bytore.blogg.se - Which are used to create a raster image

For workstationĪpplications where a complete but relatively small image is first Such as JPEG 2000, are compute-intensive to decompress.

Amount of processing power required to decompress the imageĬompression requires that the system decompress the imageryīefore any processing can be applied.

LERC compression is a veryĮfficient lossless or controlled lossy compression that minimizes the compute load. JPEG compression are supported in ArcGIS. SomeĬompression algorithms are much more compute-efficient than others.įormat due to it speed and the good compression ratio achieved. Compressing imageryĪlso increases the compute load for reading the imagery. Reduce data volumes, but may add unacceptable artifacts to imagery,Įspecially if it is to be used for analysis. Lossy compression algorithms can substantially Of NoData values, but generally provide minimal compression of Lossless compression algorithms, such as LZW/Deflate, can beĮffectively used to compress imagery that contains a large number SuchĬompression substantially reduces the volume of data read from diskĪnd can have a positive influence on performance, especially on Typically, a natural color image can be compressedĥ-10 times with negligible difference in image quality. Volume of data read can also be significantly reduced by usingĬompression. Minimize the volume of imagery that is read, including internal caching and limiting the If the data volume to be read is reduced, thisĬan improve performance. Imagery is tiled, then it is necessary to also maintain an index toįor any group of pixels to be processed, those pixels must be Most modern file formats areĮither tiled or include options for tiling. This makes it faster to access a group of pixels Internally into smaller tiles (typically 256x256 or 512x512 With larger files (more than 3,000 columns), the read access canīe enhanced by using a tiled image format that breaks the image Substantially more than just the section of the raster Store any part of the rows, so the amount of data read is Due to the way storage is managed as blocks onĭisk, it is still necessary for the system to read the blocks that System determines the location on disk for the first part of thatĮxtent, skips to that part and start reading only the appropriate When an extent of an image needs to be read, the The following six factors have the greatest influence on the suitability of a file format:Ī raster may be stored as a simple, non-compressed array of The performance of the storage system as well as theįormat of the imagery can have a significant effect on the

Large images, ArcGIS reads on demand only the required imagery from To enable scalability for large numbers of Many traditional image workstation applications first read the complete image into memory and thenĪllow a user to make changes to the image before saving it. When a new imagery or raster product is created or persisted from another data source (such as a digital terrain model generated from stereo imagery) then the projection, pixel alignment, pixel depth, format and compression should be carefully chosen to ensure appropriate dynamic range, precision, and fast access. Including lossy or losslessĬompression in the format conversion is optional. The imagery, but it does result in data duplication. In some cases, it is advisable to change the format of the Necessary) to ensure that the pixel values do not change. High-quality interpretation, it is preferable (and sometimes Quality, possible artifacts, creation of NoData areas, and issues

When imagery is processed so that the pixels are sampled (forĮxample, to change the projection), this leads to degradation in However, both programs can be used for either purpose depending on your needs.Generally, it is best to leave imagery in its original form. In general, Photoshop is better for editing raster images and Illustrator is better for creating and editing vector graphics. But if you’re working with illustrations or other types of vector graphics, then you’ll probably want to use Illustrator instead. If you’re working with photos or other types of raster images, then Photoshop is the best choice. Vector graphics can be created in Photoshop, but they may not look as smooth as they would if they were created in a vector graphic program such as Adobe Illustrator.Īs we mentioned before, it depends on what you’re trying to do. This is because Photoshop has more tools for manipulating pixels, such as the clone stamp tool and the healing brush tool. Photoshop can create both types of graphics, but it is better suited for raster graphics.

Vector graphics are made up of paths, which are lines that can be any length or width. Raster graphics are made up of pixels, which are small dots of color. Photoshop can be used for both raster and vector graphics, but there are some key differences between the two. This is a common question and the answer is not always simple.