CleVR » Panoramic photography and image stitching blog » Apollo

Photo stitcher update, plus short links

matt — Wed, 22 Jul 2009 18:24:57 +0000

First I must apologise for the lack of updates. All I can say is that I’ve been very busy. With that in mind, I am happy to announce two updates. First, and most important, is a new version of the CleVR Stitcher. I know that a lot of people have been having problem with poor stitching of some images. I’ve been having the same problems. Anyhow, I’m happy to say that this update greatly improves stitch quality. This is mainly down to improvements in focal length estimation and initial image warping. It’s amazing the difference that makes. I’ve also tweaked some thresholds and values to improve stitching in other ways. Let me know if it works for you.

In other matters, we now have short links implemented, using the domain clvr.eu. Just look for the link on the panorama page. For example, see http://clvr.eu/9ny for an Apollo 11 panorama. These links are perfect for sharing your panoramas on Twitter. Once again, let me know what you think.

Major update to CleVR Stitcher

matt — Wed, 05 Sep 2007 14:06:02 +0000

I’ve just pushed out an update to the CleVR Stitcher which is probably the biggest improvement yet. Loads more features, loads of bugs fixed and a much nicer interface. You will find all the details here: CleVR panoramic photo Stitcher. As always, it’s totally free. Let me know what you think.

I decided to enter it into the Adobe AIR Developer Derby. It’s hard to judge its chances, but I’d love to win that squishy stress ball. If they’re going on innovation, I’d say they’d be hard-pressed to find an AIR app that is pushing the boundaries more than this. In terms of using AIR technologies, we’re using almost all of them! We’ll wait and see…

Image enhancement with histogram stretching in Actionscript

matt — Fri, 27 Jul 2007 14:28:59 +0000

Yesterday’s update to the CleVR Stitcher has a number of new features. One of these is image enhancement for the finished panorama. This corrects under- or over-exposed images, and works in a similar way to “Auto levels” in Photoshop, or Enhance in iPhoto. See below for more details and a demo.

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.

Bicubic and bilinear interpolation in Actionscript 3

matt — Mon, 02 Jul 2007 09:53:55 +0000

For the second release of utility code from CleVR Stitcher, the Adobe AIR panoramic photo stitcher, I’m offering our InterpolatedBitmapData class.
The class adds support for bicubic and bilinear interpolation to the Actionscript BitmapData class. It adds two public methods – getPixelBilinear and getPixelBicubic. You can call these with sub-pixel coordinates and it will interpolate the RGB value for that point. This should be useful for anyone doing more complex transformations than those offered by the Matrix class. I hope it will be useful to someone. Do let me know if you’re using it. As ever, a link back to clevr.com is appreciated but not required.

Download it as part of the CleVR Actionscript Library

Linear algebra and matrix manipulation library for Actionscript 3

matt — Sat, 30 Jun 2007 11:56:05 +0000

While developing the CleVR Stitcher, I needed to do quite a bit of linear algebra. I was disappointed to find that there was no Actionscript library out there for doing this, so I had to write my own. Rather than doing it from scratch, I decided to start with NIST’s Java Matrix library: JAMA, which is in the public domain.

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

Adobe AIR panoramic photo stitcher

matt — Mon, 25 Jun 2007 14:01:22 +0000

Update: The CleVR Stitcher can now be found at http://www.clevr.com/stitcher

The Stitcher is the oldest part of CleVR, originally developed nearly four years ago, so it’s needing an upgrade. It was developed in Java, delivered by Web Start, a system that I’ve never been happy with. I decided that the best plan for the new version was to rewrite it from scratch. It’s a Flex-based Adobe AIR app. AIR, formerly called Apollo, is a new cross-platform runtime under development by Adobe. The first beta was released earlier this month, and it’s a joy to develop for. I’m pleased to announce the first alpha version of the new AIR-based CleVR Stitcher. You’ll need a CleVR account to use it. It’s free, and only takes a couple of minutes to sign up.

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.

Web apps on the desktop

matt — Fri, 03 Nov 2006 12:52:23 +0000

While CleVR is mostly web-based, the Stitcher has always needed to be a desktop app. This is for a number of reasons. Primarily it’s because it needs access to the local filesystem so that you can import your photos. Also, it is processor intensive, so runs best as a native app.

However, it also needs to be tightly-integrated with the server, so that it can handle the uploading, authentication and similar. It also needs to be cross-platform, as we don;t have the resources to develop separate apps for Mac, Windows (and possibly Linux). The current system is pretty good – we use Java Webstart which allows us to launch from the browser, while giving us the access we need to the filesystem and native libraries. However, I’ve never been totally happy with it, and am always looking for a better solution. Luckily, there seem to be some on the way.

The other day, I ran across Adobe Apollo, which looks pretty damn cool. This is still in development, but will allow Flash, Javascript and HTML apps to be deployed on the desktop. That sounds a lot like CleVR to me. From first appearances, it seems to be a much more elegant system than Webstart (and the Java platform in general). The HTML renderer is based on WebKit, which of course makes it even cooler.

This stuff seems to be becoming all the rage at the moment – Pulse Laser has a few more examples. WebKit on Rails looks fun, though we don’t use Ruby here so it’s not massively relevant to us.