631 research outputs found
Image enhancement with MatLab algorithms
No full textNowadays, a lot of applications use digital images. For example in face recognition to detect and tag persons in photograph, for security control, and a lot of applications that can be found in smart cities, as speed control in roads or highways and cameras in traffic lights to detect drivers ignoring red light. Also in medicine digital images are used, such as x-ray, scanners, etc. These applications depend on the quality of the image obtained. A good camera is expensive, and the image obtained depends also on external factor as light.
To make these applications work properly, image enhancement is as important as, for example, a good face detection algorithm. Image enhancement also can be used in normal photograph, for pictures done in bad light conditions, or just to improve the contrast of an image. There are some applications for smartphones that allow users apply filters or change the bright, colour or contrast on the pictures.
This project compares four different techniques to use in image enhancement. After applying one of these techniques to an image, it will use better the whole available dynamic range. Some of the algorithms are designed for grey scale images and others for colour images. It is used Matlab software to develop and present the final results. These algorithms are Successive Means Quantization Transform (SMQT), Histogram Equalization, using Matlab function and own implemented function, and V transform.
Finally, as conclusions, we can prove that Histogram equalization algorithm is the simplest of all, it has a wide variability of grey levels and it is not suitable for colour images. V transform algorithm is a good option for colour images. The algorithm is linear and requires low computational power. SMQT algorithm is non-linear, insensitive to gain and bias and it can extract structure of the data.
RESUMEN.
Hoy en día incontable número de aplicaciones usan imágenes digitales. Por ejemplo, para el control de la seguridad se usa el reconocimiento de rostros para detectar y etiquetar personas en fotografías o vídeos, para distintos usos de las ciudades inteligentes, como control de velocidad en carreteras o autopistas, cámaras en los semáforos para detectar a conductores haciendo caso omiso de un semáforo en rojo, etc. También en la medicina se utilizan imágenes digitales, como por ejemplo, rayos X, escáneres, etc. Todas estas aplicaciones dependen de la calidad de la imagen obtenida. Una buena cámara es cara, y la imagen obtenida depende también de factores externos como la luz.
Para hacer que estas aplicaciones funciones correctamente, el tratamiento de imagen es tan importante como, por ejemplo, un buen algoritmo de detección de rostros. La mejora de la imagen también se puede utilizar en la fotografía no profesional o de consumo, para las fotos realizadas en malas condiciones de luz, o simplemente para mejorar el contraste de una imagen. Existen aplicaciones para teléfonos móviles que permiten a los usuarios aplicar filtros y cambiar el brillo, el color o el contraste en las imágenes.
Este proyecto compara cuatro técnicas diferentes para utilizar el tratamiento de imagen. Se utiliza la herramienta de software matemático Matlab para desarrollar y presentar los resultados finales. Estos algoritmos son Successive Means Quantization Transform (SMQT), Ecualización del histograma, usando la propia función de Matlab y una nueva función que se desarrolla en este proyecto y, por último, una función de transformada V.
