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YJK
YJK is a proprietary color space implemented by the Yamaha V9958 graphic chip on MSX2+ computers. It has the advantage of encoding images by implementing less resolution for color information than for brightness, taking advantage of the human visual systems' lower acuity for color differences. This saves memory, transmission and computing power. YJK is composed of three components: Y, J and K. Y is similar to luminance (but computed differently), J and K are the chrominance components (representing the red and green color differences). The Y component is a 5-bit value (0 to 31), specified for each individual pixel. The J and K components are stored together in 6 bits (-32 to 31) and shared between 4 nearby pixels (4:2:0 chroma sub-sampling). While conceptually similar to YUV, chroma sampling, numerical relationship between the components, and transformation to and from RGB are different in YJK. Formulas The three component signals are created from an original RGB (red, gre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
YJK Example Image
YJK is a proprietary color space implemented by the Yamaha V9958 graphic chip on MSX2+ computers. It has the advantage of encoding images by implementing less resolution for color information than for brightness, taking advantage of the human visual systems' lower acuity for color differences. This saves memory, transmission and computing power. YJK is composed of three components: Y, J and K. Y is similar to luminance (but computed differently), J and K are the chrominance components (representing the red and green color differences). The Y component is a 5-bit value (0 to 31), specified for each individual pixel. The J and K components are stored together in 6 bits (-32 to 31) and shared between 4 nearby pixels (4:2:0 chroma sub-sampling). While conceptually similar to YUV, chroma sampling, numerical relationship between the components, and transformation to and from RGB are different in YJK. Formulas The three component signals are created from an original RGB (red, gre ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yamaha V9958
The Yamaha V9958 is a Video Display Processor used in the MSX2+ and MSX turbo R series of home computers, as the successor to the Yamaha V9938 used in the MSX2. The main new features are three graphical YJK modes with up to 19268 colors and horizontal scrolling registers. The V9958 was not as widely adopted as the V9938. Specifications * Video RAM: 128 KB + 64 KB of expanded VRAM * Text modes: 80 x 24 and 32 x 24 * Resolution: 512 x 212 (4 or 16 colors out of 512) and 256 x 212 (16, 256, 12499 or 19268 colors) * Sprites: 32, 16 colors, max 8 per horizontal line * Hardware acceleration for copy, line, fill, etc. * Interlacing to double vertical resolution * Horizontal and vertical scroll registers Feature changes from the V9938 The following features were added to or removed from the Yamaha V9938 specifications: * Added horizontal scrolling registers * Added YJK graphics modes (similar to YUV): ** G7 + YJK + YAE: 256 x 212, 12499 colors + 16 color palette ** G7 + YJK: 256 x 21 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chroma Sampling
Chroma subsampling is the practice of encoding images by implementing less resolution for chroma information than for luma information, taking advantage of the human visual system's lower acuity for color differences than for luminance. It is used in many video and still image encoding schemesboth analog and digitalincluding in JPEG encoding. Rationale Digital signals are often compressed to reduce file size and save transmission time. Since the human visual system is much more sensitive to variations in brightness than color, a video system can be optimized by devoting more bandwidth to the luma component (usually denoted Y'), than to the color difference components Cb and Cr. In compressed images, for example, the 4:2:2 Y'CbCr scheme requires two-thirds the bandwidth of non-subsampled "4:4:4" R'G'B'. This reduction results in almost no visual difference as perceived by the viewer. How subsampling works At normal viewing distances, there is no perceptible loss incurred by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MSX2+
MSX is a standardized home computer architecture, announced by Microsoft and ASCII Corporation on June 16, 1983. It was initially conceived by Microsoft as a product for the Eastern sector, and jointly marketed by Kazuhiko Nishi, then vice-president at Microsoft and director at ASCII Corporation. Microsoft and Nishi conceived the project as an attempt to create unified standards among various home computing system manufacturers of the period, in the same fashion as the VHS standard for home video tape machines. MSX systems were popular in Japan and several other countries. Eventually, 9 million MSX units were sold worldwide, including in Japan alone. Despite Microsoft's involvement, few MSX-based machines were released in the United States. The very first commercial MSX for the public was a Mitsubishi ML-8000, released on October 21, 1983, thus marking its official "release date". The meaning of the acronym MSX remains a matter of debate. In 2001, Kazuhiko Nishi recalled t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rgb Vs YJK
The RGB color model is an additive color model in which the red, green and blue primary colors of light are added together in various ways to reproduce a broad array of colors. The name of the model comes from the initials of the three additive primary colors, red, green, and blue. The main purpose of the RGB color model is for the sensing, representation, and display of images in electronic systems, such as televisions and computers, though it has also been used in conventional photography. Before the electronic age, the RGB color model already had a solid theory behind it, based in human perception of colors. RGB is a ''device-dependent'' color model: different devices detect or reproduce a given RGB value differently, since the color elements (such as phosphors or dyes) and their response to the individual red, green, and blue levels vary from manufacturer to manufacturer, or even in the same device over time. Thus an RGB value does not define the same ''color'' across dev ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
