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1.
Braz. arch. biol. technol ; 64: e21200217, 2021. tab, graf
Article in English | LILACS | ID: biblio-1339310

ABSTRACT

Abstract The proficiency of image processing is of extreme importance in perceiving and collecting information from the images, which includes the process of changing or interpreting existing images. In medical image processing, imaging with more accuracy plays a crucial role in better diagnosis or for the posterior analysis of treatment. Magnetic Resonance Imaging (MRI) is a medicinal creative tool for studying the internal structures and functionalities of human brain, knee, heart, liver, etc. Typical MR scans are essential now for better diagnosis but, limited resolution that is often inadequate for extracting detailed and reliable information. So, for the super resolution (SR) of MR brain images concepts of compressive sensing (CS) & fuzzy logical rules to improve data quality are proposed in this paper. Usually, reconstruction of an SR image is the formation of high resolution (HR) image which is obtained from one or few low resolution (LR) images. In the proposed method, with the help of compressive sensing a very limited number of images are considered even though it's a challenging task and fuzzy logical rules for a specific membership function are applied to improve the resolution of the image. To assess the performance of the proposal, different metrics are evaluated and achieved better results.


Subject(s)
Magnetic Resonance Imaging , Fuzzy Logic , Data Compression , Cerebrum/diagnostic imaging
2.
Braz. dent. j ; 27(6): 757-760, Nov.-Dec. 2016. tab
Article in English | LILACS | ID: biblio-828073

ABSTRACT

Abstract This study aimed to evaluate the accuracy of panoramic radiographs obtained by digital system based on charge coupled device (CCD) and a phosphor storage plate (PSP) system with two different file formats, JPEG irreversible type and BMP. Linear measurements of artificial bony defects were made in dry mandibles with a digital caliper. Measures of digital panoramic radiographs were taken in ImageJ(r) software. Each measurement was performed twice by an experienced examiner. The intra-rater agreement was considered very strong (Pearson's correlation coefficient of 0.97). There was no significant difference between the linear measurements of dry mandibles, considered the gold standard, in relation to measurements obtained from digital radiographs (p=0.47). The error of these measures for the CCD was 1.04 mm (9.97%) for JPEG images and 1.03 mm (9.99%) for those with BMP format. For the PSP images, these values were 1.48 mm (14.94%) and 1.43 mm (14.43%), respectively. Although there was no statistical difference between the images with JPEG and BMP format, for both digital systems (p=1.00 for CCD and p=0.98 for PSP system), errors made on radiographs obtained by PSP system were significantly higher than those of CCD (p<0.05). The size of the files saved in JPEG was also significantly lower (p=0.005) compared with the files saved in BMP. It may be concluded that the digital radiographs, both saved in JPEG and BMP formats, are accurate, regardless the used digital system, and JPEG images are more suitable for teleradiology.


Resumo Este estudo teve como objetivo avaliar a acurácia de radiografias panorâmicas digitais obtidas por sistema digital baseado em dispositivo acoplador de carga (DAC) e por sistema de placa de fósforo (PF) com duas diferentes extensões de arquivo (JPEG e BMP, sendo o primeiro do tipo compactador irreversível). Medidas lineares de defeitos ósseos foram realizadas em mandíbulas secas com paquímetro digital. As medidas correspondentes nas radiografias panorâmicas digitais foram realizadas no software ImageJ(r). As medidas foram realizadas duas vezes por um examinador. A concordância intraexaminador foi considerada muito forte (coeficiente de correlação de Pearson de 0,97). Não houve diferença significante entre as medidas lineares das mandíbulas secas, consideradas padrão-ouro, em relação às medidas obtidas das radiografias digitais (p=0,47). Os erros absolutos e relativos dessas medidas para o DAC foram de 1,04 mm (9,97%) para as imagens JPEG e de 1,03 mm (9,99%) para aquelas com extensão BMP. Para o sistema digital com PF esses valores foram de 1,48 mm (14,94%) e 1,43 mm (14,43%), respectivamente. Apesar de não ter havido diferença estatística entre as imagens com extensão JPEG e BMP, para ambos os sistemas digitais (p=1,00 para DAC e p=0,98 para a PF), os erros das medidas realizadas nas radiografias obtidas pelo sistema de PF foram significativamente maiores que os erros do DAC (p<0,05). O tamanho dos arquivos salvos em JPEG também foram significativamente menores (p=0,005) em comparação com os arquivos salvos em BMP. Pode-se concluir que as radiografias digitais tanto com extensão JPEG quanto BMP são acuradas, independente do sistema digital utilizado e as imagens salvas em JPEG são mais indicadas em telerradiologia.


