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The main use of pngcrush is for reducing the size of the image data contained in the IDAT section. The pixel data in a PNG file is compressed using LZ77 algorithm (which tries to find repeated byte sequences in the source data), and then further compressed with Huffman algorithm. This combination is referred to as deflate compression. Before ...
Bathymetric Attributed Grid (BAG) is a file format designed to store and exchange bathymetric data.. The implementation of the format was triggered by the large adoption of gridded bathymetry and the need of transferring the required information about bathymetry and associated uncertainty (i.e., metadata) between processing applications.
This characteristic sometimes results in a smaller file size for some lossless formats than lossy formats. For example, graphically simple images (i.e. images with large continuous regions like line art or animation sequences) may be losslessly compressed into a GIF or PNG format and result in a smaller file size than a lossy JPEG format.
In fact, if we consider files of length N, if all files were equally probable, then for any lossless compression that reduces the size of some file, the expected length of a compressed file (averaged over all possible files of length N) must necessarily be greater than N. [citation needed] So if we know nothing about the properties of the data ...
Image compression is a type of data compression applied to digital images, to reduce their cost for storage or transmission. Algorithms may take advantage of visual perception and the statistical properties of image data to provide superior results compared with generic data compression methods which are used for other digital data.
Group 4 compression is available in many proprietary image file formats as well as standardized formats such as TIFF, CALS, CIT (Intergraph Raster Type 24) and the PDF document format. G4 offers a small improvement over G3-2D by removing the end-of-line (EOL) codes. G3 and G4 compression both treat an image as a series of horizontal black ...
In addition, transparency is often an "extra" for a graphics format, and some graphics programs will ignore the transparency. Animated PNG 8-bit transparency. Raster file formats that support transparency include GIF, PNG, BMP, TIFF, TGA and JPEG 2000, through either a transparent color or an alpha channel.
A grid-based spatial index has the advantage that the structure of the index can be created first, and data added on an ongoing basis without requiring any change to the index structure; indeed, if a common grid is used by disparate data collecting and indexing activities, such indices can easily be merged from a variety of sources.