The Super Famicom Naizou TV SF1 ( スーパーファミコン内蔵テレビSF1 , Sūpā Famikon Naizou Terebi SF1 ) (often described as the SF1 SNES TV ) is a television set produced by Sharp Corporation with a built-in licensed Super Famicom . Released only to Japanese markets, the unit retailed in 1990 as a next generation successor to the 1983 C1 television also produced by Sharp and licensed by Nintendo. Like the C1, the SF1 was noted as having superior picture quality to a SFC plugged into a standard television.
61-630: The SF1 came in two different models varying in screen sizes. The larger SF1 unit featured a 21-inch screen and the smaller featured a 14-inch screen. Both units were colored gray, and both included a ROM-cartridge plugin-slot just above the screen. By merging the SFC and the television into one unit, the SF1 avoided the problem of exposed power cords and other cables. This gave the unit the advantage of being easier to handle. With internally connected SFC-SF1 terminals, luminance and chrominance signals could be separated, and
122-880: A 1 nm -interval dataset of CIE 1931 and CIE 1964 provided by Wyszecki 1982. A CIE publication in 1986 appears also to have a 1 nm dataset, probably using the same data. Like the regular 5 nm dataset, this dataset is also derived from interpolation. The derivation of the CIE standard observer from color matching experiments is given below , after the description of the CIE RGB space. The CIE's color matching functions x ¯ ( λ ) {\displaystyle {\overline {x}}(\lambda )} , y ¯ ( λ ) {\displaystyle {\overline {y}}(\lambda )} and z ¯ ( λ ) {\displaystyle {\overline {z}}(\lambda )} are
183-493: A "standard observer", which attempts to predict the perception of unique hues of color. These color spaces are essential tools that provide the foundation for measuring color for industry, including inks, dyes, and paints, illumination, color imaging, etc. The CIE color spaces contributed to the development of color television, the creation of instruments for maintaining consistent color in manufacturing processes, and other methods of color management . The initials CIE come from
244-457: A color with a spectral radiance L e,Ω,λ are given in terms of the standard observer by: where λ {\displaystyle \lambda } is the wavelength of the equivalent monochromatic light (measured in nanometers ), and customary limits of the integral are λ ∈ [ 380 , 780 ] {\displaystyle \lambda \in [380,780]} . The values of X , Y , and Z are bounded if
305-424: A combination of the three primaries at relative intensities r ¯ ( λ ) {\displaystyle {\bar {r}}(\lambda )} , g ¯ ( λ ) {\displaystyle {\bar {g}}(\lambda )} , and b ¯ ( λ ) {\displaystyle {\bar {b}}(\lambda )} respectively, then
366-488: A one-lobe function. The CIE XYZ color matching functions are nonnegative, and lead to nonnegative XYZ coordinates for all real colors (that is, for nonnegative light spectra). Other observers, such as for the CIE RGB space or other RGB color spaces , are defined by other sets of three color-matching functions, not generally nonnegative, and lead to tristimulus values in those other spaces, which may include negative coordinates for some real colors. The tristimulus values for
427-443: A particular bandwidth. Luma is the weighted sum of gamma-compressed R′G′B′ components of a color video—the prime symbols ′ denote gamma compression . The word was proposed to prevent confusion between luma as implemented in video engineering and relative luminance as used in color science (i.e. as defined by CIE ). Relative luminance is formed as a weighted sum of linear RGB components, not gamma-compressed ones. Even so, luma
488-493: A tabulation of these values at various λ will estimate three functions of wavelength. These are the RGB color-matching functions. Any spectral distribution can be thought of as a combination of a number of monochromatic sources at varying intensities, so that (by Grassmann's laws ) integrating the color matching functions with that spectral distribution will yield the intensities of the three primaries necessary to match it. The problem
549-427: A test color was projected while on the other an observer-adjustable color was projected. The adjustable color was a mixture of the three monochromatic primary colors, each with adjustable brightness. The observer would alter the brightness of each of the three primary beams until a match to the test color was observed. If the test color were simply a monochromatic color at wavelength λ, and if it could be matched by
