what is the source of contrast (what creates the signal) in the image?
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- Contrast sensitivity is the ability of an imaging process to produce an image of objects or tissues in the body that have relatively small physical differences or inherent contrast. The contrast that is to be imaged is in the form of some specific physical characteristic.
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- The source of the MRI signal is the hydrogen proton. After a person is placed in the MRI scanner, a powerful magnetic field is applied. This causes the spins of hydrogen protons to align with the field, rather than having a random orientation.
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Primary color The emission spectra of the three phosphors that define the additive primary colors of a CRT color video display. Unlike subtractive systems that use magenta, yellow, and cyan inks, additive systems such as computer displays mix red, green, and blue light to make all colors.
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X-Ray The images produced by X-rays are due to the different absorption rates of different tissues. Calcium in bones absorbs X-rays the most, so bones look white on a film recording of the X-ray image, called a radiograph. Fat and other soft tissues absorb less, and look gray.
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Basic principles of computed axial tomography This latter form of computed tomography is called emission computed tomography, in contrast to transmission computed tomography, in which the sectional images represent the spatial dis- tribution of the attenuation of x-rays in the tissues examined.
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Michelson contrast, RMS contrast and energy of various spatial stimuli at threshold Contrast sensitivity was expressed in terms of Michelson contrast, RMS contrast, and contrast energy in order to demonstrate the characteristics of various contrast measures.Gratings and noise stimuli had either constant stimulus area or constant number of cycles.ichelson contrast sensitivity was better for gratings than for noise stimuli or spots, whereas RMS contrast sensitivity was almost equal for gratings and noise stimuli but lowest for spots.
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CT scan You may have the contrast medium by injection either instead of, or as well as, the drink. The contrast medium makes the digestive system (gut) show up more clearly in the scan. Below is an example of a CT scan of the abdomen.
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Contrast ratio The contrast ratio is a property of a display system, defined as the ratio of the luminance of the brightest color to that of the darkest color that the system is capable of producing. A high contrast ratio is a desired aspect of any display. It has similarities with dynamic range. There is no official, standardized way to measure contrast ratio for a system or its parts, nor is there a standard for defining Contrast Ratio that is accepted by any standards organization so ratings provided by d
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GUIDE TO IMAGE SHARPENING (1) Capture sharpening aims to address any blurring caused by your image's source, while also taking image noise and detail into consideration. With digital cameras, such blurring is caused by the camera sensor's anti-aliasing filter and demosaicing process, in addition to your camera's lens.
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Patterns of Contrast Enhancement in the Brain and Meninges Contrast material enhancement in the central nervous system (CNS) is a combination of two primary processes: intravascular (vascular) enhancement and interstitial (extravascular) enhancement (1,2). Intravascular enhancement may reflect neovascularity, vasodilatation or hyperemia, and shortened transit time or shunting.
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- Contrast medium. A medical contrast medium (or contrast agent) is a substance used to enhance the contrast of structures or fluids within the body in medical imaging. It is commonly used to enhance the visibility of blood vessels and the gastrointestinal tract.
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Information About Intravenous and Oral Contrast Used in CT About contrast agents. CT contrast are agents (liquids) and are sometimes referred to as dye. CT contrast is used to make specific organs, blood vessels and/or tissue types stand out with more image contrast to better show the presence of disease or injury. Thus CT contrast highlights specific areas of the resultant CT image or dyes it. imaginis.com.
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- Contrast = ( B1 - B2 ) x 100 / B1. B1 = light reflectance value (LRV) of lighter area. B2 = light reflectance value (LRV) of darker area. Our experience has shown that the 70% figure is not a magic number. Contrasts of a few percentage points below the recommended figure, depending on the colors chosen, can often yield legible results.
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- Rayleigh criterion: two optical images are separable if central bright spot of one image falls on first dark band of second. Real image: optical image at which rays from object converge. Receiver: device that detects electromagnetic waves.
