WO2011071469A1

WO2011071469A1 - Phosphor decay based progressive content

Info

Publication number: WO2011071469A1
Application number: PCT/US2009/006456
Authority: WO
Inventors: Ronald Douglas Johnson
Original assignee: Thomson Licensing SAS
Current assignee: Thomson Licensing SAS
Priority date: 2009-12-09
Filing date: 2009-12-09
Publication date: 2011-06-16
Anticipated expiration: 2012-06-09
Also published as: TW201143419A

Abstract

A video processor processes interlaced content for progressive display by decreasing brightness independently to odd and even interlaced lines of the interlaced content on a frame by frame basis. The processor decreases the brightness of the interlaced lines using phosphor decay dimming applied independently to the odd and even interlaced lines of the interlaced content. In one instance, the processor stores the odd and even interlaced lines in separate buffers where it applies the phosphor decay dimming on each buffer at different frames. The processor determines a dimming interval based on a multiple of a rate associated with the interlaced content. In one instance, the processor outputs progressive content at an approximately 120 Hertz rate and dims the odd and even interlaced lines on a four frame cycle. The processor can be associated with content authoring systems and/or content presentation devices and the like.

Description

PHOSPHOR DECAY BASED PROGRESSIVE CONTENT

TECHNICAL FIELD

The subject matter relates generally to video, and more particularly to systems and methods for simulating phosphor decay on progressive video output.

BACKGROUND

[0001] Tube based televisions used phosphor screens with beams that excited the phosphor to produce images. The beams worked by first drawing odd lines of the image and then drawing even lines of the image on the phosphor screen. The method of drawing odd and then even lines of the image became known as "interlacing." Television standards promoted this type of video because the technology at the time supported it. As technology progressed, displays were developed that allowed both odd and even lines to be drawn simultaneously. This made the necessity of interlaced video obsolete. However, many video sources still utilized the interlacing standards, so "de-interlacers" were developed to convert the interlaced video to non-interlaced video or "progressive" video. The conversion is not without its problems though, and, often, the resulting progressive video is blurry or has artifacts from the conversion process.

SUMMARY

[0002] Interlaced content is converted to progressive content by reducing the brightness of odd and even lines of the interlaced content in an independent fashion. The brightness reduction is applied on a frame by frame basis to each set of odd and even lines independently and starting on different frames. The output progressive frame rate is a multiple of the interlaced content frame rate to allow a progression of diminishing brightness levels for each input frame of the interlaced content. This mimics how a phosphor based screen would show the interlaced content, allowing the eye to see a much smoother transition of frames. This allows progressive display of the interlaced content while maintaining the quality of the original and without the artifacts found in typical de-interlacing video processors. In one instance, the brightness levels of odd and even lines of the interlaced content are adjusted according to phosphor decay curves. This most closely allows the progressive video to mimic the original interlaced content shown on a phosphor based tube display. The processing can be done in "real-time" on interlaced content for viewing and/or pre- authored on a medium such as a DVD and the like for future viewing.

[0003] The above presents a simplified summary of the subject matter in order to provide a basic understanding of some aspects of subject matter embodiments. This summary is not an extensive overview of the subject matter. It is not intended to identify key/critical elements of the embodiments or to delineate the scope of the subject matter. Its sole purpose is to present some concepts of the subject matter in a simplified form as a prelude to the more detailed description that is presented later.

[0004] To the accomplishment of the foregoing and related ends, certain illustrative aspects of embodiments are described herein in connection with the following description and the annexed drawings. These aspects are indicative, however, of but a few of the various ways in which the principles of the subject matter can be employed, and the subject matter is intended to include all such aspects and their equivalents. Other advantages and novel features of the subject matter can become apparent from the following detailed description when considered in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] FIG. 1 is a block diagram of a progressive video system in accordance with an aspect of an embodiment.

FIG. 2 is another block diagram of a progressive video system in accordance with an aspect of an embodiment.

FIG. 3 is an example of progressive video processing in accordance with an aspect of an embodiment.

FIG. 4 is a flow diagram of a method of processing video in accordance with an aspect of an embodiment.