610-435: A tristimulus specification of the objective color of the light spectrum. The three parameters, denoted "S", "M", and "L", are indicated using a 3-dimensional space denominated the " LMS color space ", which is one of many color spaces devised to quantify human color vision . A color space maps a range of physically produced colors from mixed light, pigments , etc. to an objective description of color sensations registered in
671-404: Is known as the "1931 CIE standard observer". Rather than specify the brightness of each primary, the curves are normalized to have constant area beneath them. This area is fixed to a particular value by specifying that The resulting normalized color matching functions are then scaled in the r:g:b ratio of 1:4.5907:0.0601 for source luminance and 72.0962:1.3791:1 for source radiance to reproduce
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#1732863125174732-458: Is often arbitrarily chosen so that Y = 1 or Y = 100 is the brightest white that a color display supports. In this case, the Y value is known as the relative luminance . The corresponding whitepoint values for X and Z can then be inferred using the standard illuminants . Since the XYZ values are defined much earlier than the characterization of cone cells in the 1950s (by Ragnar Granit ),
793-445: Is recommended when dealing with more than about a 4° field of view. Both standard observer functions are discretized at 5 nm wavelength intervals from 380 nm to 780 nm and distributed by the CIE . All corresponding values have been calculated from experimentally obtained data using interpolation . The standard observer is characterized by three color matching functions . There is also
854-470: Is sometimes erroneously called luminance. SMPTE EG 28 recommends the symbol Y ′ {\displaystyle Y'} to denote luma and the symbol Y {\displaystyle Y} to denote relative luminance. While luma is more often encountered, relative luminance is sometimes used in video engineering when referring to the brightness of a monitor. The formula used to calculate relative luminance uses coefficients based on
915-431: Is that the three primaries can only produce colors which lie withinin their gamut - the triangle in color space formed by the primaries, which never touches the monochromatic locus nor the purple line except at the three primaries. In other words, there is no monochromatic source that can be matched by a combination of the three primaries, except at the wavelengths of the three primaries themselves. However, by adding one of
976-430: Is the wavelength of the equivalent monochromatic light (measured in nanometers ), and the standard limits of the integral are λ ∈ [ 380 , 780 ] {\displaystyle \lambda \in [380,780]} . Since the human eye has three types of color sensors that respond to different ranges of wavelengths , a full plot of all visible colors is a three-dimensional figure. However,
1037-516: The CIE color matching functions and the relevant standard chromaticities of red, green, and blue (e.g., the original NTSC primaries, SMPTE C , or Rec. 709 ). For the Rec. 709 (and sRGB ) primaries, the linear combination, based on pure colorimetric considerations and the definition of relative luminance is: The formula used to calculate luma in the Rec. 709 spec arbitrarily also uses these same coefficients, but with gamma-compressed components: where
1098-451: The LMS color space , but not restricted to non-negative sensitivities, associates physically produced light spectra with specific tristimulus values. Consider two light sources composed of different mixtures of various wavelengths. Such light sources may appear to be the same color; this effect is called " metamerism ." Such light sources have the same apparent color to an observer when they produce
1159-453: The RGB color spaces , imply negative values for at least one of the three primaries because the chromaticity would be outside the color triangle defined by the primary colors. To avoid these negative RGB values, and to have one component that describes the perceived brightness , "imaginary" primary colors and corresponding color-matching functions were formulated. The CIE 1931 color space defines
1220-689: The SMPTE 240M coefficients: These coefficients correspond to the SMPTE RP 145 primaries (also known as "SMPTE C") in use at the time the standard was created. The change in the luma coefficients is to provide the "theoretically correct" coefficients that reflect the corresponding standard chromaticities ('colors') of the primaries red, green, and blue. However, there is some controversy regarding this decision. The difference in luma coefficients requires that component signals must be converted between Rec. 601 and Rec. 709 to provide accurate colors. In consumer equipment,
