512px Image Previews/Thumbnails from 10GB+ PSB Files

@Chris Sw 

I have created a couple of scripts for you, I think the second one may be a bit faster than the first, but you will need to test it on your large files and report back.

I'm hoping that these will be faster than using Batch Actions, Image Processor or Image Processor Pro etc.

At the moment you are asked to select one or more files. This could be easily changed to select a top-level/root folder and then process all files of a given file type at this root level. Another option would be to process all files in all nested subfolders.

A new directory "512px" will be created on the desktop for the thumbnails.

The first script resizes to fit 512px on the longest edge, maintaining the original aspect ratio. The second script creates a 512px 1:1 square aspect ratio. Either of these could be changed.

Script version 1.0A:

/*
Create 512px Thumbs.jsx
v1.0A 26th December 2023, Stephen Marsh
https://community.adobe.com/t5/photoshop-ecosystem-discussions/512px-image-previews-thumbnails-from-10gb-psb-files/td-p/14313667
*/

var selectFile = File.openDialog("Select the file/s:", Multiselect = true);

var saveFolder = new Folder("~/Desktop/512px")
if (!saveFolder.exists) {
    saveFolder.create();
}

var timeDiff = {
    setStartTime: function() {
        d = new Date();
        time = d.getTime();
    },
    getDiff: function() {
        d = new Date();
        t = d.getTime() - time;
        time = d.getTime();
        return t;
    }
};

timeDiff.setStartTime();

var counter = 0;

for (var i = 0; i < selectFile.length; i++) {

    openAsSmartObject(false, true, new File(selectFile[i]), true);

    activeDocument.flatten();
    activeDocument.convertProfile("sRGB IEC61966-2.1", Intent.RELATIVECOLORIMETRIC, true, false);
    activeDocument.bitsPerChannel = BitsPerChannelType.EIGHT;

    if (activeDocument.height > activeDocument.width) {
        activeDocument.resizeImage(null, UnitValue(512, "px"), null, ResampleMethod.BILINEAR);
    } else {
        activeDocument.resizeImage(UnitValue(512, "px"), null, null, ResampleMethod.BILINEAR);
    }

    saveJPEG(new File(saveFolder + "/" + activeDocument.name.replace(/\-\d+$/, '')), true, true);

    activeDocument.close(SaveOptions.DONOTSAVECHANGES);

    counter++;

}

alert("512px Thumbnail Generation Completed!" + "\r" + "Files selected: " + selectFile.length + "\r" + "Files processed: " + counter + "\r" + "(" + timeDiff.getDiff() / 1000 + " seconds)");
saveFolder.execute();


///// FUNCTIONS /////

function openAsSmartObject(dontRecord, forceNotify, null2, smartObject) {
    function s2t(s) {
        return app.stringIDToTypeID(s);
    }
    var descriptor = new ActionDescriptor();
    descriptor.putBoolean(s2t("dontRecord"), dontRecord);
    descriptor.putBoolean(s2t("forceNotify"), forceNotify);
    descriptor.putPath(s2t("null"), null2);
    descriptor.putBoolean(s2t("smartObject"), smartObject);
    executeAction(s2t("open"), descriptor, DialogModes.NO);
}

function saveJPEG(saveLocation, copy, lowerCase) {
	function s2t(s) {
        return app.stringIDToTypeID(s);
    }
	var descriptor = new ActionDescriptor();
	var descriptor2 = new ActionDescriptor();
	descriptor2.putInteger( s2t( "extendedQuality" ), 6 ); // Compression value
	descriptor2.putEnumerated( s2t( "matteColor" ), s2t( "matteColor" ), s2t( "none" ));
	descriptor.putObject( s2t( "as" ), s2t( "JPEG" ), descriptor2 );
	descriptor.putPath( s2t( "in" ), saveLocation );
	descriptor.putBoolean( s2t( "copy" ), copy );
	descriptor.putBoolean( s2t( "lowerCase" ), lowerCase );
	executeAction( s2t( "save" ), descriptor, DialogModes.NO );
}

Script version 1.0B:

/*
Create 512px Thumbs.jsx
v1.0B 26th December 2023, Stephen Marsh
https://community.adobe.com/t5/photoshop-ecosystem-discussions/512px-image-previews-thumbnails-from-10gb-psb-files/td-p/14313667
*/

var selectFile = File.openDialog("Select the file/s:", Multiselect = true);

var saveFolder = new Folder("~/Desktop/512px")
if (!saveFolder.exists) {
    saveFolder.create();
}

var timeDiff = {
    setStartTime: function() {
        d = new Date();
        time = d.getTime();
    },
    getDiff: function() {
        d = new Date();
        t = d.getTime() - time;
        time = d.getTime();
        return t;
    }
};

timeDiff.setStartTime();

var counter = 0;

for (var i = 0; i < selectFile.length; i++) {

    app.documents.add(512, 512, 72, "_Temp", NewDocumentMode.RGB);
    placeFile(new File(selectFile[i]), false, 0, 0);
    var docName = activeDocument.activeLayer.name.replace(/\.[^\.]+$/, '');
    activeDocument.convertProfile("sRGB IEC61966-2.1", Intent.RELATIVECOLORIMETRIC, true, false);
    saveJPEG(new File(saveFolder + "/" + docName + ".jpg"), true, true);
    activeDocument.close(SaveOptions.DONOTSAVECHANGES);
    counter++;