FIG. 5 is another flow diagram of a method of processing video in accordance with an aspect of an embodiment. DETAILED DESCRIPTION

[0006] The subject matter is now described with reference to the drawings, wherein like reference numerals are used to refer to like elements throughout. In the following description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the subject matter. It can be evident, however, that subject matter embodiments can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to facilitate describing the embodiments.

[0007] As used in this application, the term "component" is intended to refer to hardware, software, or a combination of hardware and software in execution. For example, a component can be, but is not limited to being, a process running on a processor, a processor, an object, an executable, and/or a microchip and the like. By way of illustration, both an application running on a processor and the processor can be a component. One or more components can reside within a process and a component can be localized on one system and/or distributed between two or more systems. Functions of the various components shown in the figures can be provided through the use of dedicated hardware as well as hardware capable of executing software in association with appropriate software.

[0008] When provided by a processor, the functions can be provided by a single dedicated processor, by a single shared processor, or by a plurality of individual processors, some of which can be shared. Moreover, explicit use of the term "processor" or "controller" should not be construed to refer exclusively to hardware capable of executing software, and can implicitly include, without limitation, digital signal processor ("DSP") hardware, read-only memory ("ROM") for storing software, random access memory ("RAM"), and non-volatile storage. Moreover, all statements herein reciting instances and embodiments of the invention are intended to encompass both structural and functional equivalents. Additionally, it is intended that such equivalents include both currently known equivalents as well as equivalents developed in the future (i.e., any elements developed that perform the same function, regardless of structure).

[0009] FIG. 1 illustrates a system 100 that incorporates a progressive video processor 102 to interlaced video content 104 for displaying on a progressive display 106 and/or for storing on a progressive content medium 108. The interlaced video content 102 is video originated as content created for tube based displays and/or any display that requires the interlacing of the scan lines and the like. In general, the NTSC standard (National Television System Committee broadcasting standard), found in the United States, requires this type of video for broadcast on television networks. The progressive display 106 can include, but is not limited to, plasma displays, liquid crystal displays (LCD), light emitting diode (LED) displays, OLED displays, and other types of displays and the like. The progressive content medium can include, but is not limited to, progressive content stored on a DVD, VCD, thumb drive, hard drive and/or other media and the like. The progressive processor 102 can be associated with a media content manufacturing system (e.g., a DVD authoring system and the like), a set top box, a television, a display, a disc player (DVD and the like), handheld mobile electronic device and/or a disc recorder (DVD and the like) and the like. It 102 can reside within, on and/or near these systems. For example, the location between a progressive video processor 102 and a progressive display 106 can be local and/or remote (fragmented implementations can permit both local and remote portions of the progressive video processor 102). In another example, the progressive video processor 102 can be part of an authoring system such that the resulting progressive video is stored on media for subsequent viewing.

[0010] In FIG. 2, a system 200 uses a progressive video processor 202 to process interlaced video content 204 for displaying on a progressive display 206 and/or for storing on a progressive content medium 218. In one example, the progressive video processor 202 receives the interlaced video content 204 at 29.97 Hz (approx. 30 Hz) and displays output for the progressive display 206 and/or the progressive content medium 218 at four times the input frequency at 120 Hz

(approximate for 4 x 29.97 Hz). One can appreciate that other ratios can be used for the input to output rates. Although, for example, using a lower ratio of rates can yield less subjective quality, it can still be an improvement for smaller displays such as for handheld mobile electronics such as cell phones, PDA's and the like. Higher ratios allow for smoother brightness control by providing more frames to dim over the same time period. Thus, each frame brightness reduction would not be as dramatic as in a lower ratio where the brightness reduction steps would be of a greater percentage. [0011] In this example system 200, the progressive video processor 202 uses a line separator 208 to separate the interlaced video content 204 into odd and even line sets. The odd line sets are then stored in buffer 1 210 and the even line sets are then stored in buffer 2 212. A line dimmer 214 is then used to reduce or dim the brightness of the line sets in each buffer 210, 212 independently. For example, the line dimmer 214 can reduce the brightness of buffer 1 210 (odd lines) by 25 percent and buffer 2 212 (even lines) by 75 percent at a given time. After the next time interval (typically based on the refresh rate of an associated progressive display), the line dimmer 214 can reduce each buffer 210, 212 again by a different percentage and so forth.