1281-498: The SMPTE color bars test pattern. Error in luminance can be seen as a dark band that occurs in this area. Color matching function In 1931 the International Commission on Illumination (CIE) published the CIE 1931 color spaces which define the relationship between the visible spectrum and the visual sensation of specific colors by human color vision . The CIE color spaces are mathematical models that create
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#17328631251741342-418: The Y tristimulus value: The figure on the right shows the related chromaticity diagram. The outer curved boundary is the spectral locus , with wavelengths shown in nanometers. The chromaticity diagram is a tool to specify how the human eye will experience light with a given spectrum. It cannot specify colors of objects (or printing inks), since the chromaticity observed while looking at an object depends on
1403-439: The luminance of a color. The chromaticity is then specified by the two derived parameters x and y , two of the three normalized values being functions of all three tristimulus values X , Y , and Z : That is, because each tristimulus parameter, X , Y , Z , is divided by the sum of all three, the resulting values, x , y , z , each represent a proportion of the whole and so their sum must be equal to one. Therefore,
1464-415: The 1920s, two independent experiments on human color perception were conducted by W. David Wright with ten observers, and John Guild with seven observers. Their results laid the foundation for the trichromatic CIE XYZ color space specification. The experiments were conducted by using a circular split screen (a bipartite field) 2 degrees in diameter, which is the angular size of the human fovea. On one side
1525-515: The CIE 1931 model, Y is the luminance , Z is quasi-equal to blue (of CIE RGB), and X is a mix of the three CIE RGB curves chosen to be nonnegative (see § Definition of the CIE XYZ color space ). Setting Y as luminance has the useful result that for any given Y value, the XZ plane will contain all possible chromaticities at that luminance. The unit of the tristimulus values X , Y , and Z
1586-848: The CIE RGB color space. The CIE XYZ color space was derived from CIE RGB in an effort to simplify the math. The CIE 1931 XYZ color space is still widely used, even though it is not perceptually uniform in relation to human vision. In 1976 the CIE published the CIELUV and CIELAB color spaces, which are derived from XYZ, and are intended to provide more uniform predictions relative to human perception. The human eye with normal vision has three kinds of cone cells that sense light, having peaks of spectral sensitivity in short ("S", 420 nm – 440 nm ), medium ("M", 530 nm – 540 nm ), and long ("L", 560 nm – 580 nm ) wavelengths. These cone cells underlie human color perception in conditions of medium and high brightness; in very dim light color vision diminishes, and
1647-501: The CIE XYZ color matching functions can be approximated by a sum of Gaussian functions , as follows: Let g ( x ) denote a piecewise-Gaussian function, defined by That is, g ( x ) resembles a bell curve with its peak at x = μ , a spread/standard deviation of 1 / τ 1 {\displaystyle 1/\tau _{1}} to the left of the mean, and spread of 1 / τ 2 {\displaystyle 1/\tau _{2}} to
1708-617: The French name "Commission Internationale de l'éclairage" , which has maintained and developed many of the standards in use today relating to colorimetry . The CIE color spaces were created using data from a series of experiments, where human test subjects adjusted red, green, and blue primary colors to find a visual match to a second, pure color. The original experiments were conducted in the mid 1920s by William David Wright [ ja ] using ten observers and John Guild using seven observers. The experimental results were combined, creating
1769-448: The LMS cone responses of the human eye. Due to the distribution of cones in the eye, the tristimulus values depend on the observer's field of view . To eliminate this variable, the CIE defined a color-mapping function called the standard (colorimetric) observer , to represent an average human's chromatic response within a 2° arc inside the fovea . This angle was chosen owing to the belief that
1830-925: The amounts of primaries needed to match the monochromatic test primary. These functions are shown in the plot on the right (CIE 1931). r ¯ ( λ ) {\displaystyle {\overline {r}}(\lambda )} and g ¯ ( λ ) {\displaystyle {\overline {g}}(\lambda )} are zero at 435.8 nm , r ¯ ( λ ) {\displaystyle {\overline {r}}(\lambda )} and b ¯ ( λ ) {\displaystyle {\overline {b}}(\lambda )} are zero at 546.1 nm and g ¯ ( λ ) {\displaystyle {\overline {g}}(\lambda )} and b ¯ ( λ ) {\displaystyle {\overline {b}}(\lambda )} are zero at 700 nm , since in these cases
