orm08 skrev:HDR er blot konstrueret som som nådesstødet til plasma nørderne der sad nede i deres mørke kælder og diskuterede hvis plasma tv der viste det bedste sort ?
Jo, med de meget høje lysstyrker der snakkes om ved HDR, så skulle man tro at det var slut med at tage hensyn til rummets belysning som det kunne være nødvendigt med plasma TV der typisk kun kunne levere omkring 100 nits. Med LCD og OLED har man jo vænnet sig til at man bare kan øge lysstyrken hvis TV'et f.eks. står i en lys stue, men som det fremgår af uddragene nedenfor fra en artikel på Lightillusion.com, så er det ikke muligt ved HDR.
Hvis man ser en film i HDR, så vil det meste af indholdet (mørke og 'normale' scener/partier) have ca. den samme lysstyrke som hvis man så en SDR version af filmen på et TV kalibreret til 100 nits, og det er sjovt (eller ironisk) nok den samme relativt lave lysstyrke som mange plasma TV maksimalt kunne præstere. De høje lysstyrker ved HDR, det er kun en reserve der tages i brug ved ekstra lyse partier som f.eks. lygter/lyskilder, refleksioner eller en hvid sky.
Kan anbefale at læse hele artiklen hvis man vil vide lidt mere om hvad HDR egentlig er for noget. For mig fik den mange ting til at falde på plads.
https://www.lightillusion.com/uhdtv.html
"The biggest confusion with regard to HDR is that it is not attempting to make the whole image brighter, which unfortunately seems to be the way most people think of HDR, but aims to provide additional brightness headroom for spectral highlight detail - such as chrome reflections, sun illuminated clouds, fire, explosions, lamp bulb filaments, etc. "
"The PQ based ST2084 HDR specification defines reference white (normal diffuse white) as being 100 nits, which is exactly the same as for SDR (Standard Dynamic Range) displays, as specified for mastering (grading) grade-1 applications. With PQ HDR, above 100 nits is for spectral highlight detail only. This shows that the Average Picture Level (APL) of a PQ HDR display will not be significantly different to a SDR display.
Regardless of the maximum peak brightness the display can generate, diffuse white will always be around 100 nits. "
"Whilst we know and understand that the SDR grading display will have been calibrated to 100 nits, we also understand that it will have been housed in a controlled grading environment, with little ambient light. The beauty of SDR's relative approach to gamma is that the TV can simply be made brighter to overcome uncontrollable light contaminated environments, including the use of different gamma values.
One of the often overlooked potential issues with PQ based HDR for home viewing is that because the standard is 'absolute' there is no way to increase the display's light output to overcome surrounding room light levels - the peak brightness cannot be increased, and neither can the fixed gamma (EOTF) curve.
As mentioned above, with HDR the Average Picture Level (APL) will match that of regular SDR (standard dynamic range) imagery. The result is that in less than ideal viewing environments, where the surrounding room brightness level is relatively high, the bulk of the HDR image will appear very dark, with shadow detail potentially becoming very difficult to see.
To be able to view PQ based 'absolute' HDR imagery environmental light levels will have to be very carefully controlled. Far more so than for SDR viewing. This really does mean using a true home cinema environment. "