Categories
code opencv python

OpenCV Python YAML persistance

I wasn’t able to find online a complete example on how to persist OpenCV matrices in Python (so really NumPy arrays) to YAML like what cv::FileStorage will give you.
So here’s a short snippet:

import numpy as np
import yaml
# A yaml constructor is for loading from a yaml node.
# This is taken from: http://stackoverflow.com/a/15942429
def opencv_matrix_constructor(loader, node):
    mapping = loader.construct_mapping(node, deep=True)
    mat = np.array(mapping["data"])
    mat.resize(mapping["rows"], mapping["cols"])
    return mat
yaml.add_constructor(u"tag:yaml.org,2002:opencv-matrix", opencv_matrix_constructor)
# A yaml representer is for dumping structs into a yaml node.
# So for an opencv_matrix type (to be compatible with c++'s FileStorage) we save the rows, cols, type and flattened-data
def opencv_matrix_representer(dumper, mat):
    mapping = {'rows': mat.shape[0], 'cols': mat.shape[1], 'dt': 'd', 'data': mat.reshape(-1).tolist()}
    return dumper.represent_mapping(u"tag:yaml.org,2002:opencv-matrix", mapping)
yaml.add_representer(np.ndarray, opencv_matrix_representer)
#example
with open('output.yaml', 'w') as f:
    f.write("%YAML:1.0")
    yaml.dump({"a matrix": np.zeros((10,10)), "another_one": np.zeros((2,4))}, f)
#   a matrix: !!opencv-matrix
#     cols: 10
#     data: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
#       0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
#       0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
#       0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
#       0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
#       0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0,
#       0.0, 0.0, 0.0, 0.0, 0.0]
#     dt: d
#     rows: 10
#   another_one: !!opencv-matrix
#     cols: 4
#     data: [0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0, 0.0]
#     dt: d
#     rows: 2
with open('output.yaml', 'r') as f:
    print yaml.load(f)
#  {'a matrix': array([[ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
#         [ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
#         [ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
#         [ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
#         [ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
#         [ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
#         [ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
#         [ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
#         [ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.],
#         [ 0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.,  0.]]), 'another_one': array([[ 0.,  0.,  0.,  0.],
#         [ 0.,  0.,  0.,  0.]])}

There you go

Categories
code Web

Adding radial labels to Dimple.JS pie chart

Too bad Dimple.JS doesn’t have this feature built-in. They only have a boring old legend, where pie charts scream for labels that circle the actual pie (or donut).
Anyway, here’s how to get it done using some d3.js love.

Categories
code Solutions Web

Bootstrap3 fluid container with custom width sidebar

I was looking for a way to get a fluid container live side-by-side with a custom width sidebar.
A custom width sidebar can’t be achieved with a Bootstrap column, and is a total mess to get right with floats if you then need a fluid container to get a grid system for the main section.
So, here’s one solution:

JSFiddle: https://jsfiddle.net/6sfog80k/

Categories
code graphics programming video

YUYV to JPEG conversion with libjpeg

Sharing a small libjpeg snippet.
Some SO questions about it have only partial snippets:


Enjoy!
Roy

Categories
electronics

Smallest ATTiny45 USB

USB ATTiny45-20
USB ATTiny45-20


Just wanted to report on completing a quick electronics prototyping project – making a very tiny ATTiny45-based simple USB dongle.

I used the blueprints from here: http://macetech.com/blog/?q=node/46
Printed the thing on the Roland Modela in the Media Lab shop, stuffed it with components obtained from DigiKey (links) there are only 5…, and programmed with a combination of the code from macetech and this instructables tutorial, and voilla – it works.
The advantage of the ATTiny45-20 (as opposed to the 45 not ’20’, e.g. ’10’) is that it works at 5V, which is what you get from USB, and also has an internal oscillator and PLL that can go over 20MHz (@ 4.5V-5.5V), which surpasses the USB’s requirements of 16MHz. The ATTinyX5-10 will not do, as it doesn’t go over 10MHz. So basically this chip is all you need to create a USB device, how awesome is that?
This is the image I used for cutting out the board (it is to-scale at 500 DPI, meaning you can use it to mill your own board). The red marking can be used for cutting out the board:

Continue reading “Smallest ATTiny45 USB”
Categories
code graphics opencv

Quickly: How to render a PDF to an image in C++?

