How to identify an HDR image?

[XilburQost]

My apologies if this is a little off-topic, but I'm not sure where else to ask. I'm new to HDR and I downloaded some Shutterstock panoramas (https://www.shutterstock.com/image-photo/blue-sky-panorama-cirrus-clouds-seamless-2104429550) advertised as being HDR, but I'm not convinced they are actually HDR. Photoshop tells me that the images are 8-bit jpegs. Is there a feature or procedure in Photoshop that will reveal whether an image is HDR? Thanks. Photoshop 23.1.1, Windows 11

[Ged_Traynor]

Hi

Srcoll down to the "Edit Panoramas" bit in the below link

https://helpx.adobe.com/photoshop/using/create-panoramic-images-photomerge.html

[Chuck Uebele]

Once an image is saved down to to an 8bit jpg, you really can't see how it was processed. You really just have to go by the brightness levels of the image. I noticed some of those cloud images had the sun in them, that normally really blows out the detail, so you just have to gauge the age by your knowledge of what a non HDR would look like. An HDR shouldn't have excessive noise in the shadows. A single exposure where the shadows were boosted normally shows more noise.

[D Fosse]

An 8 bit jpeg is by definition not an HDR image. It may be the result of processing an HDR image, but nothing more.

An HDR file is 32 bits per channel, containing information outside the normal white and black points of a standard gamma encoded image. This extended dynamic range is what defines it as HDR (High Dynamic Range).

[XilburQost]

Thank you for the responses, everyone. I have some HDR images in EXR format that are 32 bits per channel and when I adjust their exposure (in a 3D app called Blender) I can see the advantages. Meanwhile, if I adjust the exposure of the alleged HDR 8 bit images from Shutterstock the highlights either are blown out or reduced to a dull gray. 

[D Fosse]

It's totally meaningless to call a jpeg "HDR". It rather indicates they don't understand what it means. There's no way to know where an image comes from, and it doesn't even matter. It could just as well be a raw file, which can also contain more information than will be used in the final image.

To some of us, HDR has negative associations. Uncritical HDR processing usually produces a compressed and very unnatural look. HDR is a tool, and it needs to be used wisely.

[XilburQost]

I contacted Shutterstock and the chat rep did not appear to have any idea what I was talking about. She told me that the 8-bit jpegs was all they had available, despite being labeled HDR. 

[Chuck Uebele]

Once an HDR image is saved to jpg, it is no longer an HDR, so you can't adjust it without getting the grays that you mentioned.