Combining multiple images into a single image using a script

While on the general/related topic of stacking multiple source docs to a single doc (not creating a horizontal or vertical layout):

https://community.adobe.com/t5/photoshop-ecosystem-discussions/script-to-open-files-and-layer-them/m-p/12532657#U14933502

https://community.adobe.com/t5/photoshop-ecosystem-discussions/script-to-automate-load-files-into-stack/m-p/13499068#U14928257

Edit: Just saw Stephen's reply appear after I posted this. His script looks superior if you don't have the files already imported as layers. The one below might still be useful if you want to stack all the existing layers in an existing document.

I used AI whip up this script, it seems to work based on my testing.

It works with layers even if they're all different sizes. It will set the canvas width to the widest image.

It also has true/false options at the top for how to align layers if they aren't all the same width, specifically whether to center them or left-align them, and whether to align to the nearest pixel if centering them.

The script assumes the layers are already all loaded into the same document and in the order you want to stack them. So you can keep using "Load files into stack" if you have a lot of them.

#target photoshop

/*
    Script: Stack Layers Vertically
    Description: Stacks layers vertically with options for alignment (Left vs Center).
*/

// ================= CONFIGURATION ================= //

var ALIGN_CENTER = true;   // Set to true to center layers horizontally, false to align left
var SNAP_TO_PIXEL = true;  // When centering, whether to align the position to the nearest whole pixel. Only applies if ALIGN_CENTER is true. 

// ================================================= //

function main() {
    if (app.documents.length === 0) {
        alert("Please open a document with layers first.");
        return;
    }

    var doc = app.activeDocument;
    
    // Save original ruler units to restore later
    var originalUnits = app.preferences.rulerUnits;
    app.preferences.rulerUnits = Units.PIXELS;

    var layers = doc.layers;
    var totalHeight = 0;
    var maxWidth = 0;
    var visibleLayers = [];

    // 1. Gather Data and Calculate Canvas Size
    for (var i = 0; i < layers.length; i++) {
        var layer = layers[i];
        
        // We only care about visible layers (ignores backgrounds/hidden drafts)
        if (layer.visible) {
            visibleLayers.push(layer);
            
            var bounds = layer.bounds; // [left, top, right, bottom]
            var w = bounds[2].value - bounds[0].value;
            var h = bounds[3].value - bounds[1].value;
            
            totalHeight += h;
            if (w > maxWidth) {
                maxWidth = w;
            }
        }
    }

    // 2. Resize the canvas
    // We resize to the calculated total height and max width found.
    // Anchor is TOPCENTER if centering, TOPLEFT if not.
    var anchor = ALIGN_CENTER ? AnchorPosition.TOPCENTER : AnchorPosition.TOPLEFT;
    doc.resizeCanvas(maxWidth, totalHeight, anchor);

    // 3. Move layers into position
    var currentY = 0;

    for (var i = 0; i < visibleLayers.length; i++) {
        var layer = visibleLayers[i];
        
        var bounds = layer.bounds;
        var currentLeft = bounds[0].value;
        var currentTop = bounds[1].value;
        var layerWidth = bounds[2].value - bounds[0].value;
        var layerHeight = bounds[3].value - bounds[1].value;

        // Calculate Target X
        var targetX = 0;

        if (ALIGN_CENTER) {
            // (Canvas Width - Layer Width) / 2
            targetX = (maxWidth - layerWidth) / 2;
        } else {
            // Left align means X is always 0
            targetX = 0;
        }

        // Snap to nearest pixel if requested
        if (ALIGN_CENTER && SNAP_TO_PIXEL) {
            targetX = Math.round(targetX);
        }

        // Calculate Delta (How much to move)
        var deltaX = targetX - currentLeft;
        var deltaY = currentY - currentTop;
        
        layer.translate(deltaX, deltaY);

        // Advance Y cursor
        currentY += layerHeight;
    }

    // Restore original units
    app.preferences.rulerUnits = originalUnits;
}

// Run the function wrapped in suspendHistory for a single Undo step
app.activeDocument.suspendHistory("Stack Layers Vertically", "main()");

I have written scripts for such tasks. Let me dig up the link...

You could write a script for this. Read the height of each image, create a new canvas the total size, and then place each image at the correct offset. Or look for an image tiling script, I bet something is available online.

You can use Contact Sheet without gaps, but you do need to determine what the end size should be.

MyraFerguson_0-1765391833042.png

In this example, I made 3 rectangles that were 6 x 4 inches @ 72 ppi, so

• In the Document section, I made the width 6 inches and the height 12 inches, and used 72 ppi
• In the Thumbnails section, I placed it down first with 1 column and 3 rows without auto spacing and the vertical and horizontal space set to 0