Anyway, after changing it to use an HBox it’s working. I’ve uploaded a new version of the CleVR Stitcher with that fix and a few others. You can install it from that box in the sidebar (unless you’re reading this via the feed).

The InterpolatedBitmapData class adds the methods getPixelBicubic and getPixelBilinear to the BitmapData class, which allows you to fetch the colour of a point that’s not on a pixel boundary. We use this when reprojecting the source images in the CleVR Stitcher, but it can work just as well for resizing an image. Bear in mind that bicubic is a lot slower than bilinear, and the quality improvement isn’t usually worthwhile. However, you’re welcome to switch to getPixelBicubic if you need to.

The basic method I’m using here for resizing is to loop through the pixels of the output image, getting the equivalent pixels in the source image. As these are found by multiplying by the ratio between the source and output sizes, the coordinates probably won’t be integers. Using regular getPixel would require rounding, and therefore give a jagged (aliased) output. The getPixelXxx methods let you pass them a Number, which needn’t be an integer, giving a much smoother result.

The sample code below shows a way of resizing an image using this method. The InterpolatedBitmapData should be created in the same way as a BitmapData, such as by draw()ing a loader onto it. The example I’ve shown below is an Event.COMPLETE handler for a Loader. Code below the cut.

var source:IBitmapDrawable = event.target.loader;
 
var original:InterpolatedBitmapData = new InterpolatedBitmapData(source.width, source.height);
original.draw(source);
 
/* The size of the output image */
var newWidth:int = 100;
var newHeight:int = 200;
 
var resized:BitmapData = new BitmapData(newWidth, newHeight);
 
var xFactor:Number = original.width / newWidth;
var yFactor:Number = original.height / newHeight;
 
/* Loop through the pixels of the output image, fetching the equivalent pixel from the input*/
for (var x:int = 0; x < newWidth; x++) {
    for (var y:int = 0; y < newHeight; y++) {
        resized.setPixel(x, y, original.getPixelBilinear(x * xFactor, y * yFactor));
    }
}

Thank you everyone who submitted bug reports. They have bee very helpful. This release should fix all of the most commonly reported problems. See below for a list of updates, and important information on installing the update.

Important: If you have previously installed the CleVR Stitcher you will need to uninstall it before upgrading. You also cannot use the self-update feature of the old Stitcher for this upgrade. This is because we have a new code signing certificate with a new company name, CleVR Ltd. To uninstall on Windows, go to Add/Remove Programs and remove CleVR Stitcher. On a Mac, go to the Applications folder and drag “CleVR Stitcher” to the Trash. You can then install as usual.

Bugs that have been fixed include:

• Large images that when resized were over 1MB were failing to load. This was by far the commonest problem reported and should work now. If anyone still has problems with images loading then do please let me know.
• Drag and drop was not working for lots of users.
• Some users on Windows reported that it was repeatedly trying to access the floppy drive.
• In a small number of cases it would freeze when the Stitch button was pressed.
• EXIF focal length data was being ignored on some Nikon images.
• The first image of a panorama was misaligned in many hand-shot images.
• In a small number of images, the rotation was being ignored when stitching.

Other enhancements include:

• Better feedback when reordering images.
• JPEG encoding is asynchronous and gives feedback rather than freezing the screen.
• Numerous improvements to the stitching algorithm.
• Several improvements to the interface.

If you haven’t tried adding hotspots to your panorama, give it a try. If you’re logged-in, you’ll find a button on the panorama page to edit them. Hotspots let you add another level of interactivity to your panoramas. You can create areas within the panorama that can be clicked to give more information or to move to another location. You can display text, images or even Flash files such as Youtube movies. Links to other locations lets you move around an area – for example, you could click on a doorway to move to a panorama inside a building or in a different room.

The library includes a number of classes that we developed as part of the CleVR Stitcher. They include a set of matrix algebra classes, ported from the Java JAMA library. These let you do standard matrix algebra stuff, and includes support for singular value decomposition and QR decomposition.

There’s also some graphics classes. One is a subclass of BitmapData that adds bicubic and bilinear interpolation. Another is a class for calculating the histogram of an image, with methods to do histogram stretching. This gives results similar to “Auto levels” in Photoshop, or “Enhance” in iPhoto.

You will find them here. They’re released under the Creative Commons attribution licence, which basically lets you do anything with them, so long as you give credit somewhere. A link to clevr.com would usually suffice. Let me know if you have any comments, patches, or if you’re using it.

This is called histogram stretching, and works by finding the lightest and darkest parts of the image and then “stretching” all of the colours so that the lightest part is white, the darkest is black, and all the others are distributed evenly between those. I’ve added a slider that allows you to set the threshold for this, which basically sets a minimum number of pixels that are required for it to count as the lightest or darkest area. You can adjust the slider to get the best results. There’s a little demo version below. Install the Stitcher below if you want to try the whole thing.

I’ve added the Histogram class to the other code that we’ve released, and bundled it all up as a library. You can get it from here: CleVR Actionscript Library. The class calculates a histogram for a bitmap image, and generates ColorMatrixFilters and ColorTransforms that can be used to correct the images.

Download it as part of the CleVR Actionscript Library

For the benefit of anyone else needing to do stuff like this, I’m releasing the library. It’s not a full port, as I only implemented the stuff that I need. It does however support most regular operations for manipulating real matrices. As well as the normal algebra stuff, it includes classes for singular value decomposition and QR decomposition. I hope others find it useful. Let me know if you’re using it. A link back to clevr.com from your site would be appreciated but is not required.

Download it as part of the CleVR Actionscript Library

The choice for the development platform will be surprising to many people. The idea of doing computer vision and image processing in Flash sounds like madness, but the advances in Flash Player 9 make it possible. While developing the CleVR panorama viewer, it became apparent to me quite how powerful some of the new features were, and the performance improvements in the new Player have made it feasible. The current version is slower than the Java stitcher, but there’s a lot more optimisation that I can do, and it’s certainly usable.

Currently it’s missing a number of features from the Java version, most importantly the ability to repair failed stitches. However, I’ve made several improvements to the algorithms, so there should be fewer failed stitches. The repair facility will be added in a future release, as will several other useful features.

Give it a try, and let me know of any bugs that you find, and any other comments that you have.