Imaging device including high sensitivity pixels and low sensitivity pixel
An imaging device includes an image sensing device and an image signal processor. The imaging sensing device includes a pixel array of sensing pixels comprising a first pixel for sensing incident light and having a first dynamic range and a second pixel for sensing incident light and having a second dynamic range, the pixel array of sensing pixels structured to have a ratio of a number of the first pixels to all sensing pixels to be higher than a ratio of a number of second pixels to all sensing pixels. The image signal processor is configured to receive and process pixel data from the image sensing device to generate a high dynamic range (HDR) image corresponding to a larger dynamic range than the first dynamic range or the second dynamic range, based on pixel data of the first pixels and pixel data of the second pixels in the pixel array.
1 . An imaging device comprising:
an image sensing device including a pixel array of sensing pixels comprising at least one first pixel for sensing incident light and having a first dynamic range represented by a first measurable high light intensity without saturating the at least one first pixel and a first measurable low light intensity relative to a pixel noise level of the at least one first pixel and at least one second pixel for sensing incident light and having a second dynamic range represented by a second measurable high light intensity without saturating the at least one second pixel that is higher than the first measurable high light intensity of the at least one first pixel and a second measurable low light intensity relative to a pixel noise level of the at least one second pixel, wherein the pixel array of sensing pixels is structured to have a ratio of a number of the at least one first pixel to all sensing pixels to be higher than a ratio of a number of at least one second pixel to all sensing pixels; and
an image signal processor configured to receive and process pixel data from the image sensing device to generate a high dynamic range (HDR) image corresponding to a larger dynamic range than the first dynamic range or the second dynamic range, based on pixel data of the at least one first pixel and pixel data of the at least one second pixel in the pixel array,
wherein the at least one first pixel and the at least one second pixel are configured to sense a scene at a same time point.
2 . The imaging device according to claim 1 , wherein:
each of the at least one second pixel includes a red color filter corresponding to a red color, a blue color filter corresponding to a blue color, and a green color filter corresponding to a green color.
3 . The imaging device according to claim 2 , wherein:
the at least one second pixel including the green color filter has a lower sensitivity than the at least one second pixel including the red color filter or the at least one second pixel including the blue color filter.
4 . The imaging device according to claim 1 , wherein each of the at least one second pixel includes:
a photoelectric conversion element configured to generate photocharges corresponding to an intensity of incident light;
a logarithmic transistor having a gate and a drain that are coupled to a power-supply voltage and a source directly coupled to the photoelectric conversion element; and
a drive transistor configured to generate a voltage signal corresponding to a current flowing into the logarithmic transistor.
5 . The imaging device according to claim 1 , wherein:
the image signal processor is further configured to generate the HDR image by applying a gain corresponding to a difference in sensitivity between the first pixel and the second pixel to the pixel data of the at least one second pixel.
6 . The imaging device according to claim 1 , wherein:
the at least one first pixel and the at least one second pixel are configured to construct a shared pixel sharing a single floating diffusion region; and
in a binning mode in which the shared pixel generates a pixel signal corresponding to photocharges generated in the at least one first pixel and the at least one second pixel, the image signal processor is further configured to apply a gain corresponding to a difference in sensitivity between the first pixel and the second pixel to a resultant value obtained when pixel data corresponding to illuminance where the at least one first pixel is saturated is subtracted from pixel data of the shared pixel, thereby generating the HDR image.
7 . The imaging device according to claim 1 , wherein:
the at least one second pixel includes a light blocking structure that blocks at least a portion of incident light; and
the at least one first pixel is configured without including the light blocking structure.
8 . The imaging device according to claim 1 , wherein:
each of the at least one first pixel and the at least one second pixel includes an optical filter that selectively transmits light corresponding to a transmission wavelength band,
wherein the optical filter included in the at least one second pixel has a lower light transmittance than the optical filter included in the at least one first pixel.
