Method for infrared image correction and enhancement
View Patent ↗A method for correcting defects in one or more frames of motion picture film, the method includes the steps of generating an image that includes an infrared channel and one or more color channels; providing an infrared unbuilding model that includes at least one non-linear component that accounts for cross-talk between the one or more color channels and the infrared channel; providing one or more parameters for the infrared unbuilding model; and applying the infrared unbuilding model parameters to the infrared unbuilding model to remove cross-talk between the one or more color channels and the infrared channel to generate an independent infrared channel that is free or substantially free of color channel content.
1. A method for correcting defects in one or more frames of motion picture film, the method comprising the steps of:
(a) generating an image that includes an infrared channel and one or more color channels;
(b) providing an infrared unbuilding model that includes at least one linear term and at least one non-linear term that accounts for cross-talk between the one or more color channels and the infrared channel, wherein at least one of the non-linear terms includes a square of one of the color channels or the product of two of the color channels, the infrared unbuilding model having the form:
I ideal =I measured +L R ×R+L R2 ×R 2 +L RG ×R×G+L RB ×R×B+L G ×G+L G2 ×G 2 +L GB ×G×B+L B ×B+L B2 ×B 2
where R, G and B are measured values for the red, green and blue color channels, respectively, I measured is a measured value for the infrared channel, L R , L G , and L B are model parameters for the linear terms, and L R2 , L G2 , L B2 , L RG , L RB and L GB are model parameters for the non-linear terms, wherein at least one of the model parameters for the linear terms is non-zero and at least one of the model parameters for the non-linear terms is non-zero;
(c) providing one or more parameters for the infrared unbuilding model; and
(d) applying the infrared unbuilding model parameters to the infrared unbuilding model to remove cross-talk between the one or more color channels and the infrared channel to generate an independent infrared channel that is free or substantially free of color channel content.
2. The method as in claim 1 , wherein the step (c) further comprises analyzing the one or more color channels and the infrared channel to estimate the model parameters of the infrared unbuilding model.
3. The method as in claim 1 , wherein step (b) further comprises providing a lookup table as corresponding to the infrared unbuilding model.
4. The method as in claim 2 , wherein step (c) further comprises using regression to determine the parameters for the infrared unbuilding model.
5. The method as in claim 1 , wherein the step (c) further comprises using a predetermined set of parameters for the infrared unbuilding model for a particular film stock.
6. The method as in claim 1 , wherein step (c) further comprises:
(i) estimating the model parameters for the infrared unbuilding model from the one or more color channels and the infrared channel;
(ii) comparing the estimated model parameters to model parameters for a library of infrared unbuilding models corresponding to known film stocks; and
(iii) using at least one set of model parameters from the library of infrared unbuilding models as a set of final model parameters for the infrared unbuilding model.
7. The method as in claim 2 , wherein step (c) further comprises using an iterative estimation process to determine the model parameters in which at least one pixel from the one or more color channels is excluded in a subsequent iteration.