        $bmpName = "$fileName.$extension"
        $cropParams = "x$height+0+$overGapStart"
        $position = $i / 2 + 1
        if ($fileName -match ("(B.{1,3})\-([0-9][0-9][0-9])\-([0-9][0-9][0-9])\-([0-9][0-9][0-9])\-(.*)")) {
            $keepPos = $position + 1
            $replace = "`$1`$$keepPos-`$5"
            $fileName = $fileName -replace ("(B.{1,3})\-([0-9][0-9][0-9])\-([0-9][0-9][0-9])\-([0-9][0-9][0-9])\-(.*)"), ($replace)
        }
        $output = "$PSScriptRoot/output/$fileName.jpg"
        # Uncomment next line to see during process what it's sending to IM.
        #Write-Host magick.exe $bmpName "-crop" $cropParams $output
        & magick.exe $bmpName "-crop" $cropParams $output
        if (!$nodelete) {
            Remove-Item $PSScriptRoot\temp\$fileName.txt
        }
    }
}
function rowDev {
    Get-ChildItem $PSScriptRoot -Filter *.$extension | 
        Foreach-Object {
        $fName = $_.BaseName
        Write-Host Getting line by line standard deviations for $_
        & magick $_ -resize 10% -crop x1 +repage -format "%[fx:standard_deviation]\n" info: >$PSScriptRoot/temp/$fName.txt
    }
}

function findGaps {
    [int]$j = 0
    [bool]$lowDev = 0
    [bool]$gapEndend = 0
    [bool]$inCard = 
    [int]$gapCount = 0
    [System.Collections.ArrayList]$gapInfo = @()
    Get-ChildItem $PSScriptRoot"\temp" -Filter *.txt |
        Foreach-Object {
        $j = 0
        [int]$lineCounter = 0
        $gapCount = 0
        $gapInfo = @()
        $gapInfo += $_.BaseName
        $lines = [System.IO.File]::ReadLines( "$PSScriptRoot\temp\$_" )
        foreach ( $line in $lines) {
            [float]$stDev = $line
            if ( $stDev -lt $threshold ) {
                #Write-Host $_.BaseName line $lineCounter $stDev lessthan 0.015
                $j++
            }
            elseif ($j -gt 9) {
                $gapCount++
                [int]$gapLength = (10 * $j)
                $gapEndLine = (10 * $lineCounter)
                #Write-Host In $_.BaseName the $gapCount"st/nd" gap, lasting $gapLength lines, ended at about $gapEndLine
                $gapInfo += ($gapLength, $gapEndLine)
                $j = 0
            }
            else {
                $lowDev = 0
                $inCard = 1
                $j = 0
            }
            $gapEndend = 0
            $lineCounter++
        }
        # last line is not recorded as a gap end because it probably does not have a high standard deviation
        # So we have to add the last line of the scan as a gap end.
        # We will assume it's a gap end and has a gapLength of at least 1.
        $gapEndend = 1
        $gapEndLine = (10 * $lineCounter)
        $gapLength = (10 * $j)
        $gapInfo += ($gapLength, $gapEndLine)
        # Next 4 lines have useful debug info, uncomment if needed.
        # Write-Host **********************************************************************************************
        # for ($i = 0; $i -lt $gapInfo.Count; $i++) {
        #     Write-Host gapInfo index $i is $gapInfo[$i]
        # }
        cropper($gapInfo)
    }
}
    

if (!$nosource) {
    rowDev
}
findGaps

if (!$nodelete) {
    Remove-Item -path $PSScriptRoot\temp -recurse
}