Adobe Illustrator CS6 script that rasterizes every GroupItem from the first layer of active document to the separate png file.

MegaRasterize.js

function captureImage(fileName, document, clipRect) {
    var fileOutput = new File("/tmp/exportpng/" + fileName);

    var imageCaptureOptions = new ImageCaptureOptions();
    imageCaptureOptions.resolution = 300;
    imageCaptureOptions.transparency = true;

    document.imageCapture(fileOutput, clipRect, imageCaptureOptions);
}

var docSource = app.activeDocument;

$.writeln("Document width: " + docSource.width + ", height: " + docSource.height);

var layer = docSource.activeLayer;

// Rasterize only first 3 items for debug purposes. Remove for release usage.
var groupItemsLength = layer.groupItems.length > 3 ? 3 : layer.groupItems.length;

for (var i = 0; i < groupItemsLength; i++) {
    var groupItem = layer.groupItems[i];
            
    var docTemp = app.documents.add(DocumentColorSpace.CMYK, app.activeDocument.width, app.activeDocument.height);
    var layerTemp = docTemp.layers[0];
    var groupItemTemp = groupItem.duplicate(layerTemp, ElementPlacement.PLACEATEND);
    
    var groupItemBounds = groupItemTemp.visibleBounds;
    
    var groupItemLeft = groupItemBounds[0];
    var groupItemTop = groupItemBounds[1];
    var groupItemWidth = groupItemBounds[2] - groupItemBounds[0];
    var groupItemHeight = groupItemBounds[1] - groupItemBounds[3];
    
    captureImage(i + ".png", docTemp, groupItemTemp.visibleBounds);

    $.writeln("left: " + groupItemLeft + ", top: " + groupItemTop + ", width: " + groupItemWidth + ", height: " + groupItemHeight);
    
    docTemp.close(SaveOptions.DONOTSAVECHANGES);
}