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I am working with georeferenced raster images in pseudo mercator (3857). They are in TIFF with TFW- and JPG with JGW world files. The TIFFs are also available tiled. I'd like to be able to transform either of these file types to OS/GB 27700 crs (preferably the JPG/JGW). While retaining the file format as is.

Is it possible to do this in JPG without changing to TIFF as an intermediate step?

If not, is there a way to transform the TFW file along with the new TIFF?

My experiments so far have been of mixed success. Black images, or images that are only a tiny part of the original. Through the "save as"- and "raster translate" routes.

I am now working with the JPGs. I can get the raster translate to work - creates images that have been warped. However they are produced with a new black outline, which isn't ideal (though can be cropped externally I would suppose).

Is there a way to carry-out the geoTIFF warp without producing the black cutline?

That said, main issue is I need a JGW file to accompany these renders.

Is there a routine for creating JGW file for an existing JPG?

QGIS example is here: https://www.dropbox.com/s/zzqfw7hoi2v3tjv/Basic%20JPGs%200.1.qgs?dl=0 And JPG file folder (including failed renders), here: https://www.dropbox.com/sh/bxxmcvb2wrb9gl4/AACi6S6GKGPpcLUWT0o_-nKAa?dl=0

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  • Have a read of GDAL warp gdal.org/gdalwarp.html, available from QGIS interface docs.qgis.org/2.18/en/docs/user_manual/plugins/…. Warping JPG->JPG isn't a problem but the raster must be resampled during a warp operation and as JPEG is already a lossy compression it would make the artifacts worse, best to input TIFF and output JPEG if you have the option. – Michael Stimson Feb 20 '18 at 5:52
  • Thanks, agree TIFF work path is wise. Have been warping, perhaps successfully. They overlay correctly. And seem to have correct coordinates (insertion I guess). Can I create a TFW in the same pass? Or must it be through Translate? Am struggling with this stage. Thanks for this – ensta Feb 20 '18 at 6:09
  • As per the Tour there should be only one question asked per question. – PolyGeo Feb 20 '18 at 11:40
  • If you want a TFW file (which can be renamed to JGW for JPG files) use the GeoTIFF creation option -co TFW=YES, see gdal.org/frmt_gtiff.html you should be able to edit that into the command line options if you're calling warp via GDAL tools plugin. – Michael Stimson Feb 20 '18 at 21:37