Image analysis – Color image processing
Reexamination Certificate
1995-10-27
2001-07-17
Mehta, Bhavesh (Department: 2621)
Image analysis
Color image processing
C382S260000, C382S218000, C358S518000
Reexamination Certificate
active
06263101
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to computerized picture reprocessing techniques and, more particularly, to the modification of colors of digitized picture stock by the application of mathematical models which are representative of photographic filters.
2. Description of Related Art
Film colorization, that is, colorizing black-and-white motion pictures, turned the film industry on its side in the mid-1980s. With less than adequate color selection and limited hardware and software capabilities, early attempts at colorizing notable black-and-white- film classics such as “Casablanca” and “The Big Sleep” produced less than favorable results, resulting in muddy hues that didn't always stick to the objects they were meant to color. Indeed, many film purists likened colorization to vandalism and defacement. However, in the 1990s a demand was created by the skyrocketing cost of producing new movies and television shows coupled with the burgeoning demand for movies and television shows to fill up time slots on the 500 or so cable channels, a demand which has been an incentive for colorizers to advance their craft to much higher levels of quality.
Colorizers have also applied their craft to more varied fields, fields which do not necessarily involve original black-and-white picture stock. For example, in the past if a director of a picture were unhappy with the color of a particular shot, the director would have had to reshoot the shot, which would have incurred high production costs. Further, commercial artists and advertisers may desire to intensify particular aspects of television commercials to be more appealing to consumers of target markets. Other special color effects may also be desired for a particular film, video, or television show, particularly music videos which are often intended for the less conservative teenage and young adult audience.
Other applications for the modification of digitized picture stock include the modification of the color of an entire digitized frame of the stock. For example, if a particular shot is shot during the day and the director later desires to have the shot be a night shot, then the entire shot would have to be reshot, incurring high costs. Furthermore, if a director of photography mistakenly used an improper filter or no filter at all for a particular shot, the shot would have to be completely redone with the desired filtered on the camera.
Accordingly, it is an object of the present invention to provide filtering techniques for modifying digitized picture stock.
SUMMARY OF THE INVENTION
Picture filtering technology of the present invention provides a method for modifying the color of digitized picture stock with mathematical filtering techniques. Generally speaking, picture filtering provides a method for modifying colors of a frame of picture stock by firstly digitizing the frame and storing the digitized frame in a computer. Two reference pictures are then selected from a picture or film library which are substantially identical, with one of the pictures having been shot with a filter and the other picture having been shot without a filter. The two reference pictures are digitized so that each set of resultant digital data or pixels corresponds to the set of pixels from the other reference picture. A quantitative differencing is then performed on a pixel-by-pixel basis, thereby determining the difference in, for example, the luminance value of each unfiltered pixels with each corresponding filtered pixel. In other words, for every variation of luminance value of the unfiltered picture there is then a corresponding quantitative difference value which, when multiplied with (or performed with some other arithmetic function) the unfiltered value, will yield the corresponding filtered value.
Accordingly, upon completing the quantitative differencing, a mathematical model is generated which is substantially a mathematical representation of the photographic filter used in the reference pictures. The mathematical model may be a function of any number of color variables, but in many applications, luminance values suffice for accurate filtering of images. The mathematical model is then applied to the digitized frame of the shot to be filtered by “feeding” the digital data through the mathematical model, thereby yielding “filtered” digital data. This process is analogous to light passing through a photographic filter, which light is filtered and recorded upon the exposed film. The filtered frame may then be viewed and further modified as desired. The change effected by the mathematical model may then be interpolated through other frames of the shot or applied to as many frames as desired.
One of the advantages of the filtering technology of the present invention is that if, for example, a director is unhappy with the overall color effect of a particular shot, rather than incur the great production cost of reshooting the shot, the shot may be digitized and “ran through” a mathematical model which is representative of a desired photographic filter, thereby filtering the frame or shot as desired. The shot may then be converted back to a desired form of picture stock.
In addition to other features, the filtering technology of the present invention has one feature which allows a user to propagate or interpolate any changes effected by the filter mathematical model through other frames of the shot, thereby saving the user much time and effort.
One of the features of the technology is that any reference pictures may be used, either from a film or picture library as mentioned or as developed by an individual director or colorist to meet a particular application, in order to generate the mathematical model which is representative of a desired filter.
Other aspects, advantages, and features of the picture filtering technology of the present invention will become apparent to those skilled in the art from a reading of the following detailed description with reference to the accompanying drawings.
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Cerulean Colorization LLC
Mehta Bhavesh
Oppenheimer Wolff & Donnelly LLP
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