Graphics blending for high dynamic range video
A method and system for merging graphics and high dynamic range video data is disclosed. In a video receiver, if needed, video and graphics are translated first into the IPT-PQ color space. A display management process uses metadata to map the input video data and the graphics from their own color volume space into a target blending color volume space by taking into consideration the color volume space of the target display.
1. In a video receiver, a method for blending graphics data, the method comprising:
receiving input graphics data at a graphics dynamic range;
receiving an input video signal at a video dynamic range, wherein the video dynamic range is higher than the graphics dynamic range;
determining a target display dynamic range;
determining a relationship between the target display dynamic range and the graphics dynamic range or between the target display dynamic range and the video dynamic range, wherein upon determining that the target display dynamic range is higher than the graphics dynamic range but lower than the video dynamic range:
applying a receiver display management process to the input graphics data to generate mapped graphics data, wherein the display management process maps the input graphics data from the target display dynamic range to the video dynamic range;
blending the mapped graphics data with the input video signal to generate a composite video signal at the video dynamic range; and
outputting the composite video signal.
2. The method of claim 1 , further comprising:
in a television set, receiving the composite video signal; and
applying a TV display management process to the composite video signal to generate a target display signal at the target display dynamic range.
3. The method of claim 1 , further comprising:
applying in the video receiver a second display management process to the composite video signal to generate a target display signal at the target display dynamic range.
4. The method of claim 1 wherein upon determining that the target display dynamic range is equal to the graphics dynamic range:
applying a receiver display management process to the input video signal to generate a mapped video signal, wherein the display management process maps the input video signal from the video dynamic range to the target display dynamic range;
blending the graphics data with the mapped video signal to generate the composite video signal at the target display dynamic range; and
outputting the composite video signal.
5. The method of claim 1 wherein upon determining that the target display dynamic range is equal to the video dynamic range:
applying a receiver display management process to the input graphics data to generate mapped graphics data, wherein the display management process maps the input graphics data from the graphics dynamic range to the target display dynamic range;
blending the mapped graphics data with the input video signal to generate the composite video signal at the target display dynamic range; and
outputting the composite video signal.
6. The method of claim 1 , wherein upon determining that the target display dynamic range is higher than the graphics dynamic range but lower than the video dynamic range:
applying a first receiver display management process to the input graphics data to generate mapped graphics data, wherein the first display management process maps the input graphics data from the graphics dynamic range to the target display dynamic range;
applying a second receiver display management process to the input video signal to generate a mapped video signal, wherein the second display management process maps the input video signal from the video dynamic range to the target display dynamic range;
blending the mapped graphics data with the mapped video signal to generate the composite video signal at the target display dynamic range; and
outputting the composite video signal.
7. The method of claim 1 , further comprising:
determining whether the input video signal and/or the input graphics data are in a perceptually quantized IPT color space, and if not, converting the input video signal and/or the input graphics data from their original color space to the perceptually quantized IPT color space; and
performing blending in the perceptually quantized IPT color space.
8. The method of claim 7 , wherein the IPT perceptual quantization is performed according to SMPTE ST 2084.
9. The method of claim 1 , further comprising:
receiving input metadata;
generating blended signal metadata based on the input metadata; and
outputting the blended signal metadata.
10. The method of claim 9 , wherein the input metadata comprise a maximum graphics brightness value for the input graphics data and a maximum video brightness value for the input video signal, and the blended signal metadata comprise a maximum blended video brightness value for the composite video signal, and generating the blended signal metadata comprises:
computing the maximum blended video brightness value as the maximum of the maximum graphics brightness value and the maximum video brightness value.
11. The method of claim 10 , wherein the input metadata further comprise a minimum graphics brightness value and a minimum video brightness value, and the blended signal metadata comprise a minimum blended video brightness value, and generating the blended signal metadata comprises:
computing the minimum blended video brightness value as the minimum of the minimum graphics brightness value and the minimum video brightness value.
12. The method of claim 11 , wherein the input metadata further comprise a mean video brightness value and the blended signal metadata comprise a mean blended video brightness value, and the mean blended video brightness value is set to be equal to the mean video brightness value.
13. The method of claim 9 , wherein the input metadata comprise:
a minimum dynamic range for a video source display,
a maximum dynamic range for the video source display,
an average (mean) dynamic range for the video source display,
a minimum dynamic range for a graphics source display, and
a maximum dynamic range for the graphics source display, and the blended signal metadata comprise a maximum blended video brightness value, a minimum blended video brightness value, and an average blended video brightness value, and generating the blended signal metadata comprises:
computing the maximum blended video brightness value as the maximum of the maximum dynamic range for the video source display and the maximum dynamic range for the graphics source display;
computing the minimum blended video brightness value as the minimum of the minimum dynamic range for the video source display and the minimum dynamic range for the graphics source display; and
computing the average blended video brightness value as the average dynamic range for the video source display.
14. A non-transitory computer-readable storage medium having stored thereon computer-executable instruction for executing a method with a computer in accordance with claim 1 .