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.
Viktiga funktioner
Om formatet JPEG 2000
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.
Vilket program öppnar JPEG 2000-filer
Följande program och applikationer kan öppna, redigera och arbeta med JPEG 2000 — Wavelet Image Compression-filer (.jp2) som exporterats från OSM2CDR:
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.
Vem använder JPEG 2000-kartor
Så exporterar du JPEG 2000
Så öppnar du filen efter exporten
- 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.
Populära kartor i JPEG 2000
Hämta kartexporter i JPEG 2000 — Wavelet Image Compression
Ladda ner professionella JPEG 2000-kartor från OpenStreetMap. Direktgenerering, valfritt område.