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Lecture 25: Image Sensors (34)
sberkun

Is this HDR technique the same thing as HDR for TVs and monitors? If so, how does a monitor use the extra information?

mcjch

@sberkun HDR for TV expands the range of contrast and color for brightness in images, so I think they are the same techniques.

https://www.pcmag.com/news/what-is-hdr-high-dynamic-rangehttps://www.pcmag.com/news/what-is-hdr-high-dynamic-range

jacklishufan

@sberkun the concept is a bit different. The HDR means High Dynamic Range in displaying information for TV and Display. This is typically achieved by replacing the uint8 (0-255) representation with uint32 which retains more information. However, this slide focuses on one of the possible ways to obtain such raw information in the first place. Tho it is not the only way. (For example, there are ML algorithms that "predict" HDR images from standard images, and it is possible to render an HDR video directly in CGI/Animation context. So In general, they are not the same concept.

jacklishufan

To make use of more information, HDR screens are simply brighter, hence they can display a large range of brightness.

sberkun

@jacklishufan I think you're right, here's an article I found explaining the difference. The same author also wrote a full article on display hdr.

It sounds like display HDR uses 10-bit color, and an Electro Optical Transfer Function to map those colors to brightness values.

ld184

most modern phone does HDR computation by default. I wonder how many images do these phones sensors need to start correctly interpolating values at different regions of the shot?

Unicorn53547

I think the number of photos needed is dependent on the camera setting. Adobe provides such support for mergeing photots to HDR. They provide somr details about number of photos needed here

JustinHuey1

Here is a good article that goes in depth on how to achieve high quality images using HDR. I think that it could be insightful and answer some of your questions.

https://www.veneratech.com/hdr-transfer-functions-hlg-pq/

modatberkeley

Pretty cool paper about multiple exposure imaging on mobile devices (from 2010!) if anyone wants to understand more: Link

modatberkeley

It should be noted, though, that modern implementations also rely on machine learning to achieve better results — especially since in real life, there are inconsistencies as frames not lining up due to movement, etc.

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