Quick way to resize .hdr maps?

I have some very large HDRI environment maps that I’d like to resize so they don’t eat up as much disk space/Blender memory. I’m looking for a solution that will run on Windows.

I realize that I could bring in a large HDRI map into Blender and render out a panoramic map at a lower resolution…but I’d like a quicker way of doing this.

I tried opening .hdr files in Krita (which supposedly supports HDRI) but Krita crashes. I’ve looked for free applications for Windows that can work with .hdr files but for whatever reason most of those applications are dead (the web sites are gone).

This seems like it should be an easy thing to do, but I’ve not been able to find a satisfactory/easy answer yet. Any suggestions?

Have you tried XnView?

Yes, and it opens a HDR file and resizes it…but I can’t figure out how to save it as a .HDR file. There’s no .HDR file output option:

Even if I just try to save over the existing file (instead of doing a Save As), it prompts me for a file name with a file type (.HDR not being one of the options).

Of course, maybe I’m missing something here…

Loading them into Blender’s compositor and rendering the comp out at a smaller size is probably the easiest and most reliable way with free software. You can save the result as either Radiance HDR or OpenEXR, Blender supports both. OpenEXR has better dynamic range, but if you’re starting from an .hdr file anyway that doesn’t matter.

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Affinity Photo can do it. It’s not free but is cheap for what it can do and they do offer a 90 day trial.

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Do you have photoshop? There is a script to batch process photos. You should be able to resize all of your maps to a specific size and save them to a new folder that you just name (x)k_hdri or whatever and it will handle it for you. Blender typically can save and open 32 bit files just fine, affinity photo is just better for editing them (at least out of the box it is)

Picturenaut do this, but not have Batch Convert. Search on the Google.

And I writing a program for Batch HDR operations (converting, resizing, tonemaping, color operations, histogram operations etc.) for Windows OS. I do not intend to go on sale now, but near future maybe can I will put on the market.

Thanks, @HikmetPicturenaut is exactly what I was looking for! :+1:

Photoshop can ,in better way