1891-546: The back of the "console" portion of the set, and a cover could be applied to prevent dust. Doubts over the awkward attachment of expansion peripherals were among the reasons the unit never ultimately saw an international release. Despite the graphical superiority and general future-proofing, the SF1 only supports mono audio. Only two models were released in Japan. Luminance (video) In video , luma ( Y ′ {\displaystyle Y'} ) represents
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1952-604: The brightness in an image (the "black-and-white" or achromatic portion of the image). Luma is typically paired with chrominance . Luma represents the achromatic image, while the chroma components represent the color information. Converting R′G′B′ sources (such as the output of a three-CCD camera ) into luma and chroma allows for chroma subsampling : because human vision has finer spatial sensitivity to luminance ("black and white") differences than chromatic differences, video systems can store and transmit chromatic information at lower resolution, optimizing perceived detail at
2013-454: The color-sensitive cones resided within a 2° arc of the fovea. Thus the CIE 1931 Standard Observer function is also known as the CIE 1931 2° Standard Observer . A more modern but less-used alternative is the CIE 1964 10° Standard Observer , which is derived from the work of Stiles and Burch, and Speranskaya. For the 10° experiments, the observers were instructed to ignore the central 2° spot. The 1964 Supplementary Standard Observer function
2074-408: The concept of color can be divided into two parts: brightness and chromaticity . For example, the color white is a bright color, while the color grey is considered to be a less bright version of that same white. In other words, the chromaticity of white and grey are the same while their brightness differs. The CIE XYZ color space was deliberately designed so that the Y parameter is also a measure of
2135-643: The earlier Sharp Nintendo Television, AV output terminals were made readily accessible on the SF1's extended terminal which allowed connection to later peripherals such as the Satellaview . The C1 had been notably unable to connect to the Family Computer Disk System , and the SF1's design was intended to alleviate this problem with any Super Famicom peripherals. To use the extended terminal, the Satellaview's AV output terminal would attach obliquely upward on
2196-857: The green and blue matching functions have rather small negative values. Although Wright and Guild's experiments were carried out using various primaries at various intensities, and although they used a number of different observers, all of their results were summarized by the standardized CIE RGB color matching functions r ¯ ( λ ) {\displaystyle {\overline {r}}(\lambda )} , g ¯ ( λ ) {\displaystyle {\overline {g}}(\lambda )} , and b ¯ ( λ ) {\displaystyle {\overline {b}}(\lambda )} , obtained using three monochromatic primaries at standardized wavelengths of 700 nm (red), 546.1 nm (green) and 435.8 nm (blue). The (un-normalized) color matching functions are
2257-463: The green and red primaries, some blue must be added and b ¯ ( λ ) {\displaystyle {\bar {b}}(\lambda )} will be negative. For wavelengths below the wavelength of the blue primary, or above the wavelength of the red primary, some green must be added and g ¯ ( λ ) {\displaystyle {\bar {g}}(\lambda )} will be negative. In each case,
2318-419: The human eye, typically in terms of tristimulus values, but not usually in the LMS color space defined by the spectral sensitivities of the cone cells . The tristimulus values associated with a color space can be conceptualized as amounts of three primary colors in a tri-chromatic, additive color model . In some color spaces, including the LMS and XYZ spaces, the primary colors used are not real colors in
2379-404: The light source as well. Mathematically the colors of the chromaticity diagram occupy a region of the real projective plane . The chromaticity diagram illustrates a number of interesting properties of the CIE XYZ color space: When two or more colors are additively mixed, the x and y chromaticity coordinates of the resulting color (x mix ,y mix ) may be calculated from the chromaticities of
2440-432: The low-brightness, monochromatic "night vision" receptors, denominated " rod cells ", become effective. Thus, three parameters corresponding to levels of stimulus of the three kinds of cone cells, in principle describe any human color sensation. Weighting a total light power spectrum by the individual spectral sensitivities of the three kinds of cone cells renders three effective values of stimulus ; these three values compose