[0012] A progressive output 216 determines a refresh rate for the progressive display and/or is pre-programmed at a specific refresh rate interval. A user input can also be used to input a specific input for the refresh rate that the progressive output 216 and/or the line dimmer 214 uses. Either component 214, 216 can pass the refresh rate to the other component 214, 216. The progressive output 216 then retrieves the contents of buffer 1 210 (odd lines) and buffer 2 212 (even lines) at intervals based on the refresh rate and outputs them for the progressive display 206. When the progressive output 216 retrieves the buffer contents, the odd and even line sets have already been dimmed by the line dimmer 214 for a given refresh rate interval. Thus, each time the progressive output 216 retrieves the buffer contents, the line sets have had their brightness levels affected. The brightness levels can range from 0 percent to 100 percent. It is also to be noted that a brightness level at, for example, 75 percent equates to a dimming level of 25 percent, etc. Likewise, dimming levels can range from 100 percent to 0 percent. The progressive output 216 can also output the buffer contents to a content authoring system and/or to a content storage medium for subsequent viewing as progressive content.

[0013] To produce high quality progressive video from interlaced content, a high refresh rate display (general a display with a refresh rate that is a multiple of the interlaced content which is typically 29.97 frames per second (fps) - 30 fps is utilized from here on in as an approximation of 29.97 fps) is used to simulate phosphor brightness decay to reproduce better quality interlaced picture playback. Interlaced content does not image well on modern video displays. This is because most modern video displays are natively progressive output. Interlaced video is run through many different de-interlacing algorithms to try and minimize the visual artifacts, but this leads to blurring of the output, especially with motion. The de-interlacing is typically performed by compositing a static full frame rate video based on some combination of the two interlaced fields. This causes visible artifacts that make watching interlaced and especially NTSC content on a modern display very objectionable.

[0014] The reason the picture looks bad is because interlaced content historically was displayed on phosphorous based tube displays. Tube displays worked by sweeping an electron beam across the front of the display. This excited phosphors that would glow. The glowing decays over time until the phosphors are excited again (or not) as the electron beam sweeps by again. This produces a flashing effect at the pixel level but the human eye's "persistence of vision" causes us to see a solid picture. For NTSC recorded content the odd lines are refreshed by the electron beam and on the next pass the even lines are refreshed. The beam always alternates between even and odd and in the time between the phosphor glow decays.

[0015] By using very fast displays, the phosphor decay can be simulated. The display needs to be split into even and odd lines. The display's refresh rate can be any multiple of 29.97 Hz (approximately 30 Hz) greater than 2X. For example, assume a display is refreshing at 4X the rate of 29.97 (approximately 120 Hz). The phosphor decay rate can be modeled differently for different phosphors and is logarithmic. For this example, approximately full output, approximately ¾ output, approximately ½ output and approximately ¼ output is utilized as a simplistic and easily calculated decay rate model. One skilled in the art can appreciate that the brightness adjustment levels can be smaller (e.g., 1/8 steps for a refresh rate 8X the input rate, etc.) or larger (e.g., ½ steps for a refresh rate 2X the input rate, etc.) depending on refresh rate and how many adjustment intervals are available. Each brightness adjustment also is not required to be equal to the previous adjustment increment.

[0016] For an example of a 4X refresh rate of a progressive display, on frame

# 1 of the progressive display, the display shows odd lines at approximately full brightness and even lines at approximately ½ brightness. On frame #2 of the progressive display, the display shows odd lines at approximately 3/4 brightness and even lines at approximately ¼ brightness. On frame #3 of the progressive display, the display shows odd lines at approximately 1/2 brightness and even lines at

approximately full brightness. On frame #4 of the progressive display, the display shows odd lines at approximately 1/4 brightness and even lines at approximately ¾ brightness. This cycle repeats continuously.

