Automatic film grain adjustment
View Patent ↗An inventive method obtaining film grains from a picture and processing the obtained film grains using a statistical distribution to determine new film grains. Preferably, a histogram of obtained film grain is subjected to the statistical distribution, which can be a normal distribution. Parameters of the normal distribution are controlled to determine the new film grains.
1. A method for automatically managing film grain for post production, comprising the steps of:
obtaining film grains from a picture by subtracting a grain-removed picture from a noise-reduced picture; and
controlling filtering of a statistical distribution of the obtained film grains to determine film grains different from the obtained film grains.
2. The method of claim 1 , wherein the step of controlling the filtering comprises setting filtering parameters to automatically obtain a desired grain pattern for any picture frame of a film.
3. The method of claim 2 , wherein the statistical distribution is a normal distribution of the noise representative of the obtained film grains.
4. The method of claim 1 , wherein the step of step of controlling the filtering comprises adjusting parameters for one of a 2×2 filter, noise sharpening filter and band pass filter to determine a wanted film grain pattern.
5. The method of claim 1 , wherein the step of controlling the filtering comprises finding a standard deviation with zero mean of the obtained film grains to determine film grains different from the obtained film grains.
6. The method of claim 1 , further comprising the step of adding the different film grains to the picture with the obtained film grains removed to generate a picture with a new film grain pattern.
7. The method of claim 2 , wherein the step of obtaining the film grains from a picture comprises reducing noise from a picture.
8. The method of claim 7 , wherein the step of obtaining film grains from a picture comprises removing film grain from the noise reduced picture.
9. The method of claim 1 , wherein the different film grains have grain patterns and grain levels different from the obtained film grains.
10. An apparatus for automatically managing film grain for post production, comprising:
means for obtaining film grains from a picture by subtracting a grain-removed picture from a noise-reduced picture; and
means for controlling parameters of a filter for filtering of a statistical distribution of the obtained film grains to determine film grains different from the obtained film grains.
11. The apparatus of claim 10 , wherein the means for controlling parameters of the filter for filtering the statistical distribution comprises setting means for setting filtering parameters to automatically obtain a desired grain pattern for any picture frame of a film.
12. The apparatus of claim 10 , wherein means for controlling parameters of the filter comprises means for adjusting parameters for one of a 2×2 filter, noise sharpening filter and band pass filter to determine film grains with one of grain patterns and grain levels.
13. The apparatus of claim 10 , wherein the statistical distribution comprises a normal distribution of the obtained film grains.
14. The apparatus of claim 10 , wherein the filter for filtering the statistical distribution finds a standard deviation with zero mean of the obtained film grains to determine film grains different from the obtained film grains.
15. The apparatus of claim 10 , further comprising means for adding the different film grains to the picture with the obtained film grains removed to generate a picture with new film grains.
16. The apparatus of claim 10 , wherein the means for obtaining film grains from a picture comprises means for reducing noise from a picture.
17. The apparatus of claim 16 , wherein the means for obtaining film grains from a picture comprises means for removing film grain from the noise reduced picture.
18. The apparatus of claim 10 , wherein the different film grains have a grain pattern and grain level different from that of the obtained film grain.