Sony A90K SDR Calibration Overview

The A90K is a UHD (3840x2160) WOLED TV from Sony, delivering deep blacks and vibrant colors. The display is a popular choice for home theater and is also occasionally used in color/edit bays as a client review display.

Below is an overview of the performance of the 48" model before and after professional Sony A90K calibration.
A 3D LUT calibration was done to achieve the best possible results.

Notes:

  1. resulting cLUT was loaded into the BMD Micro Converter LUT box, the A90K does not have internal LUT storage
  2. an alternative white point (AWP) target could have been used in the calibration, as these WOLED panels can trigger metamerism in observers

Equipment, software and target used in the calibration:

  • Calibration software: DCM
  • Colorimeter: K-10-A
  • Spectro: CR-300
  • Patch generator: DaVinci Resolve, SDI out
  • Calibration target: Rec 709 D65 G2.4 100 nits (SDR)
  • LUT holder: BMD Micro Converter 33^3

Native Gamut

This is the native gamut (before calibration) of the Sony A90K compared to the Rec 709 color space calibration target. The display's native gamut fully covers the target color space, making it ideal for precise display calibration. The white point is on target, after manual calibration using the CMS gain controls.

Sony A90K SDR native gamut pre calibration

RGB Balance

This is the Greyscale RGB balance before LUT calibration, after manual calibration using the CMS bias/gain controls - a blue tint remains.

Sony A90K SDR RGB balance pre calibration

EOTF: Gamma

This is the native gamma and luminance response of the Sony A90K. The reference line is configured for the calibration target of G2.4. In its default native state, the display's brightness is significantly higher than the calibration target.

Sony A90K SDR EOTF gamma tracking pre calibration

Spectrum Analysis

This is the spectrum of the Sony A90K in native gamut for full white, with the red, green and blue primaries spectral output overlaid to identify color channel issues. The W channel does not closely track the R, G, B color channels (B channel performs best), this is a consequence of WOLED display technology.

Sony A90K SDR spectrum of the display in native gamut for white, red, green, blue

Calibration

After display preparation and configuration, a large display profile is run to create a detailed characterization of the display. From that profile data, a 3D LUT is then generated by DCT and loaded into the BMD Micro Converter LUT box.

Gamut & White Point (post)

Gamut (post calibration) compared to the Rec 709 D65 target - both color space and white point are on target.

Sony A90K SDR gamut & white point post calibration

RGB Balance (post)

This is the Greyscale RGB balance post-calibration, excellent result.

Sony A90K SDR RGB balance post calibration

EOTF: Gamma (post)

This is the gamma and luminance response of the Sony A90K after calibration compared to the reference calibration target G2.4. The display now tracks the reference much closer than before.

Sony A90K SDR EOTF gamma tracking post calibration

Color Error: delta E 2000 (post)

These are the dE 2000 stats post calibration for a 1,100 point stress test validation profile. With an average dE 2000 color error of only 0.47, the Sony A90K now performs exceptionally well given that the JND (just noticeable difference) for human vision is set at a dE 2000 value of 2.3.

Sony A90K SDR delta E stats post calibration for stress test validation profile


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