Browsing by Author "Stoliński, Sebastian"

Now showing 1 - 5 of 5

Access status: Open Access ,
Analiza wymagań dla systemu elektronicznego oceniania rozwiązań zadań egzaminacyjnych
(Wydawnictwa AGH, 2009) Bieniecki, Wojciech; Stańdo, Jacek; Stoliński, Sebastian
In his paper the idea of e-evaluation is presented. This is a system for checking sheets of paper in the examination by the examiner directly on the computer screen. The advantage of such a solution is, as experience has shown, to improve the quality of the preparation of the test and its evaluation. The process of automation of the examination includes systems of electronic tests, commonly implemented both as a standalone or distributed application. We present the project architecture of a web system for scanning exam sheets, distributing the scans to examiners and managing the whole process of examination in a secure and effective way. A long-term goal is to let Central Examination Board deploy the system in maturity and high school examinations.
Access status: Open Access ,
Automatic detection and evaluation of the spline function plot
(Wydawnictwa AGH, 2010) Stoliński, Sebastian; Bieniecki, Wojciech; Stańdo, Jacek
In this paper the image processing algorithm for automatic recognition and evaluation of drawn-by-hand function plot is presented, which enables processing of the scanned examination sheets. The student is to draw the plot in a printed coordinate system. Because the plot is drawn manually, the teacher checks if the drawn curve crosses some characteristic »lattice« points. In a case of complex plot (few curves or lines - spline function) the curve may be discontinuous and the student should mark the endings of the segments. The computer program compares the model plot to the query plot and as the result it returns the degree of compliance between the plots. The algorithm works in the following steps: extraction of the coordinate system area from the sheet (for query and model solutions), extraction of the plot segments from the coordinate system (for query and model solutions), comparison of the extracted plots with respect of some tolerance. The algorithm has been successfully tested upon a group of 50 sheets. Some errors oceurred for solutions with strike-throughs, amendments, lines drawn by mistake. Big amount of unrecognized plots has impact on the relative errors.
Access status: Open Access ,
Eksperymentalne porównanie filtrów medianowych do usuwania szumów impulsowych z obrazów barwnych
(Wydawnictwa AGH, 2005) Stoliński, Sebastian; Grabowski, Szymon
The median filter is a classic tool for impulse noise attenuation. Unfortunately, there is no natural ordering in vector spaces and thus the median definition for, e.g., pixels in RGR color space requires a change. The first generalization of the median filter into vector spaces was VMF filter (1990). In the following years, many alternatives have been proposed, offering often better image restoration quality. In this work we extensively compare known filtering algorithms, taking into account both their image restoration accuracy and filtering speed. Additionally, we analyze the effectiveness of several filters on so-called microimages, i.e., small excerpts from real images. Also, we introduce the concept of using the directional metric as a decision criterion in several existing filters.
Access status: Open Access ,
On efficient implementations of median filters in theory and in practice
(Wydawnictwa AGH, 2009) Stoliński, Sebastian; Grabowski, Szymon; Bieniecki, Wojciech
The median filter, in its scalar and vector form, is a classic tool for suppressing impulse noise from images. In this paper we present a theoretical algorithm for worst-case optimized scalar median finding and an efficient implementation of the vector median filter (VMF). The former has not better complexity than two existing algorithms, but matches them for some relation between L and r, and is obtained using means which are novel in this context. The latter achievement is a simple practical idea which, for large enough masks, speeds up the standard (naive) implementation of VMF several times. We also presented results of a multi-threaded implementation, run on multicore machines.
Access status: Open Access ,
The algorithms for automatic evaluation of selected examination tasks from the geometry
(Wydawnictwa AGH, 2011) Stoliński, Sebastian; Bieniecki, Wojciech
W artykule zaprezentowano algorytm pozwalający na automatyczne rozpoznawanie i ocenianie narysowanych ręcznie wykresów, przetwarzający zeskanowane arkusze egzaminacyjne. Zadaniem ucznia jest wykreślenie obiektu złożonego z kilku podstawowych kształtów, takich jak krzywe, wielokąty, linie, na podstawie równań, na wydrukowanym arkuszu zawierającym układ współrzędnych. Wykres jest rysowany odręcznie, więc ocenianie powinno zakładać pewną tolerancję i być zgodne ze sposobem oceniania przez nauczyciela. Algorytm powinien ignorować nadmiarowe obiekty (skreślenia, dopiski, mylnie wykreślone linie). Zaprezentowany algorytm porównuje obrazy wzorcowe z ocenianym rozwiązaniem i zwraca wartość będącą miarą podobieństwa wykresów. Algorytm działa w trzech etapach: ekstrakcja obrazu układu współrzędnych dla obrazu wzorcowego i ocenianego, wyodrębnienie linii zawierających rozwiązanie z reszty obrazu, porównanie wyodrębnionych obiektów dla obrazu wzorcowego i ocenianego z uwzględnieniem założonej tolerancji. Algorytm zweryfikowano na próbie 50 arkuszy egzaminacyjnych.