}

alert("512px Thumbnail Generation Completed!" + "\r" + "Files selected: " + selectFile.length + "\r" + "Files processed: " + counter + "\r" + "(" + timeDiff.getDiff() / 1000 + " seconds)");
saveFolder.execute();


///// FUNCTIONS /////

function placeFile(null2, linked, horizontal, vertical) {
    var s2t = function (s) {
        return app.stringIDToTypeID(s);
    };
    var AD = new ActionDescriptor();
    AD.putInteger(s2t("ID"), 1);
    AD.putPath(s2t("null"), null2);
    AD.putBoolean(s2t("linked"), linked); // false for embedded
    AD.putEnumerated(s2t("freeTransformCenterState"), s2t("quadCenterState"), s2t("QCSAverage"));
    AD.putUnitDouble(s2t("horizontal"), s2t("pixelsUnit"), horizontal);
    AD.putUnitDouble(s2t("vertical"), s2t("pixelsUnit"), vertical);
    AD.putObject(s2t("offset"), s2t("offset"), AD);
    executeAction(s2t("placeEvent"), AD, DialogModes.NO);
}

function saveJPEG(saveLocation, copy, lowerCase) {
	function s2t(s) {
        return app.stringIDToTypeID(s);
    }
	var descriptor = new ActionDescriptor();
	var descriptor2 = new ActionDescriptor();
	descriptor2.putInteger( s2t( "extendedQuality" ), 6 ); // Compression value
	descriptor2.putEnumerated( s2t( "matteColor" ), s2t( "matteColor" ), s2t( "none" ));
	descriptor.putObject( s2t( "as" ), s2t( "JPEG" ), descriptor2 );
	descriptor.putPath( s2t( "in" ), saveLocation );
	descriptor.putBoolean( s2t( "copy" ), copy );
	descriptor.putBoolean( s2t( "lowerCase" ), lowerCase );
	executeAction( s2t( "save" ), descriptor, DialogModes.NO );
}

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

This test script extracts the thumbnail from test.psb and writes it to test.jpg. Check on your large files.

var file = new File("F:\\((\\test.psb");
var jpg  = new File("F:\\((\\test.jpg");

main(file, jpg);

function main(file, jpg)
    {
    try { 
        file.open("r");
        file.encoding = "BINARY";

        var offset = 0;

        var hrd_len = 26;

        var buff = file.read(hrd_len);
        offset += hrd_len;

        var color_mode_len = get_integer(file.read(4));

        offset += 4 + color_mode_len;

        file.seek(offset, 0);

        var image_resource_len = get_integer(file.read(4));
        offset += 4 + image_resource_len;

        var buff = file.read(image_resource_len);

        file.close();

        var x = buff.indexOf("8BIM\x04\x0C\x00\x00");

        if (x < 0) { alert("Thumbnail not found"); return; }

        var len = get_integer(buff.substr(x+8, 4));

        buff = buff.substr(x+12);
        
        var format = get_integer(buff.substr(0, 4));
        var w      = get_integer(buff.substr(4, 4));
        var h      = get_integer(buff.substr(8, 4));

        buff = buff.substr(28, len-28);

        jpg.open("w");
        jpg.encoding = "BINARY";
        jpg.write(buff);
        jpg.close();    

        alert("Thumbnail " + w + "x" + h);
        }
    catch (e) { alert(e); throw(e); } 
    }

function get_integer(s)
    {
    try { 
        var len = s.length;            

        var mult = 1;
        var ret = 0;                 

        for (var i = len-1; i >=0; i--)
            {
            ret += s.charCodeAt(i) * mult;                 
            mult *= 256;
            }

        return ret;
        }
    catch (e) { alert(e); throw(e); } 
    }

I recently had to generate hundreds of thumbnails, fitting each proportionally within a square of specific pixel dimensions, for a similar task but not for FileMaker. After playing around with several tools, the one that ended up working the best was GraphicConverter (shareware), using its File > Drag and Drop Converter command although it has other conversion/batch options. I only had to define a Batch Function preset and output folder, threw the images into the drop zone, and it was done in seconds by using all CPU cores.

However, the files I thumbnailed were not as large as the ones you have mentioned. And I don’t know if it handles PSB. However, GraphicConverter is scriptable.

(I tried several Adobe tools first, but for various reasons including the specific file formats I had to thumbnail, no Adobe tool could actually do it properly.)

You have obviously tried a lot of things.

If the native thumb isn't the right size, then there isn't much that you can do for *extraction* as the size is what it is.

The best thing you can do is use automation such as Image Processor or Image Processor Pro to open such large files and then save smaller copies.

As you know, this will not take milliseconds, even with a script.

Perhaps somebody else has a creative idea... If the Bridge preview files could be accessed that may be your best bet.

EDIT: If you look at your Bridge cache prefs, you will see a path to the folder, then there are subfolders for 256px or 1024px and then further subfolders that contain the preview images –

/Users/username/Library/Caches/Adobe/Bridge/Cache/v36/1024/DesktopEAFAFFC3/my template.psd.png etc. Some files are PNG and others JPEG, I don't know why the format isn't consistent.