[0017] In the example 300 shown in FIG. 3, a ball 322 in an interlaced picture

324 is moved from left to right and then remains in place. Odd lines 302 are shown changing brightness levels as the ball 322 moves from frame to frame 306-320. Even lines 304 are shown changing brightness levels as the ball 322 moves from frame to frame 306-320. In this example 300, the odd lines 302 are full brightness (0 percent dimmed) on frame 1 306 and frame 5 3 14. While the even lines 304 are full brightness (0 percent dimmed) on frame 3 10 and frame 7 31 8. Brightness levels are adjusted for the odd and even lines in each frame 306-320 but at different independent levels in each frame. This allows the 'scanning' lines to fade away during motion to provide a much smoother image on the progressive display. Thus, the interlaced picture 324 is displayed on a fast progressive display the same way it would have been displayed if it had been displayed with actual phosphors. The end result is that interlaced video is displayed in a very natural way on a progressive video output recreating a visual output that very closely matches the original video the way it was created and intended to be displayed with a phosphor based display.

[0018] In view of the exemplary systems shown and described above, methodologies that can be implemented in accordance with the embodiments will be better appreciated with reference to the flow charts of FIGs. 4-5. While, for purposes of simplicity of explanation, the methodologies are shown and described as a series of blocks, it is to be understood and appreciated that the embodiments are not limited by the order of the blocks, as some blocks can, in accordance with an embodiment, occur in different orders and/or concurrently with other blocks from that shown and described herein. Moreover, not all illustrated blocks may be required to implement the methodologies in accordance with the embodiments.

[0019] In FIG. 4, a flow diagram of a method 400 of processing video content in accordance with an aspect of an embodiment is shown. The method starts 402 by determining a dimming interval based on a multiple of an interlaced content rate 404. The dimming interval can also be construed as a brightness reduction interval, etc. In essence, the brightness level is adjusted at approximately each interval. It is common for the interlaced content rate to be 29.97 fps. Thus the dimming interval could be based on 2X, 3X, 4X, 5X, etc. of the interlaced content rate. The refresh rate of a progressive display would need to be capable of handling whichever multiple is being used as the dimming interval. Phosphor decay based dimming is then applied to odd lines of the interlaced content for each dimming interval 406. The dimming or brightness level adjustment can be based on a phosphor decay curve. Other examples can be based on arbitrary brightness level adjustments or a set pattern of brightness level adjustments and the like. The more adjustment levels available (higher refresh rates), the more natural the interlaced content will appear on the progressive display. Phosphor decay based dimming is then applied to even lines of the interlaced content for each dimming interval at a different dimming level than that of the odd lines 408, ending the flow 410. The dimming, as mentioned above, can also be based on arbitrary and/or set patterns of brightness level adjustments. The brightness levels of the odd and even lines are adjusted independently of each other for each frame interval. In this example method 400, the odd lines are adjusted first in an arbitrary first frame. However, one skilled in the art can appreciate that the method works equally well by starting with the even lines in an arbitrary first frame as well and then altering the brightness levels of the odd lines, etc. The output of the method 400 can be viewed directly and/or stored on content media for subsequent viewing. Thus, the method 400 can be used in display processing devices such as set top boxes and the like and/or in content authoring systems such as those for creating DVD media and the like.

[0020] In FIG. 5, a flow diagram of a method 500 of processing video in accordance with an aspect of an embodiment is illustrated. The method starts 502 by obtaining interlaced content 504. The interlaced content is then separated into even and odd line sets 506. Each line set is then stored in a separate buffer 508. By providing separate buffers, brightness levels can be applied to odd and even lines independently. Other methods can be utilized to accomplish the same effect (e.g., an algorithm that identifies even and odd lines to apply brightness adjustments independently, etc.) Phosphor decay based dimming is then independently applied to each buffer 510. Typically, this means that the brightness level of the odd lines and the brightness level of the even lines differ at a given time interval. The line sets of each buffer are then output together at regular intervals 512, ending the flow 5 14. By buffering the odd and even lines and then applying the brightness level adjustments independently, a progressive output has brightness level adjustments ready for each frame of the output. The output of the method 500 can be viewed directly and/or stored on content media for subsequent viewing. Thus, the method 500 can be used in display processing devices such as set top boxes and the like and/or in content authoring systems such as those for creating DVD media and the like.

