Local tone mapping circuit, image sensing device and operation method of the same

An image sensing device, comprising:

• an image sensor including a pixel array having a plurality of pixels;
• an image signal processor suitable for processing an output signal of the image sensor;
• and
• a local tone mapping circuit including:
• an average value calculation circuit suitable for calculating an average value of absolute values of differences between center pixel data and neighboring pixel data of the center pixel data, among pixel data outputted from the pixel array;
• a range calculation circuit suitable for calculating a range between a maximum value and a minimum value of the absolute values;
• and
• a local tone mapping strength adjusting circuit suitable for allocating a weighted value to the pixel data according to a distance between a center pixel and an edge pixel among neighboring pixels of the center pixel based on the range and the average value, and adjusting a local tone mapping strength according to an allocated weighted value.

An operation method of an image sensing device, comprising:

• calculating an average value of absolute values of differences between center pixel data and neighboring pixel data of the center pixel data among pixel data outputted from a pixel array including a plurality of pixels;
• calculating a range between a maximum value and a minimum value of the absolute values;
• allocating a weighted value to pixel data according to a distance between a center pixel and an edge pixel among neighboring pixels of the center pixel based on the range and the average value;
• and
• adjusting a local tone mapping strength according to an allocated weighted value.

An image sensing device comprising:

• an image sensor including a pixel array having a plurality of pixels;
• and
• a local tone mapping circuit suitable for:
• receiving pixel data from the pixel array, the pixel data including a plurality of pixel elements in a set kernel;
• calculating absolute values of differences between a center pixel item and each of neighboring pixel items adjacent to the center pixel item, among the plurality of pixel elements;
• allocating a weighted value for the center pixel item, based on a range between a maximum value and a minimum value of the absolute values and an average value of the absolute values;
• and
• adjusting a local tone mapping strength for the center pixel item according to the weighted value.