JPG + JGW to GeoTIFF: keep your image’s map position

Have a JPG image and a small JGW file beside it? Select both in Recast to write a TIFF with the available positioning stored inside. The conversion runs on your device, without uploading either file.

By Recast · Published 8 September 2026

What are the two files for?

The JPEG contains the image pixels. Its world file describes their size, rotation, and position. GDAL can read JPEG world files with .jgw, .jpgw, .jpegw, or .wld extensions; see the JPEG driver documentation. This is a practical way to bring an already-positioned image into a TIFF workflow.

A world file does not define the coordinate reference system (CRS). Numbers describing a position are not enough to establish which coordinate system those numbers belong to. Recast retains the positioning it can read and warns when no CRS is defined.

How to convert JPG and JGW to GeoTIFF

1. Keep the original files. Check that the names match: for example, campus.jpg and campus.jgw.
2. Open Recast and select both files together. The image can end in .jpg or .jpeg. Include only one matching world file.
3. Wait for inspection, then review the image dimensions, bands, coordinate system, and positioning. A missing-CRS warning still matters even if positioning was found.
4. Choose GeoTIFF and click Make compatible with QGIS. Recast decodes the JPEG pixels and writes a tiled TIFF using DEFLATE compression.
5. Save the download and open it in QGIS. If Recast supplies a ZIP, extract it and keep its files together. Check the extent and alignment against a trusted layer. If the CRS is missing, obtain the correct definition from the data provider before assigning it.

Will the map stay in the same place?

Recast checks that the output dimensions and available geotransform match the source. It does not intentionally reproject or resize this conversion. That preserves the positioning supplied by a valid world file; it does not establish that the original positioning or CRS is correct.

For a JPEG accompanied only by a world file, expect to identify the CRS separately. Recast does not accept a standalone .prj as a JPEG companion in this workflow. Its .prj support is for ASCII Grid input.

What if I only have the JPEG?

You can still convert it to TIFF, but changing the format does not locate an unpositioned image on a map. EXIF GPS tags do not establish raster georeferencing in GDAL’s JPEG reader. Ask for the matching world file or georeference the image in a GIS application.

Will this improve image quality?

DEFLATE introduces no further lossy compression to the decoded pixels. It cannot restore detail already lost when the JPEG was created, and the TIFF may be larger than the JPEG. This conversion is intended for GIS compatibility and available positioning, not photo enhancement.

Common reasons conversion stops

• Names do not match: use the same base name for the image and world file.
• More than one world file: select the correct one, rather than passing conflicting versions.
• Invalid world file: it must contain six valid numbers defining a nonzero pixel grid.
• Read or memory error: the browser engine must decode the image, and the file and memory limits apply.

This workflow addresses the same practical need described in this question about converting a georeferenced JPG and JGW to TIFF. If your image instead triggers a JPEG decoder error, see our QGIS JPEG library troubleshooting guide.