True HDR editing

[miric]

I’m trying to bring out more luminance in my photos on my MacBook Pro with an XDR display. When I increase Exposure, Lights, or Whites to expand the histogram into the extra HDR stops, the colors end up looking like they came from an acid festival.

When I check the exported HDR photo in the Gain Map Demo App, I notice that the gain map contains colors. However, when I look at HDR photos from Instagram or the Radiance+ app on iOS, their gain maps appear monochrome.

Why is it like that, and how can I change it? Also, why does adjusting the HDR version of the photo affect the SDR version too? I already have a finalized SDR photo—I just want to add luminance for HDR without altering the SDR image.

[Noel Orridge]

Hi @miric, Thank you for reaching out! We're here to help!

Your gain map has colors because pushing Exposure/Lights/Whites too far for HDR in Lightroom Classic can introduce color shifts and clip colors, which then get recorded as colored adjustments in the gain map. Ideal gain maps are monochrome (grayscale) as they primarily describe luminance changes for clean HDR.

My suggestion is to avoid over-pushing global sliders. Use local adjustments for targeted luminance boosts, and be ready to desaturate highlights if they become oversaturated.

Also, HDR files with gain maps contain SDR and HDR data, sharing a base image. Global edits affect both. It'd be better to finalize your SDR edit first, then make HDR adjustments, and finally use the SDR Rendition Settings to fine-tune how the SDR version looks without altering the HDR data. This lets you maintain your original SDR look while providing full HDR luminance.

Hope this helps! 

[miric]

Hi Noel. Thank you for your response.

I’m really curious how the iOS app Radiance+ manages everything with just two sliders and without all the extra steps. Maybe it’s not as flexible as Lightroom, but it just works and makes achieving the desired result much easier. Lightroom, on the other hand, seems to overcomplicate things.