2501-421: The luminance of an image. Note the bleeding in lightness near the borders. Due to the widespread usage of chroma subsampling , errors in chroma typically occur when it is lowered in resolution/bandwidth. This lowered bandwidth, coupled with high frequency chroma components, can cause visible errors in luminance. An example of a high frequency chroma component would be the line between the green and magenta bars of
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2562-421: The luminance values (L 1 , L 2 , etc.) one can alternatively use any other photometric quantity that is directly proportional to the tristimulus value Y (naturally meaning that Y itself can also be used as well). As already mentioned, when two colors are mixed, the resulting color x mix , y mix will lie on the straight line segment that connects these colors on the CIE xy chromaticity diagram. To calculate
2623-522: The matrix required to perform this conversion may be omitted (to reduce cost), resulting in inaccurate color. As well, the Rec. 709 luma coefficients may not necessarily provide better performance. Because of the difference between luma and relative luminance, luma does not exactly represent the luminance in an image. As a result, errors in chroma can affect luminance. Luma alone does not perfectly represent luminance; accurate luminance requires both accurate luma and chroma. Hence, errors in chroma "bleed" into
2684-403: The mixing ratio of the component colors x 1 ,y 1 and x 2 ,y 2 that results in a certain x mix ,y mix on this line segment, one can use the formula where L 1 is the luminance of color x 1 ,y 1 and L 2 the luminance of color x 2 ,y 2 . Because y mix is unambiguously determined by x mix and vice versa, knowing just one or the other of them is enough for calculating
2745-464: The mixing ratio. In accordance with the remarks concerning the formulas for x mix and y mix , the mixing ratio L 1 /L 2 may well be expressed in terms of other photometric quantities than luminance. The first step in developing the CIE XYZ color space is the measurement of the CIE RGB color space. The CIE RGB color space is one of many RGB color spaces , distinguished by a particular set of monochromatic (single-wavelength) primary colors . In
2806-418: The mixture components (x 1 ,y 1 ; x 2 ,y 2 ; …; x n ,y n ) and their corresponding luminances (L 1 , L 2 , …, L n ) with the following formulas: These formulas can be derived from the previously presented definitions of x and y chromaticity coordinates by taking advantage of the fact that the tristimulus values X, Y, and Z of the individual mixture components are directly additive. In place of
2867-418: The numerical description of the chromatic response of the observer (described above). They can be thought of as the spectral sensitivity curves of three linear light detectors yielding the CIE tristimulus values X , Y and Z . Collectively, these three functions describe the CIE standard observer. Table lookup can become impractical for some computational tasks. Instead of referring to the published table,
2928-421: The physiological meaning of these values are known only much later. The Hunt-Pointer-Estevez matrix from the 1980s relates XYZ with LMS. When inverted, it shows how the three cone responses add up to XYZ functions: In other words, the Z value is solely made up of the S cone response, the Y value a mix of L and M responses, and X value a mix of all three. This fact makes XYZ values analogous to, but different from,
2989-624: The primaries to the monochromatic test color, the test color can be brought into the RGB gamut, allowing a match to be made. Adding a primary to the monochromatic test color is effectively the same as subtracting it from the adjustable color, which of course cannot be done since it is impossible to have a negative intensity for any of the primaries. For wavelengths between the blue and green primaries, some red primary must be added to allow matching, resulting in negative values of r ¯ ( λ ) {\displaystyle {\bar {r}}(\lambda )} . Likewise, between
3050-408: The prime symbol ′ denotes gamma compression . For digital formats following CCIR 601 (i.e. most digital standard definition formats), luma is calculated with this formula: Formats following ITU-R Recommendation BT. 709 (i.e. most digital high definition formats) use a different formula: Modern HDTV systems use the 709 coefficients, while transitional 1035i HDTV (MUSE) formats may use
3111-468: The radiance spectrum L e,Ω,λ is bounded. The reflective and transmissive cases are very similar to the emissive case, with a few differences. The spectral radiance L e,Ω,λ is replaced by the spectral reflectance (or transmittance ) S(λ) of the object being measured, multiplied by the spectral power distribution of the illuminant I(λ) . where K is a scaling factor (usually 1 or 100), and λ {\displaystyle \lambda }
