Exposure adjustment in an imaging apparatus
View Patent ↗An imaging apparatus for performing exposure adjustment based on the luminance of screen images through photoelectric conversion includes a structure for providing a signal to be applied to a screen for viewing images, a structure defining a region satisfying a predetermined condition based on where the luminance is excluded from a base region predetermined in the screen signal, and a structure for automatically providing exposure adjustment on the signal based on the luminance of a remaining region in the base region.
1. A method for providing exposure adjustment in an imaging apparatus, comprising:
a) capturing an image of a scene;
b) partitioning the image into a predetermined number of blocks of image data values;
c) determining, for each of the blocks of image data values, a difference between the image data value of the block and the image data value of a neighboring block to produce a plurality of difference values;
d) identifying those blocks having a difference value greater than a predetermined threshold value as contour blocks;
e) using the contour blocks to identify a subset of the predetermined number of blocks of image data values;
f) determining a ratio of the number of blocks of image data values in the subset to the predetermined number of blocks of image data values;
g) using the ratio as an input to a predetermined function to provide a weighting coefficient;
h) calculating an exposure value using all of the predetermined number of blocks of image data values;
i) using the image data values in the subset of the predetermined number of blocks to produce an exposure adjustment value;
j) using the weighting coefficient to modify the exposure adjustment value; and
k) using the modified exposure adjustment value to adjust the exposure value.
2. The method of claim 1 wherein image data values are luminance values.
3. The method of claim 1 further comprising:
l) using the adjusted exposure value to capture a subsequent image of the scene.
4. The method of claim 1 , wherein the predetermined function provides the same value weighting coefficient for all ratios that are greater than a threshold ratio value.
5. The method of claim 4 , wherein the predetermined function provides a weighting coefficient value which linearly varies for all ratios that are less than a threshold ratio value.