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PVRTC
PVRTC (PowerVR Texture Compression) and PVRTC2 are a family of lossy, fixed-rate texture compression formats used in PowerVR's MBX (PVRTC only), SGX and Rogue technologies. The PVRTC algorithm is documented in Simon Fenney's paperTexture Compression using Low-Frequency Signal Modulation that was presented aGraphics Hardware 2003 These differ from block-based texture formats such as S3TC and Ericsson Texture Compression (ETC) in that the compressed image is represented by two lower resolution images which are bilinearly upscaled and then blended according to low precision, per-pixel weights. They also differ in that they support ARGB data in both 4-bpp and 2-bpp modes. PVRTC is the compressed texture format used in the Nokia N9 and all generations of the iPhone, iPod Touch, and iPad. It is also supported in certain Android devices, that use PowerVR GPUs. Data structure In both PVRTC and PVRTC2, texture data is stored in blocks (but note that the decoding of any 2x2 set of texels re ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Texture Compression
Texture compression is a specialized form of image compression designed for storing texture maps in 3D computer graphics rendering systems. Unlike conventional image compression algorithms, texture compression algorithms are optimized for random access. Tradeoffs In their seminal paper on texture compression, Beers, Agrawala and Chaddha list four features that tend to differentiate texture compression from other image compression techniques. These features are: ;Decoding Speed: It is highly desirable to be able to render directly from the compressed texture data and so, in order not to impact rendering performance, decompression must be fast. ;Random Access: Since predicting the order that a renderer accesses texels would be difficult, any texture compression scheme must allow fast random access to decompressed texture data. This tends to rule out many better-known image compression schemes such as JPEG or run-length encoding. ;Compression Rate and Visual Quality: In a rendering ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
S3TC
S3 Texture Compression (S3TC) (sometimes also called DXTn, DXTC, or BCn) is a group of related lossy texture compression algorithms originally developed by Iourcha et al. of S3 Graphics, Ltd. for use in their Savage 3D computer graphics accelerator. The method of compression is strikingly similar to the previously published Color Cell Compression, which is in turn an adaptation of Block Truncation Coding published in the late 1970s. Unlike some image compression algorithms (e.g. JPEG), S3TC's fixed-rate data compression coupled with the single memory access (cf. Color Cell Compression and some VQ-based schemes) made it well-suited for use in compressing textures in hardware-accelerated 3D computer graphics. Its subsequent inclusion in Microsoft's DirectX 6.0 and OpenGL 1.3 (via the GL_EXT_texture_compression_s3tc extension) led to widespread adoption of the technology among hardware and software makers. While S3 Graphics is no longer a competitor in the graphics accelerator market ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Texture Compression
Texture compression is a specialized form of image compression designed for storing texture maps in 3D computer graphics rendering systems. Unlike conventional image compression algorithms, texture compression algorithms are optimized for random access. Tradeoffs In their seminal paper on texture compression, Beers, Agrawala and Chaddha list four features that tend to differentiate texture compression from other image compression techniques. These features are: ;Decoding Speed: It is highly desirable to be able to render directly from the compressed texture data and so, in order not to impact rendering performance, decompression must be fast. ;Random Access: Since predicting the order that a renderer accesses texels would be difficult, any texture compression scheme must allow fast random access to decompressed texture data. This tends to rule out many better-known image compression schemes such as JPEG or run-length encoding. ;Compression Rate and Visual Quality: In a rendering ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
PowerVR
PowerVR is a division of Imagination Technologies (formerly VideoLogic) that develops hardware and software for 2D and 3D rendering, and for video encoding, decoding, associated image processing and DirectX, OpenGL ES, OpenVG, and OpenCL acceleration. PowerVR also develops AI accelerators called Neural Network Accelerator (NNA). The PowerVR product line was originally introduced to compete in the desktop PC market for 3D hardware accelerators with a product with a better price–performance ratio than existing products like those from 3dfx Interactive. Rapid changes in that market, notably with the introduction of OpenGL and Direct3D, led to rapid consolidation. PowerVR introduced new versions with low-power electronics that were aimed at the laptop computer market. Over time, this developed into a series of designs that could be incorporated into system-on-a-chip architectures suitable for handheld device use. PowerVR accelerators are not manufactured by PowerVR, but instead t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ericsson Texture Compression
