Legibility enhancement for a logo, text or other region of interest in video
View Patent ↗A video processing system enhances quality of an overlay image, such as a logo, text, game scores, or other areas forming a region of interest (ROI) in a video stream. The system separately enhances the video quality of the ROI, particularly when screen size is reduced. The data enhancement can be accomplished at decoding with metadata provided with the video data for decoding so that the ROI that can be separately enhanced from the video. In improve legibility, the ROI enhancer can increase contrast, brightness, hue, saturation, and bit density of the ROI. The ROI enhancer can operate down to a pixel-by-pixel level. The ROI enhancer may use stored reference picture templates to enhance a current ROI based on a comparison. When the ROI includes text, a minimum reduction size for the ROI relative to the remaining video can be identified so that the ROI is not reduced below human perceptibility.
1. A method for video signal processing comprising:
identifying an overlay region of interest (ROI) in a frame of a video signal;
identify at least one of contrast, brightness, hue, saturation and pixel density as a quality improvement factor for increasing quality of the ROI relative to a remaining portion of the frame of the video signal; and
providing the quality improvement factor as metadata with the frame to a decoder to enable processing of the video signal containing the frame using the metadata,
wherein identifying an overlay region comprises:
defining, by the electronic device, first and second areas within an image of the frame of the video signal;
calculating, by the electronic device, an alpha-blended value of a mean color value of the second area with an overlay color value; and
if a mean color value of the first area is closer to the alpha-blended value than it is to the mean color value of the second area, then defining the overlay area comprising at least one pixel within the first area to be within the ROI,
wherein calculating an alpha-blended value comprises applying an a priori alpha value and an a priori overlay color value, and
wherein the step of calculating an alpha-blended value is performed according to the formula {circumflex over (P)}(i,j)=(1−α){circumflex over (P)} b (i,j)+αP l (i,j),
wherein: {circumflex over (P)}(i,j) represents the calculated alpha-blended value
{circumflex over (P)} b (i,j) represents the mean image color value of the second area,
P l (i,j) represents the a-priori overlay color value, and
α represents the a-priori alpha value, and
wherein the step of identifying an overlay area is determined according to the formula C p =If (|{circumflex over (P)}(i,j)−P(i,j)|<|P(i,j)−{circumflex over (P)} b (i,j)|)
wherein: P(i,j) represents the mean color value of the first area,
{circumflex over (P)} b (i,j) represents the mean color value of the second area,
{circumflex over (P)}(i,j) represents the predicted mean color value of the first area, and
C p represents an overlay-blended graphic presence indicator.
2. The method of claim 1 , wherein the ROI is at least one of: a network logo, a sports score, and text.
3. The method of claim 1 , wherein the ROI is identified on a pixel-by-pixel basis.
4. The method of claim 1 , further comprising comparing the ROI to a stored overlay mask for the ROI using the decoder to enable better matching of the ROI to the stored overlay mask.
5. A method for video signal processing comprising:
identifying an overlay region of interest (ROI) in a frame of a video signal;
identify at least one of contrast, brightness, hue, saturation and pixel density as a quality improvement factor for increasing quality of the ROI relative to a remaining portion of the frame of the video signal; and
providing the quality improvement factor as metadata with the frame to a decoder to enable processing of the video signal containing the frame using the metadata,
wherein identifying an overlay region comprises:
defining, by the electronic device, first and second areas within an image of the frame of the video signal;
calculating, by the electronic device, an alpha-blended value of a mean color value of the second area with an overlay color value; and
if a mean color value of the first area is closer to the alpha-blended value than it is to the mean color value of the second area, then defining the overlay area comprising at least one pixel within the first area to be within the ROI, and
converting the ROI to black and white using the decoder when the alpha blended value is below a predetermined value.