Using Poppler, of course!
Poppler is a very useful tool for handling PDF, so I’ve discovered lately. Having tried both muPDF and ImageMagick’s Magick++ and failed, Poppler stepped up to the challenge and paid off.
So here’s a small example of how work the API (with OpenCV, naturally):

#include <iostream>
#include <fstream>
#include <sstream>
#include <opencv2/opencv.hpp>
#include <poppler-document.h>
#include <poppler-page.h>
#include <poppler-page-renderer.h>
#include <poppler-image.h>
using namespace cv;
using namespace std;
using namespace poppler;
Mat readPDFtoCV(const string& filename,int DPI) {
    document* mypdf = document::load_from_file(filename);
    if(mypdf == NULL) {
        cerr << "couldn't read pdf\n";
        return Mat();
    }
    cout << "pdf has " << mypdf->pages() << " pages\n";
    page* mypage = mypdf->create_page(0);
    page_renderer renderer;
    renderer.set_render_hint(page_renderer::text_antialiasing);
    image myimage = renderer.render_page(mypage,DPI,DPI);
    cout << "created image of  " << myimage.width() << "x"<< myimage.height() << "\n";
    Mat cvimg;
    if(myimage.format() == image::format_rgb24) {
        Mat(myimage.height(),myimage.width(),CV_8UC3,myimage.data()).copyTo(cvimg);
    } else if(myimage.format() == image::format_argb32) {
        Mat(myimage.height(),myimage.width(),CV_8UC4,myimage.data()).copyTo(cvimg);
    } else {
        cerr << "PDF format no good\n";
        return Mat();
    }
    return cvimg;
}

All you have to do is give it the DPI (say you want to render in 100 DPI) and a filename.
Keep in mind it only renders the first page, but getting the other pages is just as easy.
That’s it, enjoy!
Roy.

Categories
Uncategorized

מאגר שמות ישראליים בעברית – Israeli hebrew names dataset

זהו פוסט ראשון בבלוג בעברית, מאחר והוא דן בנושא שמות ישראליים בעברית. לאחרונה יצא לי להתעסק בכריית שמות מדפי אינטרנט ומהר הבנתי שלא אתקדם הרבה אם לא תהיה לי רשימת מילים שהן למעשה שמות, כדי להפריד בקלות את הטקסט מהשמות.
לא מצאתי רשימה כזו פשוטה, למרות שבאתר מ.י.ל.ה של הטכניון יש לקסיקון די נרחב של מילים בעברים עם טיוג גם לשמות. למרות שאפשר בקלות לדלות משם את השמות עם JAXB על הסכמה של הXML, לא עשיתי זאת מפאת חוסר זמן וקוצר רוח.
אז עשיתי רשימה בעצמי. התחלתי ממאגר שמות שקיים אצלי ופירקתי לשם פרטי ומשפחה באמצעות רווחים, ולאחר מכן התחלתי במלאכת הכרייה שהוסיפה הרבה מאוד שמות למאגר.
לאחר מכן חזרתי למאגר שלי ומניתי את המופעים של כל שם כשם פרטי ושם משפחה, כדי לעזור בכרייה עתידית. כך אפשר למצוא עוד שמות למשל אם לוקחים את המילה שבאה לפני שם משפחה מובהק מאוד.
עם זאת ישנם שמות מאוד מבלבלים מבחינת שיוך לשם פרטי או משפחה, למשל “גל”, “שלום”, או “ברק”. לעומתם שמות מובהקים לכאן או לכאן כמו “אהוד” או “לוי”
בכל מקרה, הנה הרשימה לשימושכם החופשי.
נא לקחת בחשבון שזו רשימה חלקית ביותר, וכן המנייה של השמות חלקית ביותר גם היא.
hebrew_names
This is the first hebrew speaking post on the MTT blog, since it speaks of names in Hebrew. This is also not a translation of the above text, just a preamble to it. I’ve collected a list of Hebrew first and last names and counted the number of times a name appears as first and last on a private database of names. The result may be useful for someone extracting Hebrew names from the web.
Enjoy!
Roy.

Categories
3d Augmented Reality code graphics Mapping opengl programming Tracking video vision

Bootstrapping planar AR and tracking without markers [w/code]

Years ago I wanted to implement PTAM. I was young and naïve 🙂
Well I got a few moments to spare on a recent sleepless night, and I set out to implement the basic bootstrapping step of initializing a map with a planar object – no known markers needed, and then tracking it for augmented reality purposes.

Continue reading “Bootstrapping planar AR and tracking without markers [w/code]”
Categories
code Java programming

Apache Tapestry 5 Progress Bar with jQuery+Bootstrap [w/code]

Just sharing a code snippet about how to implement a jQuery+Bootstrap progress bar for a background operation in Tapestry 5. There’s not a lot to it, but it took me a while and serious digging through the internet to find how to make it work. Essentially it’s based on a couple of examples and references I found:

But I simplified things because I don’t like the over-design Java can easily make you do…

Continue reading “Apache Tapestry 5 Progress Bar with jQuery+Bootstrap [w/code]”