
	Where results make sense

Topic: Image frequency

Related Topics

Internal ballistics

Conic section

Gunnery

Force field

External ballistics

Ballistics

In the News (Mon 4 Jun 12)

EXECUTIVE POWER

Iran

ANALYSIS

Pakistan

Family compact

	Superheterodyne Receivers - Microwave Encyclopedia - Microwaves101.com
		The sum frequency is the upper sideband, and the difference frequency is the difference sideband.
		The device that converts the incoming RF frequency to intermediate frequency is called a mixer.
		Image noise foldover can be prevented in two ways: use an image filter, or use an image-rejection mixer.
	www.microwaves101.com /encyclopedia/receivers_superhet.cfm (1527 words)

	Image frequency - Wikipedia, the free encyclopedia
		Image frequency: In radio reception using heterodyning in the tuning process, an undesired input frequency that is capable of producing the same intermediate frequency (IF) that the desired input frequency produces.
		In a heterodyne receiver system, the mixer accepts two inputs, the signal to be detected and the local oscillator, at frequencies f
		The term image arises from the mirror-like symmetry of the detectable signal frequencies about the beating-oscillator frequency.
	en.wikipedia.org /wiki/Image_frequency (150 words)

	U.S. Patent: 5566284 - Apparatus and method for mip-map generation using low-pass filtering based on resolution ratio - ...
		A spatial low-pass filter allows the components of lower frequencies of the spatial frequency image data to pass therethrough using a cutoff frequency corresponding to the resolution ratios of the texture.
		The size of the image block is preferably selected from the range of 8 to 16 pixels in both directions, in view of the transformation efficiency of the discrete cosine transformation and the inverse discrete cosine transformation.
		The size of an image block is preferably selected from the range of 8 to 16 pixels in each of the horizontal and vertical directions, in view of the transform efficiency of the discrete cosine transformation and the inverse discrete cosine transformation.
	www.everypatent.com /comp/pat5566284.html (6590 words)

	Method and apparatus for encoding frequency components of image information - Patent 5162923
		An image encoding method, and an apparatus therefor, enabling rapid comprehension of the outline of the entire image promptly, at the decoding of the encoded image information, and also an image encoding method, and an apparatus therefor, capable of efficient encoding adapted for the state of the image to be encoded.
		Image information is divided into plural block, each consisting of plural pixels, the frequency of the image in each block is analyzed, the frequency components of the image in each block are separated into plural bands, and the frequency components contained in each of said plural bands are encoded.
		Subsequently the image of the band 2 or the intermediate frequency component is superposed, and finally the image of the band 3 or the high frequency component is superposed.
	www.freepatentsonline.com /5162923.html (12596 words)

	Image rejection ratio - Wikipedia, the free encyclopedia
		In reception using heterodyning in the tuning process, the image rejection ratio, or image frequency rejection ratio, is the ratio of (a) the intermediate-frequency (IF) signal level produced by the desired input frequency to (b) that produced by the image frequency.
		The image rejection ratio is usually expressed in dB.
		When the image rejection ratio is measured, the input signal levels of the desired and image frequencies must be equal for the measurement to be meaningful.
	en.wikipedia.org /wiki/Image_rejection_ratio (143 words)

	Engineering Dictionary, Radar terms, and definitions 'I'
		The image frequency is located at the same frequency difference ()f) to one side of the local oscillator as the tuned (desired) frequency is to the other side.
		An undesired signal received at the image frequency by a superheterodyne receiver not having pre-selection would, therefore, mix (beat) with the oscillator, produce the proper receiver IF, and be processed in the same manner as a signal at the desired frequency.
		Image jamming inverts the phase of the response and is thereby useful as an angle deception technique.
	www.interfacebus.com /Electronic_Dictionary_Radar_Terms_I.html (632 words)

	FFREQ -- Frequency Domain Image Filter
		In order to reduce artifacts in the filtered image caused by sharp cutoffs in the frequency image, FFREQ automatically generates a smooth border at the boundaries of the mask regions so that the filter gain goes from 0 to 1 gradually within the border.
		For a real image, its Fourier transform exhibits a property of conjugate symmetry about the center of the image (at a pair of corresponding points, the real parts of the Fourier transform are equal and the imaginary parts have the same magnitude but opposite signs).
		For Fourier transformed images, the zero frequency position is assumed to be at the center of the image.
	www.pcigeomatics.com /cgi-bin/pcihlp/FFREQ (953 words)

