What Is an HDR File?
A file with the HDR file extension is a high dynamic range image file. Images of this type aren’t generally distributed, but instead edited and then saved to a different image format, like TIFF. Geographic Information System (GIS) files that contain information on the format and layout of an ESRI BIL file (.BIL) are called ESRI BIL Header files, and also use the HDR file extension. They store information in the ASCII text format.
How to Open an HDR File
HDR files can be opened with Adobe Photoshop, ACD Systems Canvas, HDRSoft Photomatix, and probably some other popular photo and graphics tools as well. You might also have luck with the online viewer at OpenHDR.org if you want to open it online, or RenderStuff.com. If your file isn’t an image but instead an ESRI BIL Header file, you can open it with ArcGIS, GDAL, or Global Mapper.
How to Convert an HDR File
Imagenator is one free file converter that can convert an HDR file. It supports batch conversions between several image formats, including HDR, EXR, TGA, JPG, ICO, GIF, and PNG. Another good option for online conversions is Convertio. You can also open one in one of the programs from above and then save it to a different image file format. Photoshop can save an HDR file to PSD, EXR, RAW, TIFF, PBM, and other image formats. If an ESRI BIL Header files can be converted to any other format, it’s most likely accomplished through one of the programs linked above. Typically, the option for converting a file in a program like one of those is available through the File > Save As menu or some type of Export option. If you need to convert HDR to cubemap, CubeMapGen may be what you need.
Still Can’t Open the File?
If your file isn’t opening with any of the programs described above, you could be misreading the file extension, mistaking another file format for this one. If this happens, you’ll probably receive an error when trying to use the file with an HDR-compatible program. Some examples of file extensions that closely resemble this one and that could be easily confused for it, include HDS (Parallels Desktop Hard Disk), HDP (HD Photo), and HDF (Hierarchical Data Format).
