Test Bench

Sound & Vision - - TEST REPORT -

(For the con­trol set­tings used in this re­view, go to www. soun­dand­vi­sion.com)

The mea­sure­ments here were made us­ing CALMAN 2018 mea­sure­ment soft­ware from Por­trait Dis­plays/spec­tra­cal, to­gether with Photo Re­search PR-650 and Klein K-10A color me­ters and test pat­tern gen­er­a­tors from DVDO (AVLAB TPG) and Murideo/avpro (Fresco Six-g). The mea­sure­ments were taken in a to­tally dark­ened room.

1080P HD/SDR

FULL-ON/FULL-OFF CON­TRAST RA­TIO: Un­mea­sur­able (Lo­cal dim­ming on Medium)

The mea­sure­ments were taken in the Cin­ema Home Picture Mode with the Black Level con­trol set to 50, Bright­ness (back­light) at 10, Con­trast at 85, Gamma at -2, X-tended Dy­namic Range off, and us­ing an 18% full white win­dow for a mea­sured peak white level of 42.1 foot-lam­berts (143 nits). With a full black screen in­put, the lo­cal dim­ming shut down the screen bright­ness to to­tal black for an un­mea­sur­able re­sult (it would be mis­lead­ing to call this in­fi­nite con­trast, though math­e­mat­i­cally it is). With the Lo­cal Dim­ming mode off, the con­trast ra­tio dropped to 2,216:1 in these con­trol set­tings.

In the Ex­pert 1 color tem­per­a­ture mode with the above set­tings, the pre-cal­i­bra­tion grayscale Delta E from 20% to 100% var­ied from 1.15 at 20% to 2.09 at 70%, an ex­cel­lent re­sult. Post-cal­i­bra­tion, the Delta Es var­ied from a min­i­mum of 0.3 at 90% to a max­i­mum of 1.30 at 100%. Though the X900F has no CMS (color man­age­ment sys­tem), the post cal­i­bra­tion color Delta Es var­ied from a min­i­mum of 0.91 (red) to a max­i­mum of 1.65 (yel­low).

(Delta E is a fig­ure of merit in­di­cat­ing how close the color comes to the stan­dards, ei­ther D65 for the white point (gray scale), or the color co­or­di­nates for each of the pri­mary and sec­ondary col­ors that de­fine the color gamut un­der test. Val­ues be­low 3— some ex­perts al­low for 4— are gen­er­ally un­no­tice­able).

With the Gamma con­trol at -2, the Sony’s 1080P/SDR gamma ranged from a high of 2.43 at 90% to a low if 2.37 at 20%.

UHD/HDR

FULL-ON/FULL-OFF CON­TRAST RA­TIO: Un­mea­sur­able (Lo­cal dim­ming on Medium)

The Af­ter mea­sure­ments were taken in the Cin­ema Pro Picture Mode with the Black Level con­trol at 50, the Bright­ness at Max, the Con­trast at 90, the Gamma at 0, and X-tended Dy­namic Range on High. With a 10% full white win­dow, the mea­sured peak white level was 297 ft-l (1,018 nits). With a full black screen in­put the lo­cal dim­ming shut down the screen bright­ness to to­tal black for an un­mea­sur­able re­sult. With Lo­cal Dim­ming off, the con­trast dropped to 5,211:1— a higher num­ber than for SDR with no lo­cal dim­ming pri­mar­ily due to HDR’S higher peak white.

The peak white out­put for HDR varies sig­nif­i­cantly with how much of the screen is cov­ered with a peak white im­age— as it does to vary­ing de­grees with all dis­plays we’ve tested to date. In the X900F'S case, it mea­sured 480 nits at 2%, 857 nits at 5%, 1018 nits at 10%, 908 nits at 25%, and 634 nits at 100%.

Sony has cho­sen to per­form its tone map­ping us­ing an EOTF PQ curve (gamma for HDR) that’s lower in bright­ness over much of its pre-clip­ping range than the stan­dard HDR EOTF. This de­lays clip­ping to a higher level, but also pushes the Delta E val­ues dra­mat­i­cally higher if lu­mi­nance is in­cluded in the Delta E cal­cu­la­tion. With­out in­clud­ing lu­mi­nance, how­ever, the post cal­i­bra­tion HDR Delta Es were be­low 2.0 at all lev­els. The er­rors were great­est in the mid­dle of the bright­ness range, and re­peated at­tempts to use the set’s 10-point Ad­vanced Color ad­just­ments failed to cure the sit­u­a­tion. For­tu­nately, it pro­duced no vis­i­ble is­sues.

The HDR color checker test in­ves­ti­gates a wide va­ri­ety of pos­si­ble col­ors in ad­di­tion to the usual pri­maries and sec­on­daries (red, green, blue, cyan, ma­genta, yel­low)—col­ors such as dark skin, light skin, blue sky, fo­liage, etc. This test also pro­vided good re­sults with­out lu­mi­nance in­cluded, with an av­er­age Delta E of 1.48.

The Sony cov­ered 69.4% of the B.T. 2020 color gamut (lim­ited mainly by its in­abil­ity to reach B.T.2020 green, a short­com­ing com­mon to vir­tu­ally all of to­day’s dis­plays), and 94.4% of P3 (us­ing the 1976 CIE stan­dard for both re­sults). Full B.T. 2020 cov­er­age is cur­rently of lit­tle rel­e­vance as vir­tu­ally all cur­rent UHD pro­gram ma­te­rial is mas­tered in P3.

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