	Image Manipulation and Analysis Techniques
		An image represented by 4000 x 3200 pixels has a higher resolution than the same image represented by 1000 x 800 pixels, because in the former, the higher number of pixels can represent more detail and hence the resolving power is greater.
		The Erosion filter is a morphological filter that changes the shape of objects in an image by eroding (reducing) the boundaries of bright objects, and enlarging the boundaries of dark ones.
		The frequency magnitude is determined by the brightness of the pixel at a particular point.
	www.lab.anhb.uwa.edu.au /hb313/main_pages/timetable/lectures/imageanalysis.htm (1917 words)

	Imagine the Universe! Dictionary
		This period of the star's life is characterized by loss of mass from its surface in the form of a stellar wind.
		Frequency is often measured in Hertz (Hz), where a wave with a frequency of 1 Hz will pass by at 1 cycle per second.
		The derived SI unit of frequency, defined as a frequency of 1 cycle per second.
	imagine.gsfc.nasa.gov /docs/dict_ei.html (2673 words)

	CHAPTER-11
		The frequency of the waves will be related to the position in the frequency encoding direction and the variation in phase of the waves will be related to the position in the phase encoding direction.
		is the resonance frequency of a nucleus and
		In the image of the head, the nose extends beyond the field of view on the left, and its imaged position is wrapped around and appears on the right of the image.
	www.cis.rit.edu /htbooks/mri/chap-11/chap-11.htm (3697 words)

	The nPhaze Boys Official Site - Their Research (Site not responding. Last check: 2007-10-26)
		The frequency domain representation of an image serves as a stronger channel for transmitting information covertly while minimizing distortion of the container image.
		Frequency methods encode the data across the global frequencies of the image.
		The key variables, r and alpha, are needed to extract the text from the attacked image using textextract().
	www.owlnet.rice.edu /~rwagner/steg3.html (1376 words)

	Fourier Domain Operations
		Clearly, at any given frequency in the DFT of the image, a large magnitude implies a greater prevalance of a sinusoid at that frequency in the image while a small magnitude implies less of a sinusoid at that frequency is present in the image.
		The magnitude of the dog image is combined with the phase of the fish in the left image, and the magnitude of the fish image is combined with the phase of the dog image in the right image below.
		As stated earlier, the magnitude determines how intense a sinusoid of a given frequency is in the image, but the phase determines how the peaks and valleys of a given sinusoid are shifted across the image.
	www.cs.unc.edu /~parente/igv/hw5/parente_hw5.html (937 words)

	Card recording medium, certifying method and apparatus for the recording medium, forming system for recording medium, ...
		Since the frequency spectrum containing the ID information is subjected to inverse frequency transformation and then the frequency spectrum having the ID information hidden therein and the frequency spectrum of the original work are differentiated, whereby the ID information is generated.
		Subsequently, the frequency spectrum data of the ID information 83 is subtracted from the image signal which has been subjected to DCT, and the transformation which is opposite to that of the DCT means 85 is performed on the subtraction result in the inverse DCT means 87 to obtain an extraction pattern 88.
		The read-in image data are separated into the photograph portion and the mentioned-item portion in the capture 310, and the these portions are output to the DCT unit 320 and the character recognizer 330 respectively.
	www.freepatentsonline.com /6024287.html (11683 words)

	Olympus FluoView Resource Center: Digital Image Sampling Frequency - Interactive Java Tutorial (Site not responding. Last check: 2007-10-26)
		The spatial resolution of a digital image is determined by the distance between pixels, known as the sampling interval, and the accuracy of the digitizing device.
		In cases where pixels generated by the digitizer are spaced too far apart compared to the high-frequency detail of the image, this specimen information may then masquerade as lower spatial frequency image features that are not actually present in the specimen.
		It should be noted that while the spatial frequency of the resultant image is artifactually altered by aliasing, the amplitude of the signal is not significantly changed.
	www.olympusfluoview.com /java/samplefrequency (897 words)

	Scanners and sharpening: resolution and MTF
		The first sensor null (the frequency where a complete cycle of the signal covers one sample, hence must be zero regardless of phase) is twice the Nyquist frequency.
		In a fuzzy image, there won't be much response left at dscan/2, but you can still sharpen (though not as much) by setting R (the number of pixels between the original image and the replica used for sharpening) larger than 1, which drops the frequency of maximum boost.
		This image is for a 4000 dpi scan of Velvia with the excellent 35mm lens with sharpening constant ksharp = 0.54.
	www.normankoren.com /Tutorials/MTF2.html (5419 words)

