Image sensor, image signal processor, and operating method of image signal processor
A method of operating an image signal processor includes storing, by a color shading profile storage circuit, region-specific color shading values extracted from first image data, obtaining, by a region of interest-obtaining circuit, a region of interest, receiving, by a global white balance gain-receiving circuit, a global white balance gain from an application processor, calculating, by a region-specific white balance gain-calculating circuit, region-specific color shading weights, based on a first color shading value of the region of interest and a second color shading value for each region, calculating, by the region-specific white balance gain-calculating circuit, region-specific white balance gains, based on the global white balance gain and the region-specific color shading weights, and correcting, by a white balance-correcting circuit, white balance of second image data, based on the region-specific white balance gains.
1 . A method of operating an image signal processor, the method comprising:
storing region-specific color shading values extracted from first image data associated with an image;
obtaining information identifying a region of interest of the image;
receiving a global white balance gain;
calculating region-specific color shading weights based on a first color shading value of the region of interest and a second color shading value for each region of the image;
calculating region-specific white balance gains based on the global white balance gain and the region-specific color shading weights; and
correcting white balance of second image data associated with the image based on the region-specific white balance gains.
2 . The method of claim 1 , wherein the obtaining of the region of interest and the receiving of the global white balance gain are performed on a first image frame of the second image data, and
the calculating of the region-specific white balance gains and the correcting of the white balance are performed on a second image frame, which is a next frame of the first image frame.
3 . The method of claim 1 , wherein the receiving of the global white balance gain comprises receiving the global white balance gain from an application processor, and wherein the obtaining of the region of interest comprises receiving the region of interest from the application processor.
4 . The method of claim 1 , wherein the obtaining of the region of interest comprises:
calculating, from the second image data, region-specific sum of absolute difference (SAD) values for phase difference detection; and
extracting, as the region of interest, a region with a minimum SAD value among the region-specific SAD values.
5 . The method of claim 1 , wherein the obtaining of the region of interest comprises:
calculating an average value of the region-specific color shading values; and
extracting, as the region of interest, a virtual region with the average value.
6 . The method of claim 1 , wherein the calculating of the region-specific white balance gains comprises calculating, as the region-specific color shading weights, a ratio of the second color shading value to the first color shading value.
7 . The method of claim 1 , wherein the calculating of the region-specific white balance gains comprises calculating the region-specific white balance gains by multiplying the global white balance gain by the region-specific color shading weights.
8 . The method of claim 1 , wherein the region-specific color shading values represent amounts of light of a red wavelength, a green wavelength, and a blue wavelength for each region.
9 . The method of claim 1 , wherein the obtaining of the region of interest comprises obtaining coordinate values of at least one pixel in the region of interest.
10 . An image signal processor comprising:
a color shading profile storage circuit configured to store region-specific color shading values extracted from first image data associated with an image;
a region of interest-obtaining circuit configured to obtain information identifying a region of interest of the image;
a global white balance gain-receiving circuit configured to receive a global white balance gain from an application processor;
a region-specific white balance gain-calculating circuit configured to calculate region-specific color shading weights based on a first color shading value of the region of interest and a second color shading value for each region of the image, and configured to calculate region-specific white balance gains based on the global white balance gain and the region-specific color shading weights; and
a white balance-correcting circuit configured to correct white balance of second image data associated with an image based on the region-specific white balance gains.
11 . The image signal processor of claim 10 , wherein the region of interest-obtaining circuit and the global white balance gain-receiving circuit obtain the region of interest and receive the global white balance gain, respectively, for a first image frame of the second image data, and
the region-specific white balance gain-calculating circuit and the white balance-correcting circuit calculate the region-specific white balance gains and correct the white balance, respectively, for a second image frame, which is a next frame of the first image frame.
12 . The image signal processor of claim 10 , wherein the region of interest-obtaining circuit is configured to receive the region of interest from the application processor, extract, from the second image data, as the region of interest, a region with a minimum sum of absolute difference (SAD) value among region-specific SAD values calculated for phase difference detection, or extract, as the region of interest, a virtual region with an average value of the region-specific color shading values.
13 . The image signal processor of claim 10 , wherein the region-specific white balance gain-calculating circuit is configured to calculate, as the region-specific color shading weights, a ratio of the second color shading value to the first color shading value and calculate the specific white balance gains by multiplying the global white balance gain by the region-specific color shading weights.
14 . The image signal processor of claim 10 , wherein the region-specific color shading values represent amounts of light of a red wavelength, a green wavelength, and a blue wavelength for each region.
15 . An image sensor comprising:
a memory configured to store region-specific color shading values extracted from first image data generated at a first point in time; and
an image signal processor configured to obtain a region of interest for second image data generated at a second point in time after the first point in time, receive a global white balance gain from an application processor, extract a first color shading value of the region of interest from the region-specific color shading values stored in the memory, calculate region-specific color shading weights, based on the first color shading value and the region-specific color shading values, calculate region-specific white balance gains, based on the global white balance gain and the region-specific color shading weights, and correct white balance of the second image data, based on the region-specific white balance gains.
16 . The image sensor of claim 15 , wherein the image signal processor is configured to:
obtain the region of interest and receive the global white balance gain, for a first image frame of the second image data; and
extract the first color shading value, calculate the region-specific color shading weights, calculate the region-specific white balance gains, and correct the white balance, for a second image frame, which is a next frame of the first image frame of the second image data.
17 . The image sensor of claim 15 , wherein the image signal processor is configured to receive the region of interest from the application processor, extract, from the second image data, as the region of interest, a region with a minimum sum of absolute difference (SAD) value among region-specific SAD values calculated for phase difference detection, or extract, as the region of interest, a virtual region with an average value of the region-specific color shading values.
18 . The image sensor of claim 15 , wherein the image signal processor is configured to calculate, as the region-specific color shading weights, a ratio of the second color shading value to the first color shading value and calculate the region-specific white balance gains by multiplying the global white balance gain by the region-specific color shading weights.
19 . The image sensor of claim 15 , wherein the region of interest represents coordinate values of one pixel.
20 . The image sensor of claim 19 , wherein, when the region of interest comprises a plurality of pixels, the region of interest represents coordinate values of one pixel located at a center among the plurality of pixels.