Does HEIC have wider dynamic range than JPEG?

[Dave_J_E]

I’m not familiar with Unix but QT is QuickTime (Apple) and is basically the .mov format. AVC is advanced video codec (h.264).

Dave

 

[Dave_J_E]

Yes, HEIC images (can) have a wider dynamic range.

To see the wider dynamic range, you need a display capable of displaying a wide dynamic range. Inside an image file you have a primary base image which is designed to display a standard dynamic range image. Yes the base image is a 24 bit RGB image (8:8:8) which is designed to have a SDR dynamic range. But there is more inside the file than just that. Most displays are 8 bit (or 8 bit + A-FRC) SDR, so the base image maps, very well to that kind of display. Many of the newer Apple displays have a wider dynamic range:

The dynamic range of HDR on Apple displays varies by device and model. HDR displays can have a dynamic range of up to 14 stops or more.

HDR dynamic range on Apple devices

• iPhones with XDR display: Up to 8x SDR EDR headroom

• iPad Pro's Liquid Retina XDR display: Up to 16x SDR

• Pro Display XDR: Up to 400x SDR in the default XDR preset

• Apple XDR Display (P3-1600 nits): Extreme Dynamic Range (XDR) support up to 1600 nits

As far as I know, all of these displays have the same peak brightness of 1600 nits. If the SDR white brightness level is set to 200 nits, this gives an EDR (Extended Dynamic Range) headroom of 8x or 3 stops.

HDR dynamic range on Mac models

• MacBooks Pro introduced in 2018 or later: Support HDR video on their built-in display

• MacBooks Air introduced in 2018 or later: Support HDR video on their built-in display, and on external HDR10-compatible displays

• iMacs introduced in 2020 or later: Support HDR video on their built-in display

These HDR displays are accommodated by the HEIC file also containing HDR GainMap data. This data is added onto the base image, data and pass through the display image processing pipeline to then appear on the display screen.

JPEG's can have embedded Gain Maps as well. However a Gain Map is not essential for HDR display. Files such as AVIF or JPEG XL can provide a straight HDR image. Gain maps are used to provide a satisfactory view of an HDR image on an SDR display.

HEIC and Image Depth

• Standard HEIC: The HEIC format is a container format and typically stores images with 8-bit per channel depth for standard photos on iPhones, as this is sufficient for most uses and keeps file sizes manageable.

• HDR HEIC: When an image is captured in HDR, it may use Apple’s proprietary enhancements, including computational photography techniques like Smart HDR, which merge multiple exposures to simulate a broader dynamic range. Even a single exposure can have gain map data, as the sensors have a wide dynamic range.

HDR Display and Dynamic Range

• On HDR-capable displays (like those found on modern iPhones and Macs), HDR images take advantage of the display’s ability to render a higher bit depth and brightness range. This doesn’t mean the stored image in the HEIC file is necessarily more than 8 bits per channel—it might still be 8 bits but mapped to a broader perceptual range.

• The rendering process on the display can interpolate or expand the dynamic range for HDR playback, making it look as if the image has more than 8-bit depth in practice.

Dynamic range is not directly related to bit depth. A higher bit depth just helps to avoid banding with an HDR display. Bit depth controls the size of the quantisation steps between max and min luminance with Dynamic Range defined as the ratio of max luminance to min..

Two Separate Exposures and Depth

• In HDR mode, Apple’s camera system typically captures multiple exposures (e.g., one for highlights and another for shadows) and combines them using tone mapping. But even images made from one exposure, may have the game map data to expand the dynamic range on a proper monitor.

• While the final image may be stored as an 8-bit HEIC file, the intermediate data during processing does use a higher bit depth (e.g., 10-bit or 12-bit) to ensure minimal loss of detail during merging.

• If exported in formats like ProRAW or other high-bit-depth options, these images can retain higher bit depths (e.g., 12-bit or 14-bit), suitable for professional editing.

In Summary

• Stored Image Depth: The HEIC file might still be 8-bit, but HDR enhancements rely on the merging of exposures and the capabilities of the display to simulate a higher dynamic range visually.

There are two types of HDR:

The "original" HDR which has been around for ages and involves blending of different exposures. This just gives an SDR view enhanced by tone mapping and having less shadow noise.

The "new" HDR which utilises higher dynamic range displays and this gives much improved highlight detail.

• Intermediate Processing: Even if the final file is 8-bit, the processing behind HEIC HDR images uses higher bit-depth data to ensure a broad dynamic range.