	Image spatial frequency resolution (Site not responding. Last check: 2007-10-26)
		Experimentally, an image of sinusoidal intensity is displayed and the contrast varied until the viewer can see the bar pattern.
		I am interested in spatial frequency resolution as in, ability to resolve adjacent spatial frequncies (I think this is closer to a normal definition of 'frequency resolution').
		I think this will be related to the 'size' of the image relative to the detail within it - similar to 1D DSP where the 'total sampling time' determines the frequency resolution.
	talkaboutelectronicequipment.com /group/comp.dsp/messages/188641.html (225 words)

	Image & Look
		The Olympic Rings and the image elements of the Beijing Olympic Games, whose design has been completed, symbolize the Olympic Spirit and the concepts of this edition of the Olympic Games, and serve as the basis for the creation of the Beijing 2008 Olympic Games Image and Look.
		They are the carrier to showcase to the world the culture and tradition, as well as the city images and human spirit of China and Beijing.
		The Olympic symbol consists of five interlaced rings of equal dimensions (the Olympic rings), used alone, in one or in five different colours, which are, from left to right, blue, yellow, fl, green and red.
	en.beijing2008.cn /62/67/column211716762.shtml (496 words)

	Image Noise: Examples and Characteristics
		This means that images which are underexposed will have more visible noise-- even if you brighten them up to a more natural level afterwards.
		On the other hand, overexposed images will have less noise and can actually be advantageous, assuming that you can darken them later and that no region has become solid white where there should be texture (see "Understanding Histograms, Part 1").
		The term "fine-grained" was used frequently with film to describe noise whose fluctuations occur over short distances, which is the same as having a high spatial frequency.
	www.cambridgeincolour.com /tutorials/noise2.htm (927 words)

	Frequency and Spatially Adaptive Wavelet Packets
		Previously [2][3], wavelet packets have been used to arbitrarily partition the image frequency plane to adapt to signal frequency characteristics.
		Alternatively, the frequency bands themselves may be partitioned [4][5] and coded separately using fixed spatial segmentations.
		To accommodate all combinations of frequency and spatial splits, all nodes in the tree must be split both spatially and by frequency.
	ctr.columbia.edu /~jrsmith/html/pubs/ICASSP-95/wavepack_final_1.html (2023 words)

	GLOSSARY I
		NOTE: An image frequency is a frequency which differs from, but has a certain symmetrical relationship to, that which a superheterodyne receiver is tuned.
		8] (2) Jamming the image frequency of a monopulse radar causing the antenna to be driven away from the target.
		The image is formed from the temperature differences between targets and the background of the scene.
	www.sew-lexicon.com /gloss_i.htm (4225 words)

	9.4 Filtering in the frequency domain (Site not responding. Last check: 2007-10-26)
		One common motive to generate image frequency data is to filter the data.
		The two methods of creating a filter mask are to transform a convolution mask from the spatial domain to the frequency domain or to calculate a mask within the frequency domain.
		The frequencies in this region are multiplied by 1.0 and therefore pass unaffected.
	www.netnam.vn /unescocourse/computervision/94.htm (882 words)

	Using polyphase filters as image attenuators
		However, a low IF keeps the image frequency so close to the target frequency that suppressing the image in front of the mixer would require an impossibly high Q of the filter preceding the mixer.
		Image rejection is then achieved by an image rejector that shifts the phase of one filter's output by an additional 90° and adds it with the second filter's output.
		The third advantage of polyphase filters is that, for the same degree of image suppression, the matching of their components is less stringent than the required matching in two separate IF filters and in the subsequent image rejector.
	rfdesign.com /mag/radio_using_polyphase_filters/index.html (2483 words)

	Filtering Images in the Frequency Domain
		A -1 argument to the FFT function indicates a transformation from the spatial to the frequency domain, and a 1 indicates the reverse transformation.
		In general, the low frequency terms usually represent the general shape of the image and the high frequency terms are needed to sharpen the edges and provide fine detail.
		Different frequencies are represented at different distances from the origin (usually represented as the center of the image) and different directions from the origin represent different orientations of features in the original image.
	www.dfanning.com /ip_tips/freqfiltering.html (840 words)

	A Low-Frequency Atlas of the Galactic Center
		This image is the largest and most sensitive radio image ever made of the Milky Way's center at a uniform and high resolution.
		This image has also led to the discovery of many new sources, including a new supernova remnant, numerous pulsar candidates, and several new filamentary structures.
		We are also using this image as the initial epoch in a series of ongoing observations intended to monitor the variable and transient source populations at the Galactic center.
	rsd-www.nrl.navy.mil /7213/lazio/GC (766 words)

Try your search on: Qwika (all wikis)