Subject(s)
Data Compression , Radiography, Dental, Digital/methods , Radiography, Panoramic/methods
3.
Psicol. Estud. (Online) ; 21(2): 291-302, abr.-jun. 2016.
Article in English, Portuguese | LILACS, INDEXPSI | ID: biblio-1100243

ABSTRACT

A formação do conhecimento de senso comum é objeto de estudo da Teoria das Representações Sociais, que destaca o papel da comunicação na produção de sentidos pelos sujeitos. As imagens visuais favorecem a socialização de significados e são elementos ativos na formação das representações sociais. Frente ao expressivo papel das imagens na formação dos conteúdos representacionais, este relato visa apresentar um método de análise semiótica de imagens para a pesquisa em representações sociais. A análise semiótica de imagens foi selecionada como aporte teórico-metodológico, por oferecer os pressupostos necessários para o delineamento de um método de pesquisa eficaz para a identificação das representações sociais, a partir de signos icônicos, socialmente partilhados. O método de análise foi explorado por meio de procedimentos analíticos, empregados para a apreensão de representações sociais do feminino em cartazes de campanhas do Ministério da Saúde e que possibilitaram o acesso à rede de significados associados à imagem visual analisada. Destaca-se a pertinência do emprego da análise semiótica para a análise em representações sociais, que se apresenta como uma perspectiva fértil para novos estudos e que amplia as possibilidades de exploração dos conteúdos visuais.


The common sense knowledge formation is object of study of the Social Representation Theory, which highlights the role of communication in the production of comprehension by the subjects. The visual images favor the socialization of meanings and are active elements in the formation of social representations. Given the expressive role of the images in the formation of representational contents, this paper aims to present a semiotics analysis method for researches on social representations. The semiotic analysis of images was selected as a theoretical and methodological basis, for offering the means required for guidance for an effective research method to identify the social representations of socially shared iconic signs. The analysis method was explored by means of analytical procedures, employed for the apprehension of social representations of the feminine in posters for Brazilian Ministry of Health campaigns, which allowed access to the network of meanings associated with the analyzed visual image. It should be emphasized that the relevance of the use of semiotic analysis to analyze social representations, which presents itself as a fertile perspective for further studies expanding the possibilities of exploitation of visual content.


La formación del sentido común es el objeto de estudio de la Teoría de las Representaciones Sociales, lo que pone de relieve es la función de la comunicación en la creación de sentido por los sujetos. Las imágenes visuales favorecen la socialización de significados y son elementos activos en la formación de las representaciones sociales. Con interés en el importante papel de las imágenes en la formación de las representaciones sociales, este estudio tiene como objetivo presentar un método de análisis semiótico de las imágenes para la investigación sobre las representaciones sociales. El análisis semiótico de las imágenes fue seleccionado como fundamento teórico y metodológico al propiciar las condiciones necesarias para el diseño de un método eficaz para la investigación de las representaciones sociales de signos icónicos socialmente compartidos. El método de análisis se exploró por intermedio de los procedimientos analíticos empleados para la detección de las representaciones sociales del femenino en los carteles de campañas del Ministerio de Sanidad, lo que permitió el acceso a la red significados de significaciones asociadas a las imágenes visuales analizadas. Se destaca la importancia de la utilización del análisis semiótico en la investigación de las representaciones sociales, que se presenta como una perspectiva fértil para nuevos estudios y que amplía las posibilidades de exploración de los contenidos visuales.