You can also tell by just looking at the images on a good display. So while the base image is 24 bit RGB, there is usually more data added, merged, and interpolated with each pixel thus on a good display the HEIC file appears with a wider dynamic range and smooth gradations -- effectively a 10 bit HDR.

 

[CAcreeks]

Thanks to jaberg and others, I found the button to turn off Live, and got an HDR image of the same scene at top of thread. Wow! Bright spots are very bright and detailed. Shadow detail is excellent, as it can be with JPEG.

Unfortunately I can't see the HDR effect except in Apple Photos. Export even to Unmodified HEIC loses the peak brightness when viewed in all other applications I have. Even Safari, currently the only browser that supports HEIC, shows dull.

Too bad. HDR is really nice. I'm happy with my XDR-1600 Macbook and HDR-1700 monitor. Hopefully software will catch up soon. HEIC seems a better solution than gainmaps.

 

[bakubo]

Thanks to jaberg and others, I found the button to turn off Live, and got an HDR image of the same scene at top of thread. Wow! Bright spots are very bright and detailed. Shadow detail is excellent, as it can be with JPEG.

Unfortunately I can't see the HDR effect except in Apple Photos. Export even to Unmodified HEIC loses the peak brightness when viewed in all other applications I have. Even Safari, currently the only browser that supports HEIC, shows dull.

Too bad. HDR is really nice. I'm happy with my XDR-1600 Macbook and HDR-1700 monitor. Hopefully software will catch up soon. HEIC seems a better solution than gainmaps.

Lightroom Classic can display HDR images properly on my Macbook Pro. Must select HDR mode in LrC though.

 

[CAcreeks]

Unfortunately I can't see the HDR effect except in Apple Photos.

Lightroom Classic can display HDR images properly on my Macbook Pro. Must select HDR mode in LrC though.

Do you or anyone know if regular Lr Lightroom has HDR mode, like LrC? Probably it does.

I'm not sure how Apple Photos decides to display HDR content without an HDR mode.

 

[Dave_J_E]

Unfortunately I can't see the HDR effect except in Apple Photos.

Lightroom Classic can display HDR images properly on my Macbook Pro. Must select HDR mode in LrC though.

Do you or anyone know if regular Lr Lightroom has HDR mode, like LrC? Probably it does.

I'm not sure how Apple Photos decides to display HDR content without an HDR mode.

Yes Lightroom (non classic) does have an HDR mode.

Dave

 

[rodeknyt]

Unfortunately I can't see the HDR effect except in Apple Photos. Export even to Unmodified HEIC loses the peak brightness when viewed in all other applications I have. Even Safari, currently the only browser that supports HEIC, shows dull.

Exporting an unmodified photo from Photos will never show what you can get within Photos. It only will export the original image without any of the processing Apple uses for the ancillary features (HDR, Live Photo etc.)

To get what you want you have to export the processed file. If you want to do more stuff to it in another application, export it as a TIFF or PNG.

 

[LuxLuthor]

Unfortunately I can't see the HDR effect except in Apple Photos. Export even to Unmodified HEIC loses the peak brightness when viewed in all other applications I have. Even Safari, currently the only browser that supports HEIC, shows dull.

Exporting an unmodified photo from Photos will never show what you can get within Photos. It only will export the original image without any of the processing Apple uses for the ancillary features (HDR, Live Photo etc.)

To get what you want you have to export the processed file. If you want to do more stuff to it in another application, export it as a TIFF or PNG.

I do believe that the original HEIC file has all the information, but to display HDR requires a proper display that can be shifted manually or automatically to an HDR display. Many displays will be showing a SDR profile and many displays aren't capable of HDR, but the info should be in the file.

Also, the software should be capable of utilizing the extra HDR data embedded in the HEIC file.

 

[CAcreeks]

I do believe that the original HEIC file has all the information, but to display HDR requires a proper display that can be shifted manually or automatically to an HDR display. Many displays will be showing a SDR profile and many displays aren't capable of HDR, but the info should be in the file.

Also, software should be capable of utilizing the extra HDR data embedded in the HEIC file.

Yes, I have Apple XDR and HDR displays (see below). Thus my interest in this question.

After more testing, I have concluded that non-Live HEIC from iPhone SE has more saturated greens and especially reds, with slightly better dynamic range, than non-Live JPEG. Too bad there are so few applications that deal with HDR. Affinity Photo is somewhat good at it, but not as good as Apple Photos on MacOS. Screen of iPhone SE is only HDR 10.