Producing an extended dynamic range digital image
A method of producing a digital image with extended dynamic range, includes capturing at least a first full resolution digital image of a scene; combining pixels of a first full resolution digital image to produce a lower resolution digital image identifying dark regions in a first full resolution digital image and replacing the dark regions in the full resolution image with corresponding regions from the brighter, lower resolution image to thereby provide a digital image with extended dynamic range.
1. A method of producing a digital image with extended dynamic range, comprising by using a digital image processor the steps of:
a. capturing at least a first digital image of a scene having pixels with associated pixel values;
b. copying the first digital image to provide a second digital image;
c. assigning the pixels in the second digital image to sub-arrays;
d. combining the pixel values within each sub-array of the second digital image and replacing the pixel values of the second digital image so that the second digital image has higher pixel values with less noise and lower resolution than the first digital image; and
e. combining corresponding pixel values of the first digital image and the second digital image to produce a third digital image, including:
i. using the pixel values in the second digital image when corresponding pixel values in the first digital image are less than 50% of the maximum pixel value; and
ii. using the pixel values in the first digital image when corresponding pixel values in the first digital image are greater than 50% of the maximum code value whereby the third digital image has extended dynamic range.
2. The method of claim 1 wherein the first digital image is captured and stored in memory and the second digital image is produced from the stored first resolution digital image.
3. The method according to claim 1 wherein the combining step includes the function:
d ( x,y )=(1 −e wi(x,y) ) i ( x,y )+( e wi(x,y) ) c ( x,y )
wherein: d(x,y) is the pixel value for the third digital image; w is a negative number; i(x,y) is a pixel value from the first digital image; c(x,y) is a pixel value from the second digital image and x,y is the pixel location in the corresponding image.
4. A method of producing a digital image with extended dynamic range, comprising by using a digital image processor the steps of:
a. capturing at least a first digital image of a scene having pixels with associated pixel values;
b. capturing at least a second digital image of a scene having combined pixels and higher associated pixel values with less noise than corresponding pixels in the first digital image; and
c. combining corresponding pixel values of the first digital image and the second digital image to produce a third digital image, including:
i. using the pixel values in the second digital image when the corresponding pixel values in the first digital image are less than 50% of the maximum code value; and
ii. using the pixel values in the first digital image when corresponding pixel values in the first digital image are greater then 50% of the the maximum pixel value so that the third digital image has extended dynamic range.
5. The method of claim 4 wherein the pixel values are combined by binning the charge from two or more same colored pixels, by combining the voltages produced by the two or more same colored pixels, or by first converting the same colored pixel values to digital numbers and then combining the two or more pixel value, or combinations thereof.
6. The method of claim 5 wherein the voltages are combined by first charging capacitors of same colored pixels to the voltages produced by the same colored pixels and then connecting the capacitors together to combine the voltages.