Informaticus

As a computer scientist I never keep backups of my emails because Google takes care of them :) Recently, I read news about mass-email losses at gmail so I thought it would be a good idea to spend some gigabytes of my backup drives for my valuable emails. The tool of my choice was getmail and luckily I found a lot of postings where users reported that they had successfully retrieved all their mails. Like always when you try something yourself, it doesn't work out. I got an error that the selected mailbox wasn't found on the server. After installing Thunderbird and accessing the GMail account (via IMAP) I found out, that in my case the mailbox name is [Gmail]/Alle Nachrichten instead of [Gmail]/All Mail. I tend do switch languages on webpages with logins so I was surprised because I had spanish as selected language. Maybe these directories are created only once? I'll never know but if you run into the same problem, try to access the GMail account via IMAP and note the directory name for "All Mail / Alle Nachrichten".

Code snippet that fails on my account:

[...]
mailboxes = ("[Gmail]/All Mail",)
[...]

This is my actual config file (located in ~/.getmail/)

[retriever]
type = SimpleIMAPSSLRetriever
server = imap.gmail.com
username = YOUR_EMAIL_ADDRESS(at)gmail.com
password = YOUR_PASSWORD
mailboxes = ("[Gmail]/Alle Nachrichten",)
port = 993

[destination]
type = Mboxrd
path = /Volumes/elements/backup/gmail/gmail-backup.mbox
#type = Maildir
#path = /Volumes/elements/backup/gmail/maildir/


[options]
verbose = 2
message_log = /Volumes/elements/backup/gmail/gmail.log
received = false
delivered_to = false
read_all = false

... or else you won't be able to save your file. Even if you chose a different filename! A possible workaround is to create a new file and copy & paste your content.

Today I fixed a memory bug in one of my programs. Albeit I always release memory cvReleaseImage after allocating it with cvCreateImage, memory consumption was enormous. Commenting out some of the source code quickly showed the responsible code fragments. Using cvCreateImage and afterwards cvCloneImage made it impossible to release the initially allocated memory. Therefore after some iterations (depending on your main memory) this program will crash. To fix this issue simply replace the cvCloneImage with cvCopy.

Bad code:

DO
 img2 = cvCreateImage(cvSize(img->width, img->height), img->depth, img->nChannels);
[...]
 img = cvCloneImage(img2);
 cvReleaseImage(&img2);
LOOP

Good code:

DO
 img2 = cvCreateImage(cvSize(img->width, img->height), img->depth, img->nChannels);
[...]
 //img = cvCloneImage(img2);
 cvCopy(img2,img,NULL);
 cvReleaseImage(&img2);
LOOP

I want to share my collection of links of how to build a classifier based on haar-like feature using OpenCV. If you know another (open source) implementation please leave me a message!

An example where a bowl is detected
http://lab.cntl.kyutech.ac.jp/~kobalab/nishida/opencv/OpenCV_ObjectDetection_HowTo.pdf

A wiki describing how to build a haar classifier for robotic vision
http://cgi.cse.unsw.edu.au/~cs4411/wiki/index.php?title=OpenCV_Guide#Haar_Classifier

Frequently asked questions about haar training (mainly basics about positive and negative input file format, how to read the output of the OpenCV haar training program ...)
http://www.computer-vision-software.com/blog/2009/11/faq-opencv-haartraining/

Short summary of the output during haar training
http://cv-kolaric.blogspot.com/2008/03/output-from-haartrainingexe.html

How to fix cvboost.cpp if you encounter a "bad flag" error during haar training
http://tech.groups.yahoo.com/group/OpenCV/message/69620

Another example of how to detect a bowl
http://www.computer-vision-software.com/blog/2009/06/opencv-haartraining-detect-objects-using-haar-like-features/

One of the best tutorial (imho) of how to build a cascade of boosted classifiers based on haar-like features. It's a step by step manual for face detection.
http://note.sonots.com/SciSoftware/haartraining.html