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- The resulting bands of light and dark cause imperfections in a text document or an image. Because every printer has its own unique pattern of banding, or intrinsic signature, the imperfections can be exploited to trace a document to the printer on which it was created, Chiu said.
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- The small, free radical molecule nitric oxide (NO; N=O) has been identified as a major signal transduction molecule in vertebrates (animals). NO is derived from arginine in two steps catalyzed by nitric oxide synthase (NOS; EC 1.14.13.39). NOS catalyzes the net reaction:
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- An ideal low-pass filter with cutoff frequency wc rad/sec. is used to obtain the reconstructed signal xr(t) . Suppose the highest-frequency component in x(t) is at frequency wm. Then the Sampling Theorem states that for ws wm there is no loss of information in sampling.
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X-ray 1 Structures that are dense (such as bone) will block most of the x-ray particles, and will appear white.  Metal and contrast media (special dye used to highlight areas of the body) will also appear white.
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- Sources with CRI values less than 50 are generally regarded as rendering colors poorly, that is, colors may appear unnatural. correlated color temperature (CCT) - A specification for white light sources used to describe the dominant color tone along the dimension from warm (yellows and reds) to cool (blue).
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First Shot of Civil War fired at Fort Sumter from Charleston, South Carolina USA (1861) Civil War maps of Fort Sumter + Charleston SC. Scale model of Fort Sumter in Charleston SC harbor (Before the Civil War). Details of layout at Fort Sumter in Charleston SC harbor (Before Civil War). Painting of Fort Sumter burning in Charleston SC harbor on April 12, 1861. Fort Johnson view of Fort Sumter-First Shot of Civil War was Fired HERE! Fort Sumter attack on April 13, 1861 shown in Harper's Weekly newspaper.
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- Don't Take Contrast Ratio Too Seriously. Contrast ratio is the ratio between the brightness of the brightest and darkest areas a projector can produce. All other things being equal, a higher contrast ratio indicates more vibrant, eye-catching colors and more detail showing in dark areas on the screen.
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- 1 CT scan. 2  When a CT is used to image the spine, you may have a contrast dye injected into your spinal canal before the X-rays are taken — a procedure called a CT myelogram. 3  The dye then circulates around your spinal cord and spinal nerves, which appear white on the scan. 4  Electromyography (EMG).
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Basic Physics of Digital Radiography/The Image The maximum spatial resolution of an imaging system can be readily obtained by imaging a resolution test object-an example of which is shown in Figure 6.5, panel (a). The test object consists of narrow parallel slits in a lead sheet at spacings which decrease to beyond the maximum resolution of the image receptor.
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What causes the faint horizontal lines on my monitor? You can see a faint horizontal line just above the tip of the cursor. Most likely, you have purchased a Cathode Ray Tube (CRT) monitor based on Sony's Trinitron technology. These monitors use an aperture grill instead of a shadow mask, and the aperture grill causes the lines. You can see the line in the following photo:To understand why the lines are there, we need to look at the shadow mask and aperture grill systems and understand the differences between them. 1  Shadow mask: The shadow mask in a CRT monitor is a metal screen filled with holes that sits just behind the phosphor layer.hese monitors use an aperture grill instead of a shadow mask, and the aperture grill causes the lines. You can see the line in the following photo: To understand why the lines are there, we need to look at the shadow mask and aperture grill systems and understand the differences between them.
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Contrast Contrast can have many different meanings even in radiography. I will be describing image contrast. First let’s define image contrast: Image contrast is the difference between adjacent densities.The adjacent densities can range from white to black and various shades of grey in between.ontrast can have many different meanings even in radiography. I will be describing image contrast. First let’s define image contrast: Image contrast is the difference between adjacent densities.
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Photoplethysmogram The DC component of the signal is attributable to the bulk absorption of the skin tissue, while the AC component is directly attributable to variation in blood volume in the skin caused by the pressure pulse of the cardiac cycle.