Finalmente, como conclusión, podemos comprobar que el algoritmo de Ecualización del histograma es el más simple de todos, tiene una amplia variabilidad de niveles de gris y no es adecuado para imágenes en color. El algoritmo de transformada V es una buena opción para imágenes en color, es lineal y requiere baja potencia de cálculo. El algoritmo SMQT no es lineal, insensible a la ganancia y polarización y, gracias a él, se puede extraer la estructura de los datos
FFT i ett historiskt perspektiv [Elektronisk resurs]
No full textNågra nedslag i Fouriertransformens historia och FFT:ns ursprung från 1805 och framåt behandlas i denna populära betraktelse. Vi stannar upp ett slag hos Gauss, funderar över vad han gjort för oss ingenjörer och vi avslutar med en del praktiska konsekvenser och tips som är aktuella idag.</p
FFT i ett historiskt perspektiv
No full textNågra nedslag i Fouriertransformens historia och FFT:ns ursprung från 1805 och framåt behandlas i denna populära betraktelse. Vi stannar upp ett slag hos Gauss, funderar över vad han gjort för oss ingenjörer och vi avslutar med en del praktiska konsekvenser och tips som är aktuella idag
Active Noise Control in Propeller Aircraft
No full textA noisy environment dominated by low frequency noise can often be improved
through the use of active noise control. This situation arises naturally in
propeller aircraft where the propellers induce periodic low frequency noise
inside the cabin. The cabin noise is typically rather high, and the passenger
flight comfort could be improved considerably if this level were significantly
reduced. This paper addresses same design aspects for multiple-reference active
noise control systems based on the feedforward strategy. The paper also
discusses the operation of narrowband feedforward active noise control system
and presents results from experiments
A Method for Reduced Finite Precision Effects in Parallel Filtering Echo Cancellation
No full textThe two-path algorithm is an adaptive filter algorithm based on a parallel filter structure, which has been found to be useful for line echo cancellation as well as for acoustic echo cancellation. It is well known that in finite precision arithmetic, the adaptation process of adaptive algorithms can be reduced or even halted due to finite precision effects. This paper proposes a variant of the two-path scheme where the effects of quantization are reduced, without any significant increase in complexity. The improvement is shown by simulations using bandlimited flat spectrum noise as well as real speech signals
Tro i vardagen : En studie av en undervisningsmodells effekter gällande elevers förståelse och engagemang i religionskunskap
No full textStudy: Degree project in teacher education, Advanced level, 15 hp University of Skövde Title: Religious belief in everyday life – a study of the effects of a teaching model focusing on religious belief in everyday life Number of pages:42 Author: Johanna Claesson Tutor: Kennert Orlenius Date: Jan 2009 Keywords: Religious study, students´ understanding, students´ commitment, Buddhism This paper presents the execution and the result of a project examining how a tutorial model (called the model of everyday religious practice) focusing on how Buddhism is expressed in the daily life of Buddhists believers, affects students understanding of and commitment in religious studies. In the project, Thai students have partaken by producing sex posters and a picture-show with the help of their own photographs and short texts. However, the picture-show was mainly produced by the author of this paper. These posters and the picture-show were brought to Sweden to figure as teaching material during a lesson in religious studies for students in year eight in a Swedish school. The Swedish students participated in focus-discussions about religion as well as religious studies before and after this lesson in order to make it possible to analyse the lesson´s affects, regarding understanding and commitment, on the students. In the result of this paper, this tutorial model appears, on one hand, to encourage students to commitment in religious studies by adding an emotive dimension to the lesson which helps the students to an authentic experience. On the other hand, it is not unequivocal whether the students did gain understanding or not for religious studies. The lesson enabled the students to see that they are likely to experience some usefulness of religious studies in their lives outside school and thereby the students gained some understanding for the subject. However, it is not clear whether this understanding is complete or not. It is likely that the teacher in planning the lessons also need to take two other tutorial models, presented in this paper, in consideration. Finally, this paper ends with a discussion about which impact the result of this study might have on how religious studies are thought in Swedish schools
Adaptive Active Control of Machine-Tool Vibration In a Lathe [Elektronisk resurs]
No full textIn the turning operation the relative dynamic motion between cutting tool and workpiece, or vibration, is a frequent problem, which affects the result of the machining, and in particular, the surface finish. Tool life is also influenced by vibration. Noise in the working environment frequently occurs as a result of dynamic motion between the cutting tool and the workpiece. With proper machine design, i.e. improved stiffness of the machine structure, the problem of relative dynamic motion between cutting tool and workpiece may be partially solved. However, by active control of machine-tool vibration, a further reduction of the dynamic motion between cutting tool and workpiece can be achieved. It was found that adaptive feedback control of tool vibration in the cutting speed direction, based on the filtered-x LMS-algorithm, enables a reduction in vibration, by up to 40 dB at 1.5 kHz, and by approximately 40 dB at 3 kHz. It was also observed that the introduction of leakage in the filtered-x LMS-algorithm improved the stability properties of the feedback control system. A significant improvement in the workpiece surface was observed and a substantial improvement in the acoustic noise level was obtained with adaptive control.</p
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