Subject(s)
Female , Audiovisual Aids , Socialization , Advertising , Data Compression , Visual Perception , Breast Feeding , Women's Health , Communication , Comprehension
4.
Article in Chinese | WPRIM | ID: wpr-310291

ABSTRACT

<p><b>OBJECTIVE</b>To design and improve signal processing algorithms of ophthalmic ultrasonography based on FPGA.</p><p><b>METHODS</b>Achieved three signal processing modules: full parallel distributed dynamic filter, digital quadrature demodulation, logarithmic compression, using Verilog HDL hardware language in Quartus II.</p><p><b>RESULTS</b>Compared to the original system, the hardware cost is reduced, the whole image shows clearer and more information of the deep eyeball contained in the image, the depth of detection increases from 5 cm to 6 cm.</p><p><b>CONCLUSION</b>The new algorithms meet the design requirements and achieve the system's optimization that they can effectively improve the image quality of existing equipment.</p>


Subject(s)
Algorithms , Data Compression , Diagnostic Imaging , Ophthalmology , Signal Processing, Computer-Assisted , Ultrasonography
5.
Article in Chinese | WPRIM | ID: wpr-265606

ABSTRACT

The system applies H.264 compression coding technology and uses TCP/IP protocol to transmit data. It transfers the video information, cardio-spectrograms, blood oxygen and blood pressure spectrum to the medical area and the visiting area for families that outside of ICU intensively. The patients' information is transmitted to the medical staffs intensively, then making the relevant backups, so people can avoid many potential medical disputes.


Subject(s)
Blood Pressure , Data Compression , Heart , Humans , Intensive Care Units , Monitoring, Physiologic , Technology , Video Recording
6.
Article in Korean | WPRIM | ID: wpr-155183

ABSTRACT

PURPOSE: To evaluate the influence of image compression on optical coherence tomography (OCT) images in eyes with diabetic macular edema (DME). METHODS: Twenty eyes of 30 patients diagnosed with DME were included in this retrospective observational case series. Horizontal OCT scans centered at the center of the fovea were conducted using spectral-domain OCT (Spectral OCT/SLO(R)). The images were exported to Tag Image File Format (TIFF) and then transformed to 10, 5, and 1 quality of Joint Photographic Experts Group (JPEG) format using Photoshop. OCT images were taken before and after intravitreal bevacizumab injection. The presence of intraretinal fluid, foveolar detachment, and photoreceptor inner segment/outer segment (IS/OS) disruption were evaluated in each image. RESULTS: The mean (+/- standard deviation) size of TIFF images and 10, 5 and 1 quality JPEG images were 1712.0, 183.3 +/- 6.8, 90.9 +/- 4.3, 42.8 +/- 1.4 kilobytes (KB), respectively, before the injection and 1712.0, 189.5 +/- 9.1, 94.9 +/- 5.6, 43.4 +/- 1.8 KB, respectively, after the injection. The presence of intraretinal fluid, foveolar detachment, and photoreceptor IS/OS disruption identified in TIFF images was also identified in the compressed JPEG images. CONCLUSIONS: Quality of retinal OCT image did not influence the estimation of DME despite the JPEG image being compressed to approximately 1/40 of the original TIFF image size.


Subject(s)
Data Compression , Humans , Joints , Macular Edema , Retinaldehyde , Retrospective Studies , Tomography, Optical Coherence , Bevacizumab
7.
Biomédica (Bogotá) ; 33(1): 137-151, ene.-mar. 2013. ilus, tab
Article in Spanish | LILACS | ID: lil-675140

ABSTRACT

La medicina moderna es una actividad cada vez más compleja, basada en la información proveniente de múltiples fuentes: historias clínicas, dictáfonos e imágenes y vídeos provenientes de múltiples dispositivos. Las imágenes médicas constituyen una de las fuentes de mayor importancia, por cuanto ofrecen un apoyo integral del acto médico: el diagnóstico y el seguimiento. Sin embargo, la cantidad de información generada por los dispositivos de adquisición de imágenes sobrepasa rápidamente la disponibilidad de almacenamiento que tienen los servicios de radiología, lo cual genera costos adicionales en equipos de cómputo con mayor capacidad de almacenamiento. Además, la tendencia actual de desarrollo de aplicaciones en la "nube de cómputo", tiene limitaciones por cuanto, aunque el almacenamiento es virtual y está disponible desde cualquier sitio, la conexión se hace a través de internet. En estos dos casos, el uso óptimo de la información requiere necesariamente de algoritmos de compresión potentes y adaptados a las necesidades de la actividad médica. En este artículo se presenta una revisión de las técnicas de compresión más utilizadas para el almacenamiento de imágenes, así como un análisis crítico de éstas desde el punto de vista de su uso en ambientes clínicos.


