All posts by willtalmadge

Making things faster, color and free fast fourier transforms

I have been quietly working on moving the image processing for Birch Note onto the iPhone GPU. The benefit of this is faster performance, and color! Currently, because of performance considerations I have to convert the image to greyscale before doing the flattening. Color would require triple the processing and triple the time on a CPU. Which I felt was simply too long. While GPUs don’t give you this for free, they are designed to process 4 channels (RGBA) simultaneously, so they are quite efficient at it.

This has required me to develop some capabilities on my own that I could not find elsewhere for a price I could afford. Namely, I need a good mixed-radix fast Fourier transform that runs on the iPhone 5 GPU for some of the filtering I do. I have completed this and decided to do something a little crazy. I’ve posted the source code to github. If you’d like to check it out go here . It is built on top of a rudimentary image processing monad and it is written in C++. It’s a bit verbose, but it has proved useful in handling the OpenGL plumbing of a complicated rendering pipeline automatically.

This is early stage code so you might find it difficult to use or understand. Please contact me if you want to use it. Your questions will help me determine what is most valuable to write up as documentation.

Birch Note, a computer vision note capture app, needs testers

If you take a lot of handwritten notes and you have patience for untested software, I need your help. I’ve been developing an iPhone app for capturing handwritten notes and uploading them to the cloud in my spare time. It uses computer vision techniques to automatically produce high quality results without any intervention from the user.  I started developing this for my own use; but, I now believe that I’ve brought this technology to a point where a few patient early adopters might find this useful. I would like to put this app in the app store. But first, I need a few patient, brave souls to help me test my software and get it ready for a broader audience. If you think you might be interested please read more about Birch Note then become a tester.


Coming soon: Birch Note alpha test

If you take a lot of handwritten notes, I need your help. I’ve been developing an iPhone app for capturing handwritten notes for my own use. I now believe that more people would find this useful. I need a few brave souls to help me test my software. If you think you might be interested please read on to understand the what and the why of Birch Note.

What is Birch Note?


Birch note makes permanently saving your hand written notes quick and simple while on the go. It requires no special hardware other than a smartphone, pen or pencil and a notebook with a special border printed on the page (see figure). It uses computer vision wizardry to process your notes by automatically correcting page curl, non-uniform lighting and contrast adjustment. They are then automatically uploaded to the cloud for backup or later reading.

Where do my notes go?

Currently notes can be automatically uploaded to Evernote. You can also email your notes or save them to your photos. If you are interested in support for other cloud note storage services such as Simplenote, Springpad, Fetchnotes or some other service please let me know.

What devices do you support?

Currently the iPhone 5, 5s or 5c are the only supported devices. I would like to support as many mobile devices and platforms as possible in the near future, including tablets. I would love to hear which devices and platforms people are most interested in.

Why Birch Note?

I created Birch Note for my own use. I have tried all of the digital note taking devices out there. I’ve tried tablets, styluses, and smart pens. I found that I would always come back to my old friend, pen and paper. But, I still had a need to store and organize my hand written notes better. I decided to embrace pen and paper.  I could take pictures of my notes with my smartphone but I wasn’t happy with the results. The pages would be warped and couldn’t be cropped. Correcting the image often required fiddling with knobs and levers in various cam scanner apps for my iPhone. I wanted something that generated results I could be happy with, reliably, quickly and accurately.

With Birch Note all of my notes are backed up as I take them, there is no longer a need to fear losing a notebook. I can have all my notes with me at all times without a need to carry several notebooks. If I go for a walk I can carry a small pocket notebook and still have all my notes from my letter size notebook in my phone.

What’s the deal with the name?

The Celtic people held an ancient belief in the magical properties of the bark of the birch tree. They believed that the bark harvested from a birch tree hit by lightning would forever protect and preserve anything written on it. I thought it was fitting. Now you can make birch notes that will forever protect and preserve your writing, sans the lightning and actual birch trees.

How do I get it?

I will be announcing details on how to become an alpha tester for Birch Note. If you are very eager to try this out even if it means using early stage software then I would like you as a tester. I will provide a link to where a coil bound notebook can be purchased that is compatible with Birch Note. The app is not currently in the app store and it won’t be until it reaches the beta phase. Each alpha tester’s device will have to be individually enabled in this early phase.