Image processing apparatus, control method thereof, and non-transitory computer-readable storage medium
The present invention provides an image processing apparatus operable to process first and second image data from an image capturing unit capable of amplifying, with different gains, a signal obtained by photoelectric conversion and outputting the first and second image data, wherein the apparatus comprises an acquiring unit configured to acquire an exposure difference between the first and second image data; a correcting unit configured to determine a correction amount for reducing a noise difference between the first and second image data based on the exposure difference acquired by the acquiring unit and correct at least one of the first and second image data based on the determined correction amount; and a generating unit configured to generate a composite image by compositing the first and second image data, at least one of which has been corrected by the correcting unit.
1 . An image processing apparatus operable to process first image data and second image data obtained from an image capturing device that is capable of amplifying, with a first gain and a second gain being lower than the first gain, a signal obtained by photoelectric conversion to obtain the first image data and second image data, respectively, the apparatus comprising:
at least one memory configured to store instructions; and
at least one processor coupled to the at least one memory and configured to execute the instructions to:
(1) apply a gain to the second image data so that brightness of the second image data matches brightness of the first image data;
(2) apply a noise reduction process to the second image data of which the brightness has been corrected; and
(3) generate composite image data by compositing (a) the second image data having had applied thereto the noise reduction process and (b) the first image data.
2 . The apparatus according to claim 1 , wherein the at least one processor is further configured to execute the instructions to:
apply to the second image data, as the noise reduction process, a filter processing that averages a value of a pixel of interest with values of other pixels nearby the pixel of interest.
3 . The apparatus according to claim 1 , wherein the at least one processor is further configured to execute the instructions to:
(1) determine whether to apply the noise reduction process in accordance with an exposure difference between the first image data and the second image data, the exposure difference being based on exposure parameters or a control exposure used to obtain the signal; and
(2) only apply the noise reduction process to the second image data of which the brightness has been corrected in a case where it is determined that the noise reduction process is to be applied.
4 . The apparatus according to claim 3 , wherein the at least one processor is further configured to execute the instructions to acquire the exposure difference by referencing a predetermined table based on the exposure parameters,
wherein the amount of the gain applied to the second image data is determined based on the exposure difference.
5 . The apparatus according to claim 1 , wherein the at least one processor is further configured to execute the instructions to generate high dynamic range (HDR) image data.
6 . The apparatus according to claim 5 , wherein the the at least one processor is further configured to execute the instructions to generate information indicating a compositing ratio of each pixel in two image data used when generating the HDR image data.
7 . The apparatus according to claim 1 , wherein the image capturing device is included.
8 . A control method of an image processing apparatus operable to process first image data and second image data obtained from an image capturing unit capable of amplifying, with a first gain and a second gain being lower than the first gain, a signal obtained by photoelectric conversion to obtain the first image data and the second image data, respectively, the method comprising:
applying a gain to the second image data so that brightness of the second image data matches brightness of the first image data;
applying a noise reduction process to the second image data of which the brightness has been corrected; and
generating composite image data by compositing (a) the second image data having had applied thereto the noise reduction process and (b) the first image data.
9 . A non-transitory computer-readable storage medium storing instructions which, when read and executed by a computer, causes the computer to execute steps of a method of controlling an image processing apparatus operable to process first image data and second image data obtained from an image capturing unit capable of amplifying, with a first gain and a second gain being lower than the first gain, a signal obtained by photoelectric conversion to obtain the first image data and the second image data, respectively, the method comprising:
applying a gain to the second image data so that brightness of the second image data matches brightness of the first image data;
applying a noise reduction process to the second image data of which the brightness has been corrected; and
generating composite image data by compositing (a) the second image having had applied thereto the noise reduction process and (b) the first image data.