Modern medicine is an increasingly complex activity , based on the evidence ; it consists of information from multiple sources : medical record text , sound recordings , images and videos generated by a large number of devices . Medical imaging is one of the most important sources of information since they offer comprehensive support of medical procedures for diagnosis and follow-up . However , the amount of information generated by image capturing gadgets quickly exceeds storage availability in radiology services , generating additional costs in devices with greater storage capacity . Besides , the current trend of developing applications in cloud computing has limitations, even though virtual storage is available from anywhere, connections are made through internet . In these scenarios the optimal use of information necessarily requires powerful compression algorithms adapted to medical activity needs . In this paper we present a review of compression techniques used for image storage , and a critical analysis of them from the point of view of their use in clinical settings.


Subject(s)
Humans , Data Compression/methods , Diagnostic Imaging/methods , Algorithms , Information Storage and Retrieval , Visual Perception/physiology
8.
Article in Chinese | WPRIM | ID: wpr-264241

ABSTRACT

This paper introduces the implement method of DICOM medical image compression technology, The image part of DICOM files are extracted and converted to BMP format. The non-image information in DICOM file are stored into the text. When the final image of JPEG standard and non-image information are encapsulated to DICOM format images, it realizes the compression of medical image, which is beneficial to the image storage and transmission.


Subject(s)
Data Compression , Methods , Image Processing, Computer-Assisted , Methods , Software
9.
Article in Chinese | WPRIM | ID: wpr-232739

ABSTRACT

Low-dose computed tomography (CT) reconstruction has become the focus of X-ray CT imaging study. In this paper, we propose an improved prior image constrained compressed sensing (PICCS) reconstruction approach. A penalized weighted least-squares approach was adopted to realize the line integral projection (sinogram) data restoration, followed by filtered back-projection (FBP) of the restored sinogram data for image reconstruction. Finally, the FBP image as the prior image was used for PICCS approach for dose reduction. Qualitative and quantitative evaluations were carried out with computer simulation. The results showed that the present approach yielded noticeable gains over the original PICCS approach for dose reduction in terms of noise-induced artifacts suppression and edge detail preservation.


Subject(s)
Algorithms , Computer Simulation , Data Compression , Methods , Image Processing, Computer-Assisted , Methods , Least-Squares Analysis , Phantoms, Imaging , Radiation Dosage , Signal-To-Noise Ratio , Tomography, X-Ray Computed , Methods
10.
Article in Chinese | WPRIM | ID: wpr-325967

ABSTRACT

This paper combined the coded excitation with the technique of ophthalmic high-frequency ultrasonic imaging, and raised a new high-velocity data detection and signal processing method. 16 bit Golay complementarity sequences were produced by FPGA, which excited the probe to produce ultrasonic waves. Data detection circuit achieved the digitalized of the 15 MHz high-frequency ultrasonic echo signals in real time. Sampling rate was 120MHz, and sampling bit was 14 bit. Decoded compression arithmetic was realized by FPGA in real time, in which A code compression was alternated with B code compression. The return echo was correlated with the corresponding decode filter A and filter B respectively, and then the echo was delayed and summed to complete the decoding process. The experiment indicated that coded excitation can effectively increase the range of mainlobe and decrease the range of sidelobe. This technique can effectively raise the signal-to-noise ratio, and has significant research value in advancing the ophthalmic ultrasonic image quality and raising the safety of the equipment.


Subject(s)
Data Compression , Diagnostic Techniques, Ophthalmological , Signal Processing, Computer-Assisted , Ultrasonography , Methods
11.
Article in Chinese | WPRIM | ID: wpr-244614

ABSTRACT

In this paper is proposed a new method that approximates line segment with angle to control line as a basis for improving radial fitting. Experiments on selected records from the Massachusettes Institute of Technology and Boston's Beth Isral Hospital (MIT-BIH) arrhythmia database have revealed that the improved algorithm not only increases computation quantity, but also improves approximating quality and potentiates Real-time application of the linear approximation distance thresholding (LADT).


