Script to find colour in "black & white" jpgs

@leol30 

EDIT: Script updated to version 1.1 where files that fail the test for neutrality are moved to a "Rejected" folder.

This Photoshop script will process the root/top-level of an input folder for supported files and will log files to the desktop in a text file that have a Standard Deviation value for the sum of the a+b channels that is greater than 0.00 (0.00 being fully neutral).

if (theValue > 0.00) {

If this does prove useful I am happy to make changes to the script.

P.S. I am more comfortable scripting Photoshop than Bridge, which is why this is a Photoshop script, despite this topic being on in the Bridge forum.

Here is the full script for Photoshop:

/*
Batch Log Non-Neutral B&W Files from Input Folder.jsx
https://community.adobe.com/t5/bridge-discussions/script-to-find-colour-in-quot-black-amp-white-quot-jpgs/td-p/14141472
v1.1 - 11th October 2023, Stephen Marsh

Info:
This Photoshop script will process the root/top-level of an input folder
for supported files and will log files to the desktop in a text file
that have a Standard Deviation value for the sum of the a+b channels
that is greater than 0.00 (0.00 being fully neutral). A new folder
named "Rejected" will be created in the input folder and documents
which fail will be moved to this folder.
*/

#target photoshop

if (app.documents.length === 0) {

    // Select the folder containing the files
    var inputFolder = Folder.selectDialog("Select the input folder", "");

    // Add or remove supported file extensions as required
    var inputFiles = inputFolder.getFiles(/\.(jpg|jpeg|tif|tiff|psd|psb|png|bmp|webp|tga)$/i);
    inputFiles.sort();

    // Set the input file counter
    var inputFileCounter = 0;

    // Set the failed file counter
    var failedCounter = 0;

    // Initial log file entries
    var dateTime = new Date().toLocaleString();
    var logFile = new File("~/Desktop/Neutral File Evaluation.log");
    if (logFile.exists)
        logFile.remove();
    var os = $.os.toLowerCase().indexOf("mac") >= 0 ? "mac" : "windows";
    if (os === "mac") {
        var logFileLF = "Unix";
    } else {
        logFileLF = "Windows";
    }
    logFile.open("w");
    logFile.encoding = "UTF-8";
    logFile.lineFeed = logFileLF;
    logFile.writeln(dateTime);
    logFile.writeln(inputFolder.fsName + "/" + "Rejects" + "/");
    logFile.close();

    // Process the files
    for (var i = 0; i < inputFiles.length; i++) {
        open(inputFiles[i]);
        
        // Convert to Lab mode
        activeDocument.changeMode(ChangeMode.LAB);
        
        // Histogram evaluation
        var aCha = theHistProps(activeDocument.channels[1].histogram);
        var bCha = theHistProps(activeDocument.channels[2].histogram);
        // theMean = [0] | theMedian = [1] | theStandDev = [2]
        var theValue = (((aCha[2] + bCha[2]) / 2).toFixed(2));
        
        /* Change neutral target value as required */
        if (theValue > 0.00) {

            // Rejected files variables and folder
            var theDoc = activeDocument;
            var theName = theDoc.name;
            var theFolder = Folder(theDoc.path + "/" + "Rejects");
            if (!theFolder.exists) {
                theFolder.create()
            }

            try {
                writeFailedLogEntry();
                failedCounter++;
                
                // Copy the rejected files
                File(theDoc.fullName).copy(theFolder + "/" + theName);
                
                // Remove the original files
                theDoc.fullName.remove();

            } catch (e) {}
            // Close without saving
            activeDocument.close(SaveOptions.DONOTSAVECHANGES);
        } else {
            // Close without saving
            activeDocument.close(SaveOptions.DONOTSAVECHANGES);
        }
        inputFileCounter++;
    }

    // End of script notification
    alert(inputFileCounter + " files processed:" + "\r" + failedCounter + " files failed");

} else {
    alert('No documents should be open when running this script!');
}


///// FUNCTIONS /////

function writeFailedLogEntry() {
    var os = $.os.toLowerCase().indexOf("mac") >= 0 ? "mac" : "windows";
    if (os === "mac") {
        var logFileLF = "Unix";
    } else {
        logFileLF = "Windows";
    }
    logFile.open("a");
    logFile.encoding = "UTF-8";
    logFile.lineFeed = logFileLF;
    logFile.writeln("FAILED = (" + theValue + ") " + activeDocument.name + "\r");
    logFile.close();
}

function theHistProps(theHist) {
    /* Based on https://community.adobe.com/t5/photoshop/how-to-get-the-histogram-s-std-dev/td-p/9875041 */
    // get total number;
    var thePixels = 0;
    for (var m = 0; m < theHist.length; m++) {
        thePixels = thePixels + theHist[m];
    }
    // get mean and median
    var theMean = 0;
    var aTotal = 0;
    var check = false;
    for (var n = 0; n < theHist.length; n++) {
        theMean = theMean + (n * theHist[n] / thePixels);
        aTotal = aTotal + theHist[n];
        if (aTotal >= thePixels / 2 && check === false) {
            theMedian = n;
            check = true;
        }
    }
    // get standard deviation
    var theStandDev = 0;
    for (var o = 0; o < theHist.length; o++) {
        theStandDev = theStandDev + (Math.pow((o - theMean), 2) * theHist[o]);
    }
    theStandDev = Math.sqrt(theStandDev / thePixels);
    // Return the properties: theMean = [0] | theMedian = [1] | theStandDev = [2]
    return ([theMean, theMedian, theStandDev]);
}

1. Copy the code text to the clipboard
2. Open a new blank file in a plain-text editor (not in a word processor)
3. Paste the code in
4. Save as a plain text format file – .txt
5. Rename the saved file extension from .txt to .jsx
6. Install or browse to the .jsx file to run (see below)

https://prepression.blogspot.com/2017/11/downloading-and-installing-adobe-scripts.html