[0021] It is to be appreciated that the systems and/or methods of the embodiments can be utilized in video processing facilitating computer components and non-computer related components alike. Some video processing can be fully and/or partially implemented in software. Further, those skilled in the art will recognize that the systems and/or methods of the embodiments are employable in a vast array of electronic related technologies, including, but not limited to, set top boxes, displays, disc players/recorders, televisions and/or handheld electronic devices, and the like.

[0022] What has been described above includes examples of the

embodiments. It is, of course, not possible to describe every conceivable combination of components or methodologies for purposes of describing the embodiments, but one of ordinary skill in the art can recognize that many further combinations and permutations of the embodiments are possible. Accordingly, the subject matter is intended to embrace all such alterations, modifications and variations that fall within the spirit and scope of the appended claims. Furthermore, to the extent that the term "includes" is used in either the detailed description or the claims, such term is intended to be inclusive in a manner similar to the term "comprising" as "comprising" is interpreted when employed as a transitional word in a claim.

Claims

1 . A system, comprising:

a processor that processes interlaced content for progressive display by decreasing brightness independently to odd and even interlaced lines of the interlaced content on a frame by frame basis.

2. The system of claim 1 , wherein the processor decreases the brightness of interlaced lines using phosphor decay dimming applied independently to the odd and even interlaced lines of the interlaced content.

3. The system of claim 2, wherein the processor stores the odd and even interlaced lines in separate buffers.

4. The system of claim 3, wherein the processor applies the phosphor decay dimming on each buffer at different frames.

5. The system of claim 2, wherein the processor determines a dimming interval based on a multiple of a rate associated with the interlaced content.

6. The system of claim 2, wherein the processor outputs progressive content at an approximately 120 Hertz rate and dims the odd and even interlaced lines on a four frame cycle.

7. The system of claim 6, wherein the processor dims odd lines at approximately 0 percent and even lines at approximately 50 percent for the first frame, dims odd lines at approximately 25 percent and even lines at approximately 75 percent for the second frame, dims odd lines at approximately 50 percent and even lines at approximately 0 percent for the third frame, and dims odd lines at approximately 75 percent and even lines at approximately 25 percent for the fourth frame in a cycle. 1 I

8. The system of claim I , wherein the processor is associated with at least one of a content authoring system and a content presentation device.

9. A method, comprising:

decreasing brightness independently to odd and even interlaced lines of interlaced content on a frame by frame basis to produce progressive content.

10. The method of claim 9 further comprising the step of:

using phosphor decay dimming applied independently to the odd and even interlaced lines of the interlaced content to decrease brightness.

1 1. The method of claim 10 further comprising the steps of:

storing the odd and even interlaced lines in separate buffers; and

decreasing brightness by applying the phosphor decay dimming on each buffer at different frames.

12. The method of claim 10 further comprising the step of:

determining a dimming interval based on a multiple of a rate associated with the interlaced content.

13. The method of claim 10 further comprising the steps of:

dimming the odd and even interlaced lines on a four frame cycle; and outputting progressive content at an approximately 120 Hertz rate.

14. The method of claim 13 further comprising the steps of:

dimming odd lines at approximately 0 percent and even lines at approximately 50 percent for the first frame;

dimming odd lines at approximately 25 percent and even lines at

approximately 75 percent for the second frame;

dimming odd lines at approximately 50 percent and even lines at

approximately 0 percent for the third frame; and

dimming odd lines at approximately 75 percent and even lines at

approximately 25 percent for the fourth frame in a cycle.

15. A system, comprising:

means for decreasing brightness independently to odd and even interlaced lines of interlaced content on a frame by frame basis; and

means for outputting the odd and even interlaced lines as progressive content at a rate that is a multiple of the interlaced content rate.

16. The system of claim 15 further comprising:

means for decreasing the brightness using phosphor decay dimming.

17. A computer readable medium having stored thereon computer executable components of the system of claim 1 .