Subject(s)
Algorithms , Data Compression , Electrocardiography , Methods , Humans , Signal Processing, Computer-Assisted
12.
Rev. chil. radiol ; 15(supl.1): 10-16, 2009. ilus
Article in Spanish | LILACS | ID: lil-577473

ABSTRACT

Introduction: The acquisition process in magnetic resonance images (MRI) is slow. One approach to reduce the acquisition times is the reconstruction of undersampled data. i.e. to acquire less samples that those needed for standard application, and to reconstruct the unknown samples using mathematical algorithms. We propose to used reconstruction techniques for undersampled data based on Compressed Sensing (CS) to decrease the acquisition times, obtaining identical MRI as those obtained with all samples. Methods: We performed reconstructions of undersampled data obtained from phantoms and MRI with 60 percent, 55 percent and 50 percent of the samples. Results: When the number of samples was more that the double of pixels with non cero intensity, the reconstructions where identical to the original ones. For the MRI experiment, this was achieved with 60 percent of the samples, therefore obtaining a 40 percent of reduction in the acquisition time. Discussion: Our reconstruction technique based on CS is an effective way for reducing the acquisition times in MRI.


Introducción: El proceso de adquisición de imágenes por resonancia magnética (IRM) es lento. Una forma para disminuir los tiempos de adquisición es a través de reconstrucciones de datos submuestreados, es decir tomar menos muestras que las necesarias en aplicaciones estándares, y reconstruir las muestras faltantes a través de algoritmos matemáticos. Proponemos utilizar técnicas de reconstrucción de datos submuestreados basadas en técnicas de Compressed Sensing (CS) para disminuir los tiempos de adquisición, obteniendo imágenes idénticas a las obtenidas con todas las muestras. Métodos: Realizamos reconstrucciones de datos submuestreados de fantomas y IRM con 60 por ciento, 55 por ciento y 50 por ciento de las muestras. Resultados: Cuando el número de muestras fue mayor al doble del número de pixeles con intensidad cero, las reconstrucciones obtenidas fueron idénticas a las originales. Para las IRM esto se logró con 60 por ciento de las muestras, logrando reducciones del 40 por ciento en los tiempos de adquisición. Discusión: Nuestra técnica de reconstrucción basada en CS es una forma efectiva para reducir los tiempos de adquisición de IRM.


Subject(s)
Humans , Magnetic Resonance Imaging/methods , Image Processing, Computer-Assisted/methods , Image Enhancement/methods , Data Compression/methods , Time Factors , Phantoms, Imaging , Magnetic Resonance Imaging/instrumentation , False Negative Reactions , False Positive Reactions , Predictive Value of Tests
13.
Article in Chinese | WPRIM | ID: wpr-280227

ABSTRACT

In view of the fact that the large quantities of data contained in the medical image do not have a favorable setting for effective storage and transmission in the existing network, we have developed a JPEG2000 DICOM image compression kit using VC++, and we have realized the medical image storage service according to the C-STORE rule of DICOM standard. The results showed that the medical image processed by JPEG2000 compression algorithm not only greatly saved the storage space, but also reduced the band width needed by transmission. In this paper is discussed the DICOM image compressed by JPEG2000 compression algorithm in DICOM strorage service application. The significance of JPEG2000 compression algorithm in the development of picutre archiving and communication systems (PACS) and telemedicine is also explained.


Subject(s)
Algorithms , Computer Communication Networks , Data Compression , Diagnostic Imaging , Humans , Image Processing, Computer-Assisted , Medical Records Systems, Computerized
14.
Journal of Biomedical Engineering ; (6): 1178-1183, 2008.
Article in Chinese | WPRIM | ID: wpr-318189

ABSTRACT

A Fast Multi-resolution Volume Rendering Method (FMVRM) based on wavelet and Shear-Warp is herein proposed. In this method, the medical volume data is compressed using wavelet transformation first. Then based on the set resolution, the medical volume data is decompressed guided by Opacity transfer function (OTF). Finally, the 3D medical image is reconstructed on the basis of Shear-Warp using Block-based run length encoded (BRLE) data structure, in which, the aliasing artifacts resulting from under-sampling in Shear-Warp is avoided by the pre-integrated volume rendering technology. Experiments demonstrate the good performance of the proposed method.