Ericsson Texture Compression (ETC) is a lossy texture compression technique developed in collaboration with Ericsson Research in early 2005. It was originally developed under the name iPACKMAN and based on an earlier compression scheme called PACKMAN. ETC1 The original 'ETC1' compression scheme provides 6x compression of 24-bit RGB data. It does not support the compression of images with Alpha components, although there are work-arounds for this. ETC1 takes 4x4 groups of pixel data and compresses each into a single 64-bit word. The 4×4 pixel group is first divided into two 4×2 chunks - either horizontally or vertically. Each half is given a base color - either using 4/4/4 RGB or by giving one of them a 5/5/5 RGB and having the other be a 3/3/3 bit offset from that base. Each 4×2 region also has a 3-bit brightness range selection. Each pixel is then offset from the base color by adding one of four signed values to the base color for its half of the 4×4 group. This format ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ARGB
RGBA stands for red green blue alpha. While it is sometimes described as a color space, it is actually a three-channel RGB color model supplemented with a fourth ''alpha channel''. Alpha indicates how opaque each pixel is and allows an image to be combined over others using alpha compositing, with transparent areas and anti-aliasing of the edges of opaque regions. The term does ''not'' define what RGB color space is being used. It also does not state whether or not the colors are premultiplied by the alpha value, and if they are it does not state what color space that premultiplication was done in. This means more information than just "RGBA" is needed to determine how to handle an image. In some contexts the abbreviation "RGBA" means a specific memory layout (called RGBA8888 below), with other terms such as "BGRA" used for alternatives. In other contexts "RGBA" means any layout. Representation In computer graphics, pixels encoding the RGBA color space information must be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nokia N9
The Nokia N9 (codename '' Lankku'') is a flagship smartphone developed by Nokia, running on the Linux-based MeeGo mobile operating system. Announced in June 2011 and released in September, it was the first and only device from Nokia with MeeGo, partly because of the company's partnership with Microsoft announced that year. It was initially released in three colors: black, cyan and magenta, before a white version was announced at Nokia World 2011. Despite a limited release, the N9 received widespread critical acclaim, with some describing it as Nokia's finest device to date. It was praised for both its software and hardware, including the MeeGo operating system, buttonless 'swipe' user interface, and its high-end features. The case would be reused for the Windows Phone-powered Nokia Lumia 800 which was released later that year. Background The successor of Nokia N900, internally known as N9-00, was scheduled to be released in late 2010, approximately one year after N900 launche ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IPod Touch
The iPod Touch (stylized as iPod touch) is a discontinued line of iOS-based mobile devices designed and marketed by Apple Inc. with a touchscreen-controlled user interface. As with other iPod models, the iPod Touch can be used as a music player and a handheld gaming device, but can also be used as a digital camera, a web browser and for messaging. It is similar in design to the iPhone, but it connects to the Internet only through Wi-Fi and does not use cellular network data, so it is not a smartphone. The iPod Touch was introduced in 2007; some 100 million iPod Touch units were sold by May 2013. The final generation of iPod Touch, released on May 28, 2019, is the seventh-generation model. iPod Touch models were sold by storage space and color; all models of the same generation typically offered identical features, performance, and operating system upgrades. An exception was the fifth generation, in which the low-end (16 GB) model was initially sold without a rea ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
IPad
The iPad is a brand of iOS and iPadOS-based tablet computers that are developed by Apple Inc. The iPad was conceived before the related iPhone but the iPhone was developed and released first. Speculation about the development, operating system, and release of the original iPad began in 2002 prior to its introduction on January 20, 2010. The iPad range consists of the original iPad lineup and the flagship products iPad Mini, iPad Air, and iPad Pro. The iPhone's iOS operating system (OS) was initially used for the iPad but in September 2019, its OS was switched to a fork of iOS called iPadOS that has better support for the device's hardware and its user interface is customized for the tablets' larger screens. The iPad's App Store is subject to application and content approval. Many older devices are susceptible to jailbreaking, which circumvents these restrictions. The original iPad was well-received for its software and was recognized as one of the most-influential inven ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Morton Order
In mathematical analysis and computer science, functions which are Z-order, Lebesgue curve, Morton space-filling curve, Morton order or Morton code map multidimensional data to one dimension while preserving locality of the data points. It is named in France after Henri Lebesgue, who studied it in 1904, and named in US after Guy Macdonald Morton, who first applied the order to file sequencing in 1966. The z-value of a point in multidimensions is simply calculated by interleaving the binary representations of its coordinate values. Once the data are sorted into this ordering, any one-dimensional data structure can be used such as binary search trees, B-trees, skip lists or (with low significant bits truncated) hash tables. The resulting ordering can equivalently be described as the order one would get from a depth-first traversal of a quadtree or octree. Coordinate values The figure below shows the Z-values for the two dimensional case with integer coordinates 0 ≤&nb ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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