Method and apparatus for converting a video image format to a group III fax format
First Claim
1. A video-to-Group III FAX converter, comprising:
- an video input for receiving a video input signal having sequential lines of video information;
a first conversion device for converting said lines of video information to an array of analog pixels in a frame buffer, each of said analog pixels having a digital value that represents an analog sampled value within an associated one of said lines of video information;
a mapping device for mapping said array of said analog pixels in said frame buffer to a binary image space associated with a Group III FAX format as binary image pixels, said binary image space comprising a larger number of binary image pixels than said analog pixels stored in said frame buffer, and wherein said mapping device is operable to expand each of said analog pixels stored in said frame buffer to provide an expanded array of analog pixels having an aspect ratio corresponding to the aspect ratio of said binary image pixels, said mapping device mapping said analog pixels in said frame buffer to said expanded array of analog pixels by mapping said analog pixels to virtual pixels in a virtual frame buffer as intermediate values and having an associated virtual image space substantially similar to the image space of said expanded array of analog pixels such that less than the total number of said virtual pixels corresponding to said binary image pixels are generated and stored at a given time in said virtual frame buffer, said mapping device having a spatial filter for filtering said intermediate mapped pixels in said virtual frame buffer to provide filtered virtual pixels which form said expanded array of analog pixels, said mapping device operable to map said expanded array of analog pixels to said binary image space; and
a FAX transmission device for transmitting said binary image pixels in said binary image space via a Group III FAX protocol over a FAX transmission medium.
1 Assignment
0 Petitions
Accused Products
Abstract
A video-to-FAX conversion system includes a video camera (10) for generating video signals which are then captured by a frame grabber and stored in a frame buffer (14). The data in the frame buffer is comprised of digitized values from the video signal which are stored in pixels with a first aspect ratio. A conversion device (16) is operable to map information in the frame buffer to the binary output space of a Group III FAX protocol and perform contrast enhancement thereon. The contrast enhancement includes the steps of first generating a histogram of all of the pixel values in the frame buffer (14) after expansion thereof into the output space of the Group III FAX. The histogram values are then utilized to generate an adjusted value for each of the gray scale values available for the pixels in the frame buffer 14. Each pixel in the frame buffer (14) is then expanded and the contrast enhancement applied thereto to adjust the values therein. The pixels are then processed through a dithering operation to diffuse error across the output space and then a determination is made as to whether it is a black pixel or a white pixel. This operation is done on-the-fly such that an expanded frame buffer is not required, as only a predetermined number of horizontal scan lines are required for both the contrast enhancement and image dithering operation prior to sending them to a Group III formatter (18) and, subsequently, to a Group III FAX transmitter (20) for the output of the Group III FAX.
-
Citations
18 Claims
-
1. A video-to-Group III FAX converter, comprising:
-
an video input for receiving a video input signal having sequential lines of video information; a first conversion device for converting said lines of video information to an array of analog pixels in a frame buffer, each of said analog pixels having a digital value that represents an analog sampled value within an associated one of said lines of video information; a mapping device for mapping said array of said analog pixels in said frame buffer to a binary image space associated with a Group III FAX format as binary image pixels, said binary image space comprising a larger number of binary image pixels than said analog pixels stored in said frame buffer, and wherein said mapping device is operable to expand each of said analog pixels stored in said frame buffer to provide an expanded array of analog pixels having an aspect ratio corresponding to the aspect ratio of said binary image pixels, said mapping device mapping said analog pixels in said frame buffer to said expanded array of analog pixels by mapping said analog pixels to virtual pixels in a virtual frame buffer as intermediate values and having an associated virtual image space substantially similar to the image space of said expanded array of analog pixels such that less than the total number of said virtual pixels corresponding to said binary image pixels are generated and stored at a given time in said virtual frame buffer, said mapping device having a spatial filter for filtering said intermediate mapped pixels in said virtual frame buffer to provide filtered virtual pixels which form said expanded array of analog pixels, said mapping device operable to map said expanded array of analog pixels to said binary image space; and a FAX transmission device for transmitting said binary image pixels in said binary image space via a Group III FAX protocol over a FAX transmission medium. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. A method for converting a video formatted signal into a Group III FAX formatted signal for transmission as a Group III FAX, comprising the steps of:
-
receiving a video input signal having sequential fines of video information; converting with a first conversion device the lines of video information to an array of analog pixels in a frame buffer, each of the analog pixels having a digital value that represents an analog sampled value within an associated one of the lines of video information, mapping the array of analog pixels in the frame buffer to a binary image space associated with a Group III FAX format as binary image pixels, the binary image space comprises a larger number of binary image pixels than the analog pixels stored in the frame buffer, and wherein the step of mapping is operable to expand each of the analog pixels stored in the frame buffer to provide an expanded array of analog pixels having an aspect ratio corresponding to the aspect ratio of the binary image the step of mapping the analog pixels in the frame buffer to the expanded array of analog pixels mapping the analog pixels to virtual pixels in a virtual frame buffer as intermediate values and having an associated virtual image space substantially similar to the image space of the expanded array of analog pixels such that less than the total number of the virtual pixels corresponding to the binary image pixels are generated and stored at a given time in the virtual frame buffer, the step of mapping filtering the intermediate mapped pixels in said virtual frame buffer with a spatial filter to provide filtered virtual pixels which form the expanded array of analog pixels, the step of mapping operable to map the expanded array of analog pixels to the binary image space; and transmitting the binary image pixels in the binary image space via a Group III FAX protocol over a FAX transmission medium. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
-
Specification