Image Pyramids: Difference between revisions
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The XMS packages include an option to generate multiple resolution versions of an image when it is imported. This can improve the display quality of an image when the native resolution is much higher than the screen resolution. In essence, if the image resolution is larger than the screen resolution, a the display of the image skips pixels so the image appears discontinuous. | |||
There are a few points to keep in mind when building pyramids. The initial generation of pyramid files can take several minutes, depending on the size of the original image and the computer hardware. Building pyramids uses more memory RAM | The process of generating multiple versions of the image is referred to as ''Image Pyramids''. If the feature is invoked, XMS will average 2x2 blocks of pixels in the image creating an approximate version of the image at half the resolution. This process is repeated on the smaller image creating an image at one fourth the original resolution, and so on. Up to four images are generated, based on the relative native resolution and the screen resolution. The goal is to get an image in the ''pyramid'' that is approximately the same as screen resolution. | ||
When displaying all or part of an image, XMS determines which of the ''pyramid'' images have a resolution that most closely matches the current screen pixel size and uses that version of the image. | |||
There are a few points to keep in mind when building pyramids. The initial generation of pyramid files can take several minutes, depending on the size of the original image and the computer hardware. Building pyramids uses more memory RAM. Building pyramids may not improve the on screen display of all images. | |||
Once an image pyramid has been built for a particular image file, the user will not be asked again to build pyramids for that image file unless the image is moved or altered. | Once an image pyramid has been built for a particular image file, the user will not be asked again to build pyramids for that image file unless the image is moved or altered. | ||
When pyramids are built for an image, up to four JPEG images are saved to disk. These image files can be saved to a temporary folder or can be saved in the same directory as the original image so that they are not regenerated each time the image is loaded. | |||
When pyramids are built for an image, up to four JPEG images are saved to disk. These image files can be saved to a temporary folder or can be saved in the same directory as the original image so that they are not regenerated each time the image is loaded. | |||
==Image Preferences== | |||
For XMS versions released after summer 2015, the default option is to not generate image pyramids and not even ask the user whether pyramids should be generated. This was implemented because the user of large static images has been largely replaced by dynamic images from web services, for which image pyramids do not improve quality, and greatly increase user confusion. | |||
If a user has a large static image, and desires to generate pyramids, the user’s preferences for building pyramids can be set in the ''Images'' tab of the [[SMS:Preferences|''Preferences'' dialog]] (''Edit'' | '''Preferences'''). | |||
== Related Topics == | == Related Topics == | ||
Revision as of 15:56, 28 August 2015
The XMS packages include an option to generate multiple resolution versions of an image when it is imported. This can improve the display quality of an image when the native resolution is much higher than the screen resolution. In essence, if the image resolution is larger than the screen resolution, a the display of the image skips pixels so the image appears discontinuous.
The process of generating multiple versions of the image is referred to as Image Pyramids. If the feature is invoked, XMS will average 2x2 blocks of pixels in the image creating an approximate version of the image at half the resolution. This process is repeated on the smaller image creating an image at one fourth the original resolution, and so on. Up to four images are generated, based on the relative native resolution and the screen resolution. The goal is to get an image in the pyramid that is approximately the same as screen resolution.
When displaying all or part of an image, XMS determines which of the pyramid images have a resolution that most closely matches the current screen pixel size and uses that version of the image.
There are a few points to keep in mind when building pyramids. The initial generation of pyramid files can take several minutes, depending on the size of the original image and the computer hardware. Building pyramids uses more memory RAM. Building pyramids may not improve the on screen display of all images.
Once an image pyramid has been built for a particular image file, the user will not be asked again to build pyramids for that image file unless the image is moved or altered.
When pyramids are built for an image, up to four JPEG images are saved to disk. These image files can be saved to a temporary folder or can be saved in the same directory as the original image so that they are not regenerated each time the image is loaded.
Image Preferences
For XMS versions released after summer 2015, the default option is to not generate image pyramids and not even ask the user whether pyramids should be generated. This was implemented because the user of large static images has been largely replaced by dynamic images from web services, for which image pyramids do not improve quality, and greatly increase user confusion.
If a user has a large static image, and desires to generate pyramids, the user’s preferences for building pyramids can be set in the Images tab of the Preferences dialog (Edit | Preferences).
Related Topics
GMS – Groundwater Modeling System | ||
|---|---|---|
| Modules: | 2D Grid • 2D Mesh • 2D Scatter Point • 3D Grid • 3D Mesh • 3D Scatter Point • Boreholes • GIS • Map • Solid • TINs • UGrids |  |
| Models: | FEFLOW • FEMWATER • HydroGeoSphere • MODAEM • MODFLOW • MODPATH • mod-PATH3DU • MT3DMS • MT3D-USGS • PEST • PHT3D • RT3D • SEAM3D • SEAWAT • SEEP2D • T-PROGS • ZONEBUDGET | |
| Aquaveo | ||
SMS – Surface-water Modeling System | ||
|---|---|---|
| Modules: | 1D Grid • Cartesian Grid • Curvilinear Grid • GIS • Map • Mesh • Particle • Quadtree • Raster • Scatter • UGrid |  |
| General Models: | 3D Structure • FVCOM • Generic • PTM | |
| Coastal Models: | ADCIRC • BOUSS-2D • CGWAVE • CMS-Flow • CMS-Wave • GenCade • STWAVE • WAM | |
| Riverine/Estuarine Models: | AdH • HEC-RAS • HYDRO AS-2D • RMA2 • RMA4 • SRH-2D • TUFLOW • TUFLOW FV | |
| Aquaveo • SMS Tutorials • SMS Workflows | ||
WMS – Watershed Modeling System | ||
|---|---|---|
| Modules: | Terrain Data • Drainage • Map • Hydrologic Modeling • River • GIS • 2D Grid • 2D Scatter |  |
| Models: | CE-QUAL-W2 • GSSHA • HEC-1 • HEC-HMS • HEC-RAS • HSPF • MODRAT • NSS • OC Hydrograph • OC Rational • Rational • River Tools • Storm Drain • SMPDBK • SWMM • TR-20 • TR-55 | |
| Toolbars: | Modules • Macros • Units • Digitize • Static Tools • Dynamic Tools • Drawing • Get Data Tools | |
| Aquaveo | ||