9 . An imaging device comprising:
an image sensing device including a pixel array of sensing pixels comprising at least one first pixel for sensing incident light and having a first dynamic range represented by a first measurable high light intensity without saturating the at least one first pixel and a first measurable low light intensity relative to a pixel noise level of the at least one first pixel and at least one second pixel for sensing incident light and having a second dynamic range represented by a second measurable high light intensity without saturating the at least one second pixel that is higher than the first measurable high light intensity of the at least one first pixel and a second measurable low light intensity relative to a pixel noise level of the at least one second pixel, wherein the pixel array of sensing pixels is structured to have a ratio of a number of the at least one first pixel to all sensing pixels to be higher than a ratio of a number of the at least one second pixel to all sensing pixels; and
an image signal processor configured to receive and process pixel data from the image sensing device to generate a high dynamic range (HDR) image corresponding to a larger dynamic range than the first dynamic range or the second dynamic range, based on pixel data of the at least one first pixel and pixel data of the at least one second pixel in the pixel array, wherein:
the image signal processor is further configured to determine, for a frame including the pixel data of the at least one first pixel and the pixel data of the at least one second pixel, a high-brightness region in which a ratio of saturated first pixels per unit pixel group is higher than a predetermined ratio, and a low-brightness region in which a ratio of saturated first pixels per unit pixel group is equal to or less than a predetermined ratio; and
the image signal processor is further configured to generate the HDR image based on the pixel data of the at least one second pixel in the high-brightness region, and to generate the HDR image based on the pixel data of the at least one first pixel in the low-brightness region.
10 . The imaging device according to claim 9 , wherein:
the image signal processor is further configured to determine, in the low-brightness region, a first transition zone in which the ratio of saturated first pixels per unit pixel group is equal to or higher than a minimum ratio, the first transition zone having directivity in which brightness increases; and
the image signal processor is further configured to generate the HDR image by combining, in the first transition zone, the pixel data of the at least one first pixel and the pixel data of the at least one second pixel using a first composite weight.
11 . The imaging device according to claim 9 , wherein:
the image signal processor is further configured to determine the low-brightness region adjacent to a boundary between the low-brightness region and the high-brightness region to be a second transition zone; and
the image signal processor is further configured to generate the HDR image by combining, in the second transition zone, the pixel data of the at least one first pixel and the pixel data of the at least one second pixel using a second composite weight.
12 . The imaging device according to claim 11 , wherein:
the second composite weight decreases in the second transition zone as approaching the boundary between the low-brightness region and the high-brightness region.
13 . The imaging device according to claim 11 , wherein:
the second transition zone has a predetermined width,
wherein the predetermined width is determined by an average value of pixel data of first pixels adjacent to the high-brightness region.
14 . The imaging device according to claim 11 , wherein:
the image signal processor is further configured to determine the second transition zone to be in the low-brightness region adjacent to the boundary between the low-brightness region and the high-brightness region, the second transition zone being a specific region in which an average value of the pixel data of the first pixels adjacent to the high-brightness region is higher than a predetermined threshold.
15 . An imaging device comprising:
an image sensing device including at least one first pixel and at least one second pixel having a lower sensitivity than the at least one first pixel; and
an image signal processor configured to generate a high dynamic range (HDR) image corresponding to a dynamic range that is greater than a dynamic range of the at least one first pixel or a dynamic range of the at least one second pixel, based on pixel data of the at least one first pixel and pixel data of the at least one second pixel,
wherein
a ratio of the at least one first pixel to all pixels included in the image sensing device is higher than a ratio of the at least one second pixel to all pixels included in the image sensing device.
16 . The imaging device according to claim 15 , wherein the at least one first pixel includes a photoelectric conversion element to which light with an intensity that increases in response to an increase of an intensity of incident light is transferred, the intensity increasing at a rate higher as compared to that of the at least one second pixel.
17 . The imaging device according to claim 15 , wherein the image signal processor is further configured to generate the HDR image by adjusting one or more weights given to the pixel data of the at least one first pixel and the pixel data of the at least one second pixel.
18 . The imaging device according to claim 17 , wherein the image signal processor is further configured to adjust the one or more weights for one or more transition zones that are determined as various portions of a frame based on brightness levels.
19 . The imaging device according to claim 15 , wherein the at least one second pixel includes a light blocking structure that blocks at least a portion of incident light and is disposed over a substrate.
20 . The imaging device according to claim 15 , wherein each of the at least one first pixel and the at least one second pixel includes an optical filter that selectively transmits light corresponding to a transmission wavelength band, and wherein the optical filter included in the at least one second pixel has a lower light transmittance than the optical filter included in the at least one first pixel.