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#17328631251743172-452: The remaining two color matching functions will be positive. It can be seen that the deviation of the RGB gamut from the complete gamut is rather small except between the blue and green primaries at 435.8 and 546.1 nm. In this wavelength band, rather large amounts of the red primary needed to be added to the test color, and it is in this band that the red color matching function has rather large negative values. In their regions of negative values,
3233-445: The resulting image quality was notably sharper than standard setups. This advantage diminished to a degree in the 14-inch model where picture quality was reduced. Additional functions were added to the remote control such that the SFC portion of the unit can be reset by simultaneously pressing two buttons. Additionally, the remote control could be used to record gameplay on the VCR. Unlike
3294-438: The resulting tristimulus values, in which they are denoted by "X", "Y", and "Z". In XYZ space, all combinations of non-negative coordinates are meaningful, but many, such as the primary locations [1, 0, 0], [0, 1, 0], and [0, 0, 1], correspond to imaginary colors outside the space of possible LMS coordinates; imaginary colors do not correspond to any spectral distribution of wavelengths and therefore have no physical reality. In
3355-435: The results. The color matching functions and primaries were settled upon by a CIE special commission after considerable deliberation. The cut-offs at the short- and long-wavelength side of the diagram are chosen somewhat arbitrarily; the human eye can actually see light with wavelengths up to about 810 nm , but with a sensitivity that is many thousand times lower than for green light. These color matching functions define what
3416-473: The right of the mean. With the wavelength λ measured in nanometers , we then approximate the 1931 color matching functions: The squared differences between the above approximation and the measured CIE xyz color matching functions is less than the within-observer variance encountered in the experimental measurements used to form the CIE standards. It is also possible to use fewer gaussian functions, with one gaussian for each "lobe". CIE 1964 fits well with
3477-490: The same tristimulus values, regardless of the spectral power distributions of the sources. Most wavelengths stimulate two or all three kinds of cone cell because the spectral sensitivity curves of the three kinds overlap. Certain tristimulus values are thus physically impossible: e.g. LMS tristimulus values that are non-zero for the M component and zero for both the L and S components. Furthermore pure spectral colors would, in any normal trichromatic additive color space, e.g.,
3538-421: The sense that they cannot be generated in any light spectrum. The CIE XYZ color space encompasses all color sensations that are visible to a person with average eyesight. That is why CIE XYZ tristimulus values are a device-invariant representation of color. It serves as a standard reference against which many other color spaces are defined. A set of color-matching functions, like the spectral sensitivity curves of
3599-461: The test color is one of the primaries. The primaries with wavelengths 546.1 nm and 435.8 nm were chosen because they are easily reproducible monochromatic lines of a mercury vapor discharge. The 700 nm wavelength, which in 1931 was difficult to reproduce as a monochromatic beam, was chosen because the eye's perception of color is rather unchanging at this wavelength, and therefore small errors in wavelength of this primary would have little effect on
3660-442: The true color matching functions. By proposing that the primaries be standardized, the CIE established an international system of objective color notation. Given these scaled color matching functions, the RGB tristimulus values for a color with a spectral power distribution S ( λ ) {\displaystyle S(\lambda )} would then be given by: These are all inner products and can be thought of as
3721-400: The value z can be deduced by knowing x and y , and consequently the latter two values are sufficient for describing the chromaticity of any color. The derived color space specified by x , y , and Y is known as the CIE xyY color space and is widely used to specify colors in practice. The X and Z tristimulus values can be calculated back from the chromaticity values x and y and
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