Subject(s)
Algorithms , Artifacts , Data Compression , Methods , Humans , Imaging, Three-Dimensional , Methods
15.
Article in Chinese | WPRIM | ID: wpr-291257

ABSTRACT

The method of subblock coding for medical image compression is presented by means of the integer lifting wavelet transform. The integer lifting wavelet transform has better effects on improving the processing speed; it can achieve wavelet transform for arbitrary size image and accomplish the transform at current position; furthermore, it can save memory space. The lifting algorithm can deal with the lossless compression and loss compression of image simultaneously, so it is adapted to telemedicine system and medical image compression system. The compression method based on image subblock coding can not only realize controlling BR (bit ratio), but also realize SNR (signal noise ratio) and suit for progressive transform.


Subject(s)
Algorithms , Data Compression , Methods , Humans , Image Interpretation, Computer-Assisted , Methods , Information Storage and Retrieval , Methods
16.
Article in Chinese | WPRIM | ID: wpr-230667

ABSTRACT

A video image recorder to record video picture for wireless capsule endoscopes was designed. TMS320C6211 DSP of Texas Instruments Inc. is the core processor of this system. Images are periodically acquired from Composite Video Broadcast Signal (CVBS) source and scaled by video decoder (SAA7114H). Video data is transported from high speed buffer First-in First-out (FIFO) to Digital Signal Processor (DSP) under the control of Complex Programmable Logic Device (CPLD). This paper adopts JPEG algorithm for image coding, and the compressed data in DSP was stored to Compact Flash (CF) card. TMS320C6211 DSP is mainly used for image compression and data transporting. Fast Discrete Cosine Transform (DCT) algorithm and fast coefficient quantization algorithm are used to accelerate operation speed of DSP and decrease the executing code. At the same time, proper address is assigned for each memory, which has different speed;the memory structure is also optimized. In addition, this system uses plenty of Extended Direct Memory Access (EDMA) to transport and process image data, which results in stable and high performance.


Subject(s)
Algorithms , Capsule Endoscopy , Methods , Data Compression , Methods , Equipment Design , Humans , Image Processing, Computer-Assisted , Methods , Signal Processing, Computer-Assisted , Software
17.
Article in Chinese | WPRIM | ID: wpr-342742

ABSTRACT

Now researches of ECG data compression mainly focus on compressing the ECG data of low sampling rate. A BW-based high sampling rate ECG data lossless compression algorithm is proposed in this paper. We apply difference operation to the original ECG data first and take part of the 16-bit binary differential value as 8-bit binary. Then the differential results are coded with the move-to-front coding method in order to make the same characters centralizing in a certain area. Last, we gain a high compression ratio by using the arithmetic coding method further. Our experimental results indicate that this is an efficient lossless compression method suitable for body surface ECG data as well as for heart ECG data. The average compression ratios come up to 3.547 and 3.608, respectively. By comparison with current ECG compression algorithms, our algorithm has gained much improvement in terms of the compression ratio, especially when applied to the high sampling rate ECG data.


Subject(s)
Algorithms , Data Compression , Electrocardiography , Methods , Humans , Signal Processing, Computer-Assisted
18.
Journal of Biomedical Engineering ; (6): 1027-1044, 2007.
Article in Chinese | WPRIM | ID: wpr-346018

ABSTRACT

To objectively and quantitatively study the effect of JPEG2000 lossy compression of nuclear medicine image, line source images of various noise levels, actual quadrant-bar phantom images and simulated quadrant-bar phantom images of various noise levels were compressed using a JPEG2000 plug-in at 10 : 1 to 50 : 1 with a 10 : 1 step. Modulation transfer function (MTF), full width at half-maximum (FWHM) and the peak to total count ratio (PTCR) of line spread function of the simulated line source images were analyzed quantitatively. Image quality of the quadrant-bar phantom images was visually evaluated according to quality control procedures and the result was used to verify the quantitative analysis. It was observed that PTCR decreased as compression ratio increased and the higher the noise level, the faster PTCR decreased, which was in accordance with the increase of the width of the smallest bars that can be visually resolved in the actual quadrant-bar phantom images and simulated quadrant-bar phantom images. On the other hand, no significant change of MTF and FWHM was observed as compression ratio increased. It was concluded that PTCR may serve as an objectively quantitative metrics of image quality assessment.


