Methods and apparatus for processing and or encoding images with negative parallax
Encoding and streaming methods and apparatus are described. Objects in negative parallax in frame pairs, e.g., pairs of left and right eye images forming a stereoscopic image, are identified. An amount of negative parallax reduction implemented depends, in some embodiments, on the data rate being used for encoding and/or the amount of negative parallax detected in the frame pair to be encoded. The lower the supported data rate the greater the reduction in negative parallax in some embodiments. In some, but not all, embodiments objects in positive parallax, e.g., objects appearing to go into the page, are not subject to parallax reduction. When a lowest supported data rate is used mono encoding is used and parallax reduction steps are skipped. The same frame pair is encoded multiple times at different data rates. Different amounts of negative parallax reduction are performed for at least some of the different supported data rates.
1. A method of encoding stereoscopic image data, the method comprising:
identifying a frame pair to be encoded;
encoding the frame pair, using a first bit rate, to form first encoded data; and
encoding the frame pair, using a second bit rate that is lower than the first bit rate, to form second encoded data by:
identifying an object in the frame pair in negative parallax;
determining an amount of negative parallax reduction to perform on the object in negative parallax as a function of the second bit rate used to encode the frame pair;
performing the determined amount of negative parallax reduction on the object; and
encoding the frame pair using the second bit rate without performing parallax reduction on objects in positive parallax.
2. The method of claim 1 , further comprising:
identifying a second object in negative parallax in the frame pair; and
determining a parallax difference between the object in the negative parallax in the frame pair and the second object in negative parallax in the frame pair.
3. The method of claim 2 , wherein the amount of negative parallax reduction performed is also a function of the parallax difference.
4. The method of claim 1 , wherein encoding the frame pair using the first bit rate comprises:
determining a second amount of negative parallax reduction to perform on the object in negative parallax as a function of the first bit rate, the second amount of negative parallax reduction being less than the amount of negative parallax reduction determined as a function of the second bit rate;
performing the second amount of negative parallax reduction on the object; and
encoding the frame pair using the first bit rate.
5. An image processing system for processing stereoscopic image data, the image processing system comprising:
a processor configured to:
identify a frame pair to be encoded;
encode the frame pair, using a first bit rate, to form first encoded data; and
encode the frame pair, using a second bit rate that is lower than the first bit rate, to form second encoded data by:
identifying an object in the frame pair in negative parallax;
determining an amount of negative parallax reduction to perform on the object in negative parallax as a function of the second bit rate used to encode the frame pair;
performing the determined amount of negative parallax reduction on the object; and
encoding the frame pair using the second bit rate without performing parallax reduction on objects in positive parallax; and
memory coupled to the processor.
6. The image processing system of claim 5 , wherein the processor is further configured to:
identify a second object in negative parallax in the frame pair; and
determine a parallax difference between the object in the negative parallax in the frame pair and the second object in negative parallax in the frame pair.
7. The image processing system of claim 6 , wherein the amount of negative parallax reduction performed is also a function of the parallax difference.
8. The image processing system of claim 7 , wherein the processor is further configured to:
transmitting the second encoded data to a playback device.
9. The image processing system of claim 8 , wherein said processor is further configured to claim 5 , wherein the processor encodes the frame pair using the first bit rate by:
determining a second amount of negative parallax reduction to perform on the object in negative parallax as a function of the first bit rate, the second amount of negative parallax reduction being less than the amount of negative parallax reduction determined as a function of the second bit rate;
performing the second amount of negative parallax reduction on the object; and
encoding the frame pair using the first bit rate.
10. The image processing system of claim 9 , wherein said processor is further configured to:
encode the frame pair using a mono encoding method by:
selecting a single image from the frame pair; and
encoding the single image without parallax.
11. A non-transitory computer readable medium including processor executable instructions that, when executed by a processor, control an image processing system to:
identify a frame pair to be encoded;
encode the frame pair, using a first bit rate, to form first encoded data; and
encode the frame pair, using a second bit rate that is lower than the first bit rate, to form second encoded data by:
identifying an object in the frame pair in negative parallax;
determining an amount of negative parallax reduction to perform on the object in negative parallax as a function of the second bit rate used to encode the frame pair;
performing the determined amount of negative parallax reduction on the object; and
encode the frame pair using the second bit rate without performing parallax reduction on objects in positive parallax.
12. A method of encoding stereoscopic image data, the method comprising:
identifying a frame pair to be encoded;
selecting an encoding mode that includes negative parallax reduction;
identifying an object in the frame pair in negative parallax;
determining an amount of negative parallax reduction to perform on the object in negative parallax as a function of the bit rate being used to encode the frame pair;
performing the determined amount of negative parallax reduction on the object; and
encoding the frame pair using the bit rate without performing parallax reduction on objects in positive parallax.
13. The method of claim 12 , wherein determining an amount of parallax reduction includes determining a parallax reduction offset.
14. The method of claim 12 , wherein the selected encoding mode includes encoding the frame pair using multiple different bit rates.
15. The method of claim 14 , wherein encoding the frame pair using multiple different bit rates includes:
applying a lower amount of negative parallax reduction on the frame pair when encoding the frame pair using a higher bit rate; and
applying a higher amount of negative parallax reduction on the frame pair when encoding the frame pair using a lower bit rate.
16. The method of claim 1 , wherein:
identifying an object in negative parallax in the frame pair comprises:
identifying a closest object in the frame pair; and
determining whether the closest object is over a predetermined size; and
determining an amount of negative parallax reduction to perform on the object comprises:
determining a parallax difference D of the identified closest object; and
determining the amount of negative parallax reduction to perform as a function of the second bit rate and the determined parallax difference D of the identified closest object.
17. The method of claim 16 , wherein the closest object is the object perceived to be closest relative to a viewer.
18. The method of claim 12 , wherein:
identifying an object in negative parallax in the frame pair comprises:
identifying a closest object in the frame pair;
determining whether closest object is over a predetermined size; and
determining an amount of negative parallax reduction to perform on the object comprises:
determining a parallax difference D of the identified closest object; and
determining the amount of negative parallax reduction to perform as a function of the second bit rate and the determined parallax difference D of the identified closest object.