It is common in smartphone applications to have a window of HDR (high dynamic range) content against an SDR (standard dynamic range) background. Due to differences in supply voltages and refresh rates between HDR and SDR, luminance can be discontinuous at the HDR-SDR boundary, resulting in visual anomalies, flicker, and perceptual difficulties. This disclosure describes techniques to provide a smooth HDR-SDR transition during blended HDR-SDR operation. A raw gamma curve, e.g., as set by the display manufacturer, is recomputed such that a target luminance is met at a different refresh rate. A smooth SDR-HDR transition is obtained by applying the recomputed gamma curve at or near the SDR-HDR boundary. Smooth transition is achieved in both luminance and color. The techniques are operable under typical environments of multiple refresh rates, supply voltages, and brightness modes. A user experience that is free of visual anomalies, flicker, and perceptual difficulties results.

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This work is licensed under a Creative Commons Attribution 4.0 License.