Subject(s)
Algorithms , Data Compression , Methods , Reference Standards , Diagnostic Imaging , Reference Standards , Humans , Image Processing, Computer-Assisted , Nuclear Medicine , Methods
19.
Article in Korean | WPRIM | ID: wpr-187733

ABSTRACT

PURPOSE: To determine the usefulness of compression standard JPEG2000 for compression of mammographic images. MATERIALS AND METHODS: Image of a mammographic phantom was compressed using JPEG2000 at ratios of 10:1, 20:1, 30:1, 40:1, 50:1 and 60:1. The sizes of the images were compared, and scores were recorded by counting the numbers of fibers, groups of specks and masses seen in each phantom image. More than four fibers, three groups of specks and three masses and a total score of 10 were considered acceptable. RESULTS: The size of a DICOM image was 17,042 KB, a TIFF image was 8,324 KB, the original JPEG image was 1,506 KB and the most compressed image (50:1) above an acceptable total score of 10 was 43 KB. In each category, the compression image of fiber was acceptable up to compression ratio of 50:1 (score of 5), groups of specks was acceptable up to 60:1 (score of 3) and mass was acceptable up to 50:1 (score of 3.5). The total score, which was acquired by adding up the individual scores of all three categories, for a compression ratio of 50:1 was 12 and was acceptable, but the total score for 60:1 was 8 and was not acceptable. CONCLUSION: The compression standard JPEG2000 is an efficient means for compressing mammographic images at high ratios without compromising diagnostic value.


Subject(s)
Data Compression
20.
Rev. imagem ; 28(1): 13-18, jan.-mar. 2006. ilus, graf, tab
Article in Portuguese | LILACS | ID: lil-510361

ABSTRACT

OBJETIVO: Estabelecer o limite máximo de compactação JPEG na qual não há comprometimento na análise quantitativa de lesões vasculares cerebrais isquêmicas de pequenos vasos em ressonância magnética. MATERIAL E MÉTODO: Quinze imagens em DICOM foram convertidas para JPEG a taxas de compressão de 1:10 a 1:60 e avaliadas juntamente com as originais por três neurorradiologistas, que identificaram as lesões, tipo de contorno, morfologia e intensidade do sinal. RESULTADOS: As lesões foram bem identificadas até a taxa de 1:30. Foram identificadas mais lesôes na taxa de 1:10 do que nas imagens originais. Morfologia e contornos foram bem avaliados até a taxa de 1:40. A compactação não alterou o sinal. CONCLUSÃO: Foram avaliadas lesôes pequenas (até 2mm) e notamos que em todas as taxas de compactação o algoritmo gerou ruídos na imagem, que levaram os avaliadores a identificarem mais lesões nas imagens JPEG do que nas imagens originais DICOM, criando falso-positivos.


OBJECTIVE: To establish the maximum achievable JPEG compression ratio without affecting quantitative and qualitative magnetic resonance imaging analysis of isquemic lesions in small vessels of the brain. MATERIAL AND METHOD: Fifteen DICOM images were converted to JPEG with a compression ratio of 1:10 to 1:60 and were assessed together with the original images by three neuroradiologists. The number, morphology, edges and signal intensity of the lesions were analyzed. RESULTS: Lesions were properly identified up to a 1:30 ratio. More lesions were identified with a 1:10 ratio then in the original images. Morphology and edges were properly evaluated up to a 1:40 ratio. Compression did not affect signal. CONCLUSION: Small lesions were identified (<2mm) and in all compression ratios JPEG algorithm generated image noise that misled observers to identify more lesions in JPEG images then in DICOM images, thus generating false-positive results.


Subject(s)
Humans , Data Compression , Fourier Analysis , Information Storage and Retrieval , Information Systems , Magnetic Resonance Imaging , Cerebrovascular Disorders/diagnosis , Qualitative Research , Evaluation Studies as Topic
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