JPEG 2000 — Wavelet Image Compression
Open BetaJPEG 2000 (.jp2) is the ISO/IEC 15444 international standard that uses a wavelet transform instead of the block DCT of ordinary JPEG. On osm2cdr.ru the map is rendered to PNG and then converted to .jp2 through GDAL's JP2OpenJPEG driver. Wavelet compression gives graceful degradation without blocky artefacts and multi-resolution decode. Both lossy and lossless modes are supported. The output is a raster RGB image of the map (not a multi-band satellite scene); it is a compact replacement for heavy PNG in high-resolution map posters and raster overlays.
Sleutelkenmerke
Oor die JPEG 2000-formaat
JPEG 2000 is the ISO/IEC 15444 standard, built on a wavelet transform instead of the block DCT of ordinary JPEG. Hence its character: under heavy compression the picture blurs smoothly, without square artifacts, and a lower resolution can be read out of a single file without unpacking the whole image.
In cartography the format took root in archives and raster libraries: aerial photography, map scans and large rasters are stored as .jp2 for years. Multi-level decoding makes viewing large images fast — the program reads exactly the level it needs for the screen.
With us the map is rendered to PNG and then converted to .jp2 by the GDAL JP2OpenJPEG driver. The output is an ordinary RGB image of the map: a compact replacement for a heavy PNG in high-resolution posters and raster overlays. Lossy compression is applied by default, and a reversible lossless mode is available too.
What is not in the file: the spectral bands of a satellite scene and vector features. This is a snapshot of the map, not a multi-band raster and not a set of layers — OpenStreetMap tags do not make it in.
Watter program open JPEG 2000-lêers
Die volgende programme en toepassings kan JPEG 2000 — Wavelet Image Compression (.jp2)-lêers wat uit OSM2CDR uitgevoer is, open, redigeer en daarmee werk:
Format specifications
- Open standard
- 2D only
- Lossy compression
- No attributes
- Output: 1 file
- A single .jp2 (ISO/IEC 15444) converted from PNG via the GDAL JP2OpenJPEG driver; wavelet compression, lossy by default with multi-resolution decode, an RGB map snapshot.
Wie gebruik JPEG 2000-kaarte
Hoe om JPEG 2000 uit te voer
Hoe om dit ná uitvoer te open
- QGIS (free) — Layer → Add Raster Layer; the JP2OpenJPEG driver ships with GDAL and is already installed.
- GDAL — gdalinfo map.jp2 shows the dimensions and resolution levels, and gdal_translate converts the file into GeoTIFF or PNG.
- ImageMagick or IrfanView with a plugin — viewing and batch conversion on the desktop.
- Print and layout — Photoshop and InDesign open .jp2; if the print shop asks for a familiar format, hand them a TIFF made from the same file.
Gewilde kaarte in JPEG 2000
Kry JPEG 2000 — Wavelet Image Compression-kaartuitvoere
Laai professionele JPEG 2000-kaarte van OpenStreetMap af. Onmiddellike generering, enige gebied.